Review Article Saliva-Based Biosensors: Noninvasive Monitoring …downloads.hindawi.com/journals/bmri/2014/962903.pdf · 2019-07-31 · Review Article Saliva-Based Biosensors: Noninvasive

Review ArticleSaliva-Based Biosensors Noninvasive Monitoring Tool forClinical Diagnostics

Radha S P Malon1 Sahba Sadir2 Malarvili Balakrishnan1 and Emma P Coacutercoles1

1 Faculty of Biosciences and Medical Engineering (FBME) Universiti Teknologi Malaysia Building VO1 Block A Level 5Room 27 81310 Skudai Johor Malaysia

2 Faculty of Mechanical Engineering (FKM) Universiti Teknologi Malaysia 81310 Skudai Johor Malaysia

Correspondence should be addressed to Emma P Corcoles emmacorcolesgmailcom

Received 28 February 2014 Revised 16 July 2014 Accepted 11 August 2014 Published 8 September 2014

Academic Editor Michael Kalafatis

Copyright copy 2014 Radha S P Malon et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

Saliva is increasingly recognised as an attractive diagnostic fluid The presence of various disease signalling salivary biomarkersthat accurately reflect normal and disease states in humans and the sampling benefits compared to blood sampling are some of thereasons for this recognition This explains the burgeoning research field in assay developments and technological advancementsfor the detection of various salivary biomarkers to improve clinical diagnosis management and treatment This paper reviews thesignificance of salivary biomarkers for clinical diagnosis and therapeutic applications with focus on the technologies and biosensingplatforms that have been reported for screening these biomarkers

1 Introduction

Common clinical diagnosis is based on the determination ofblood biomarkers However this is an invasive proceduretoo aggressive for certain patients Saliva sampling is rela-tively simple and the presence of various disease-signallingbiomarkers in saliva has meant that it can accurately reflectnormal and disease states in humans Although saliva col-lection and determination present some disadvantages it hasbeen recognised as an attractive diagnostic fluid with anincreasing amount of assay developments and technologicaladvancements for the detection of various salivary biomark-ers

In humans oral fluid originatesmainly from three pairs ofmajor salivary glands (parotid sublingual and submandibu-lar) and a large number of minor salivary glands It alsocontains fluids from nonglandular origin such as oropharyn-geal mucosae crevicular fluid blood-derived compoundsand food debris [1 2] Typically the collection and evaluationof secretions from individual salivary glands are used forthe detection of gland-specific pathology such as infectionand obstruction However due to its easy sampling method

with or without stimulations whole saliva is more frequentlystudied especially for the evaluation of systemic disorders [3]

Generally saliva sampling involves a simple and non-invasive collection method that allows easy storage andtransport [2] This painless procedure is particularly usefulfor people with problems in collecting blood samples such ashaemophiliacs neonates elderly people and disabled peopleamong others [4] In addition it also increases the compli-ance of people who require frequent clinical monitoring withmultiple sampling over the day or several days thus increas-ing the feasibility for monitoring their health progressionand treatment outcomes [5] Unlike blood specimen salivasampling does not require specialised instruments or trainedpersonnel with phlebotomy skills it has minimal or no riskof crosscontamination among patients and offers very lowexposure of healthcare personnel to blood-borne pathogenssuch as HIV and hepatitis [5 6] However it is importantto standardise the method of collection in order to obtainsignificant results

To date a wide spectrum of compounds present in salivahas emerged as highly informative and discriminatoryThesebiomarkers might aid in (i) early detection and diagnosis of

Hindawi Publishing CorporationBioMed Research InternationalVolume 2014 Article ID 962903 20 pageshttpdxdoiorg1011552014962903

2 BioMed Research International

diseases (ii) supporting treatment decision making and (iii)monitoring disease progression andor treatment outcomesThese biomarkers have been previously studied by employingconventional collection and laboratory-based assay methodsAlthough saliva sampling using oral fluid collectors andcommercial devices is generally safe and convenient touse and provides sufficient homogeneous sample with lowviscosity it still presents several shortcomings such as (i)the requirement of supervision (ii) the need to follow theprocedures carefully to ensure sample adequacy and (iii)the relatively time-consuming process (sim1-2min) [7] On theother hand salivary analysis using laboratory-based assaymethods often requires relatively large volumes of sampleand involves multiple steps of sample acquisition labellingfreezing transportation processing in the laboratory (egcentrifugation sorting aliquoting and loading into theanalyser) analysis and finally results reporting It is atedious and lengthy process in which each step needs tobe performed carefully as it is fraught with several potentialquality failure points In such scenarios saliva sample storageprocedures between sampling and analysis also need to betaken into account as it may affect the relative stability ofthe salivary components In terms of financial implicationsthe analytical instruments utilised are expensive hence avail-able in centralised laboratories only There are also costsassociated with the testing supplies sample acquisition andtransport supplies as well as the labour costs incurred acrossthe total process The aforementioned drawbacks have led tothe demand for rapid and reliable quantification of salivarybiomarkers through the use of biosensing technology [8]Theability to immediately collect and analyse salivary biomarkerson site (point-of-care (POC)) provides countless advantagesfor clinical applications

Biosensors are small self-contained analytical devicesused for the detection and measurement of a particularsubstance (analyte) of interest A biological sensing element(eg enzymes antibodies nucleic acids etc) is placed inintimate contact with a transducer (eg optical electro-chemical piezoelectric etc) transforming the biorecognitionevent into a more simple and quantifiable signal Generallythe strength of the output signal is proportional to theconcentration of the analyte of interest Finally the resultis processed using associated electronics and embeddedsoftware systems which provide simple digital feedbackdisplayed using a reader device in a user-friendly mannerfor interpretation by nonexperts [5] However it is note-worthy that the reader device accounts for the most expen-sive part of the sensor so it is normally incorporated insensors that are intended for commercial purposes For acomprehensive description of the progress in biosensors formedical applications with specific emphasis in noninvasivemeasurement the following book chapter is recommended[9]

This paper reviews the significance of salivary biomarkersfor clinical diagnosis and therapeutic applications Eachbiomarker and its associated detection methods presentdifferent particularities drawbacks and challenges Hencethe most common salivary biomarkers and their biosensingmechanisms have been described separately focusing on

the reported technologies used for both the collection and thescreening of these biomarkers

2 Salivary Glucose

As glucose is a small organic molecule it has the abilityto move easily through the blood vessels membranes dif-fusing from the blood plasma to the gingival fluid via thegingival sulcus into saliva There are many controversialfindings regarding the correlation between capillary bloodglucose (CBG) and salivary glucose (SG) concentrationsin the literature In healthy subjects there is a lack ofrelationship between CBG and SG concentrations becauseinsulin from beta cells in the pancreas is released into thebloodstream to normalise the CBG level when the glucoseconcentration exceeds a certain limit [4 10] In diabetics SGconcentration is significantly higher than in healthy subjects[4 11ndash17] However the association between CBG and SGlevels among diabetics is ambiguously established as thereare contradicting studies that found both positive correlation[4 11 12 16] and absence of [14 17] correlation hencemakingthe use of SG concentration as an index for diabetes mellitusinconclusive

Gingival crevicular fluid (GCF) is an extracellular fluidsecreted from the epithelia of the gingival crevice a V shapedcrevice surrounding all teeth which is located between thetooth and the gingiva with a clinically normal depth of05 to 20mm [18 19] In the last decade researchers haveinvestigated the possibility of using gingival crevicular blood(GCB) as an assessmentmethod tomeasure glycaemia amongdiabetics The results revealed that there is a significantcorrelation between GCB glucose and CBG concentrations[20ndash28] During periodontal inflammation with or withoutthe complicating factor of diabetes an ample amount ofextravasated blood is produced [29] Since periodontal dis-ease is prevalent among diabetics the GCB collected with theprobing technique during a general periodontal examinationcan be used to diagnose diabetes or to monitor CBG levelin known diabetics This technique is inexpensive safe andeasy to performwithout the use of additional tools such as thesharp lancet for finger puncture Hence GCB concentrationis suitable for noninvasive CBG assessment especially inperiodontal management among diabetics [20ndash28]

The first glucose biosensor was developed by Clark andLyons [30] The biosensor consisted of an electrode thatmonitored the consumption of oxygen (O

2) catalysed by

glucose oxidase (GOx) enzyme as shown in

Glucose +O2

GOx997888997888997888rarr Gluconic acid

+Hydrogen peroxide (H2O2)

(1)

In order to determine SG concentration Yamaguchi et al[31] developed a system that combined flow injection anal-ysis and an O

2electrode The O

2consumed was detected

amperometrically and as the reaction progressed a decreasein the output current was observed due to the reduction inthe concentration of dissolved O

2that reached the sensor

(see (1)) A constant current proportional to the glucose

BioMed Research International 3

concentration in the sample solution was generated whenthe amount of O

2consumed on the enzyme membrane

was in equilibrium with the amount of O2released from

the sensor The system allowed monitoring the time-coursechanges of SG level in the range of 01 to 10mg dLminus1 using200120583L of sample solution The system was further improvedby replacing the O

2electrode with a hydrogen peroxide

(H2O2) electrode in the flow cell [32] In this glucose sensor

an increase in the concentration of H2O2was observed as

the reaction (see (1)) progressed resulting in an increase inthe output current A constant current proportional to theglucose concentration in the sample solution was generatedand detected using an amperometric circuitThe use of H

2O2

electrode type glucose sensor was more desirable than O2

electrode type glucose sensor because it reduced the influenceof dissolved O

2 The H

2O2-based saliva analysing system

required only 50 120583L of sample solution and it also enabled themonitoring of time-course changes of SG level in the range of01 to 10mg dLminus1

Another approach reported GOx enzyme immobilisedon a ferrocene modified gold (Au) film electrode usingglutaraldehyde (GA) for the crosslinking method [33] Fer-rocene derivatives are recognised as good electron shuttlesHence they are commonly used to eliminate O

2levels

dependence and electroactive biological species interferencewith the sensor signal The sensor reported working rangefor glucose measurement from 0 to 22mM with sensitivityof 2145 nA120583molminus1 cmminus2 and detection limit (DL) of 1 120583Mwithin a response time of 5 s In these studies saliva sampleswere collected using a conventional samplingmethod (dentalcotton rolls) and subsequently analysed using the previouslydiscussed SG sensors However in the following investiga-tions sampling devices were developed for integration withtheir respective sensors

Since GCB glucose concentration was also reportedsuitable for noninvasive CBG assessment [20ndash28] researchwas carried out towards the development of diagnosticdevices to collect and analyse GCF glucose level [19 34 35]The noninvasive GCF glucose monitoring system compriseda disposable GCF-collecting device glucose testing tape(GTT) and portable optical analyser [34 35] The workingprinciple of the device is illustrated in Figure 1 The GCFcollecting device was made of three sheets of laminatedpolyester film that led the sample solution automatically intothe built-in GTT integrated with chromogen (3 31015840 5 51015840-tetramethylbenzidine (TMBZ)) In the presence of glucoseH2O2was generated (see (1)) and this in turn oxidised

the TMBZ This reaction is catalysed by peroxidase (POx)enzyme resulting in a colour change on the GTT from whiteto bluish green

H2O2+ TMBZ

POx997888997888997888rarr Colour change (White 997888rarr Bluish green)

(2)

The colour intensity corresponding to the GCF glucose levelin the solution was then measured and the final outputwas displayed as CBG concentration on the GCF glucosemonitor The device was further modified to enable visual

confirmation of the sample collection and to reduce thesample volume size [19] When GCF sample was collectedusing the modified GCF collecting device (made of blackpolyester films) a colour change from white to black wasobserved hence confirming the completion of the GCFsampling process Besides that the volume of the sample wasfixed to be below 200 nL by reducing the tape size Comparedto previous methods which integrated the GCF collectingdevice with a GTT saturated with enzyme and chromogen[34 35] the new GCF collecting device was used to merelycollect the GCF sample alone whilst the analysis was carriedout separately by using combinedmicroplate fluorometer andluminometerThe reducedGCF sample collection time (fromabout 1-2min to 5ndash30 s only) and GCF sample evaporationas well as its increased accuracy repeatability sensitivity andspecificity are additional advantages of this device Hence ithas the potential to be used as a screening method for nonin-vasive CBGmeasurement among diabetics Furthermore theapplication of the reported method can be further extendedfor the collection and analysis of other biological fluidsproduced in small quantities for the diagnosis of variousother diseases [19]

Overall since the correlation between CBG and SGconcentrations still raises controversy it would be preferableto develop new biosensing technologies that focus on themeasurement of GCF glucose concentration A possible plat-form could be one that combines both sampling and analysisusing a cellulose fibre-based hand-held device For instancea type of dental floss that allows GCF sample collectionfollowed by immediate sample transcription to the devicevia capillary action and finally obtaining the GCF andorCBG glucose measurement instantaneously This simple andnoninvasive method could revolutionise the technology indiabetes care

3 Salivary Lactate

At low oxygen levels cells are forced to metabolise glucoseanaerobically leading to the production of lactic acid as aprimary by-product During elevated levels of lactic acid(hyperlactatemia) in blood a significant drop in the bloodpH occurs This physiological condition is known as lacticacidosis Hence it is important to monitor capillary bloodlactate (CBL) concentration especially among patients inintensive care units and operating rooms as lactic acidosis canlead to muscle damage that may result in heart attack [36] Itis also essential tomeasure CBL levels among diabetics due tothe close metabolic relationship between glucose and lactate[36 37] Besides that analysis of CBL concentration is of highinterest in sports medicine for athletes to tailor their trainingin order to optimise their performance [38 39] For instanceit is important to determine the anaerobic threshold (AT) ormaximum lactate steady state (MLSS) from the lactate loadcurves during exercise which is the maximum load whenlactate production is in equilibrium with lactate eliminationBased on the AT suitable exercise intensity can be preciselygiven to the athletes for different types of sports in order toproduce optimal results [38]


GCF collecting device

Glucose testing tape Holder


Laser head

Lens

Photodiode

GC

F gl

ucos

e (m

mol

L)

Calibration curve 1

Optical density (OD)

CB

G (m

mol

l)

Calibration curve 2

GCF glucose (mmolL)

Start

50mgdL

Glucose testing tape

GCF glucose monitor

Figure 1 The working principle of the GCF glucose monitor

Lactate can also be detected in saliva due to the passivediffusion of lactate from blood and secretion from salivaryglands [40]The typical lactate concentration in saliva rangesfrom 01 to 25mM [38] Since SL has a high correlationto CBL concentration typically a 1 4 salivablood ratio SLis suitable for noninvasive CBL analysis [41] especially forcritical-care patients diabetics and athletes [38 42]

Lactate biosensors follow the same principle as theirglucose counterparts since they also rely on oxidase enzymereaction for the biorecognition process In brief lactate isoxidised into pyruvate by lactate oxidase (LOx) enzymeconsuming O

2and producing H

2O2

Lactate +O2

LOx997888997888997888rarr Pyruvate +H

2O2

(3)

Several biosensors for SL measurements have been reportedOne of them is consisted of an electrochemical surface-type sensor that was incorporated with dual platinum (Pt)electrodes (one active lactate probe and the other inactive tolactate) and a common silversilver chloride (AgAgCl) ref-erence electrode developed on Plexiglas [4 42] The enzymemembrane was prepared by immobilising LOx enzyme usingcrosslinking method with GA After drying the enzymemembrane was cut into two pieces One piece was placedon one of the platinum electrodes (active lactate probe)

and the other one was immersed in boiling water for 1minbefore being placed on the other platinum electrode (inactiveto lactate) The use of dual platinum electrodes helped toevaluate and eliminate changes in background current dueto pH temperature and ionic strength variation as well ascurrent changes due to potential interferent substances Toimprove the permselectivity of the sensor cellulose acetateand polycarbonate membranes were used as the inner andouter blocking membranes respectivelyThe current changesdue to the production of H

2O2(see (3)) proportional to the

lactate concentration in the sample solutionweremeasured at065V versusAgAgCl using an electrochemical detectorThereported sensor required the measurement to be conductedin a bulk stirred solution that needed a relatively large volumeof sample and thus feasible in laboratory-based analysis onlyHence there was a need for miniaturised SL sensors thatallowed location independent and if possible continuous real-time SL measurements

Schabmueller et al [38] reported a miniaturised cavity-type sensor chip with three-electrode configuration that wasbuilt using silicon microfabrication technology for continu-ous SL monitoring The sensor has a cavity with fine poreson its floor in which LOx enzyme was immobilised in amatrix of agarose gel and sealed by a self-adhering polyesterfoil (Figures 2(b) and 2(c)) When the sensor was immersed


(a) (b) (c)

Pores

Referenceelectrode

Counterelectrode

Sealing foil

Cavity withworking electrode

Figure 2 Photograph of the packaged lactate chip (a)The front side showing the pores the IrIrOx reference and counter electrode (b)Theback side with cavity and Pt working electrode (c) The back side covered with sealing foil after filing Reprinted from [38] with permissionfrom Elsevier

in a sample solution lactate molecules diffused through thepores in the floor into the cavity whereby the typical lactateenzymatic reaction (see (3)) occurred at 05 V versus irid-iumiridium oxide (IrIrOx) resulting in an amperometricreadout corresponding to the lactate concentration in thesample solution The sensor was optimised for a linear rangeof lactate measurement from 001 to 5mM with sensitivityof 78 nAmMminus1 The sensor was envisioned for real-time invivo monitoring of SL by placing it inside the mouth duringexercise and monitoring the results in a portable wirelessmanner [43]

Another type of sensors developed for SL measurementwas based on the principle of electrochemiluminescence(ECL) [36] The disposable optical sensor employed a LOxbased enzymatic recognition system and luminol as thetransduction system In brief the sensor was prepared byimmobilising all the required reagents in amethocel cellulosemembrane on a commercial screen-printed electrode (SPE)In the presence of lactate (see (3)) the producedH

2O2reacted

with the electrochemically oxidised luminol resulting in ECLemission that was measured by a photocounting head Thesensor exhibited dynamic range of lactate detection from 01to 05mM with DL of 5 120583M within a short measurementtime of 20 s Since the detection range was not within thephysiological range of SL (01 to 25mM) [38] the salivasample required dilution (1 4) with the working buffer beforethe analysis In addition the filtration of the saliva sample apretreatment (04V for 4 s) to oxidise ascorbic acid and theapplication of a blank procedure to correct the error from thepresence of uric acid were necessary to reduce the effect ofinterferent substances

More recently a mouthguard sensor based on printablePrussian-blue (PB) transducer and poly-orthophenylenedi-amine (PPD)LOx reagent layer was reported for continuousSL monitoring [44] The extremely low detection potentialfor H2O2(0042V versus AgAgCl) provided by the PB layer

and the permselective behaviour of the PPD layer minimisedthe effect of possible interferences that are commonly presentin saliva matrix The sensor displayed dynamic range forlactate determination from 01 to 1mM with sensitivity of0553 120583AmMminus1 and DL of 50 120583M It also exhibited goodstability for continuous SL measurement (2 h duration with

repeated measurement every 10min) due to the PPD layerthat protected the sensor surface against coexisting foulingconstituentsThe device was proposed as a practical wearablesensor that could always be in contact with saliva for contin-uous noninvasive monitoring of lactate in real time

Since the material and fabrication process employed inconstructing the aforementioned SL sensors were relativelyexpensive complicated and inappropriate for applicationsin the developing world our group [45] developed a cottonfabric-based electrochemical device (FED) based on carbonmodified with PB (C-PB) electrodes and LOx enzyme forSL measurement The device was fabricated using a simpletemplate method for patterning the three-electrode config-uration and wax patterning technique to create the sampleplacementreaction area on the cotton fabric substrate TheFED exhibited a linear working range for lactate detectionfrom 01 to 5mM with sensitivity of 03169 120583AmMminus1 and DLof 03mM Since the fluid flow in the cotton fabric platformoccurred via capillary forces it was envisioned that the use ofpipettes could be eliminated by incorporating a hydrophiliccotton thread or an extension of the cotton fabric to enableboth sampling and analysis within a single device

Since continuous assessment of lactate is essential forclinical applications and sportsmonitoring two of suchwear-able sensor concepts [38 44] based on saliva samples havebeen reported in the literature However critical assessmentof all potential toxicity and biocompatibility concerns shouldbe addressed in order to allow it to be adapted as a safeand practical wearable sensor to be placed inside the mouth[44] In addition the sensors should also be easily removableand washable to maintain good oral hygiene In order tomake it feasible for long-term continuous SL monitoringit is also crucial for the sensors to exhibit high operationalstability Finally the sensors should be integratedwith amper-ometric circuits and electronics for data acquisition signalprocessing and wireless transmission to provide real-timeinformation of the wearerrsquos health status

4 Salivary Phosphate

Salivary phosphate (SP) via saliva secretion and swallowingprovides a source of endogenous phosphate which at high


levels can contribute to hyperphosphatemia This in turn canresult in cardiovascular calcification among chronic renalfailure patients which can lead to high morbidity and mor-tality especially among haemodialysis patients Thereforeit is important to control serum phosphate through themonitoring of SP level [46ndash48] In addition the significantrelationship existing between SP and oral health can be usedto predict the development of dental caries and formation ofdental calculus [49] SP level is also used as an indicator ofovulation which aids women to predict their fertile periodespecially for the treatment of infertility [50 51]

The conventional instrumental methods for phosphatemeasurement include spectrophotometry and chromatog-raphy However these methods are tedious and time-consuming and need expensive instruments They alsorequire sample pretreatment and the use of carcinogenicchemicals such as molybdenum and antimony tartrate thatcan affect human health and the environment [52]Thereforean amperometric biosensor using pyruvate oxidase (PyOx)enzyme as the biorecognition molecule was developed forrapid SP analysis [53]The PyOx enzyme was immobilised bya Nafion matrix and covered by a poly(carbamoyl) sulfonatehydrogel as a protective layer on the SPE with two-electrodeconfiguration The presence of phosphate in the samplesolution causes the enzymatic generation of H

2O2(see (4))

which results in a current difference proportional to theconcentration of phosphate in the sample The results weremonitored using a potentiostat at 042V versus AgAgClThesensor has a short response time and recovery time of 2 sand 2min respectively as well as a short measurement timeof 4min This provides rapid phosphate analysis comparedto the 10min required for measurement using a commercialphosphate testing kit The sensor also demonstrated linearworking range for phosphate measurement from 75 to625 120583Mwith sensitivity of 52389 nAmMminus1 andDLof 36120583MConsider

Phosphate + Pyruvat +O2PyOx997888997888997888997888rarr Acetylphosphate

+H2O2

+ Carbon dioxide (CO2)

(4)

Although SPmeasurement is important for clinical purposesthere were limited SP biosensors reported in the literatureDue to its serious environmental implications phosphateresearch has been focused mainly on the monitoring ofphosphate concentration in water [52] Nevertheless giventhe promising applications of SP detection this field ofresearch presents potential for further exploration

5 Salivary Alpha-Amylase

Oneof themost important enzymes in saliva is salivary alpha-amylase (sAA) which plays an important role in the initiationof carbohydrate digestion in the oral cavity It also bindsspecifically with high affinity to several oral streptococci lead-ing to bacterial clearance and nutrition that has important

implications for dental plaque and caries formation in theoral cavity [54 55] sAA has been identified as an importantstress biomarker that increases in response to both physicaland psychological stress via interactions with the autonomicnervous system thus making it useful as a biomarker ofautonomic dysregulation [54] Consequently it is used tomeasure the effects of stress-reducing interventions [56 57]sAA concentration is also utilised to determine theATduringexercise training as an alternative to SL measurement [58] Inaddition it is used as a quantifiable biomarker for conditionssuch as pain for objective assessment of pain intensity [59]or for detecting sleepiness [60] Generally the physiologicalrange of sAA in normal subjects is around 10 to 250UmLminus1[61]

In the literature various strategies have been reportedto determine sAA activity using biosensing technology Forexample Yamaguchi et al [62] used a flow-injection typedevice to continuously supply the substrate maltopentaosemeanwhile two enzymes 120572-glucosidase (GD) and GOx wereincorporated to measure the sAA activity based on (5) (6)and (1) Briefly AA enzyme in the saliva sample hydrolysesthe 14-120572-D-glucosidic linkages in the maltopentaose result-ing in maltose and maltotriose (see (5)) This is followedby the reaction of GD enzyme with the prior products toproduce five molecules of D-glucose (see (6)) The typicalglucose enzymatic reaction (see (1)) then takes place resultingin H2O2that was measured using a potentiostat at 06 V

versus Pt counter electrode Conisder

Maltopentaose AA997888997888rarr Maltose +Maltotriose (5)

Maltose +Maltotriose GD997888997888rarr 5D-glucose (6)

The system enabled the measurement of sAA activity from0 to 30UmLminus1 In addition a disposable device whichcollects saliva in about 90 s using capillary action was alsofabricated to eliminate saliva pretreatment step The re-ported system was not designed as a standard device witha working enzyme electrode but as a large analytical sys-tem with complicated construction In the following yearZajoncova et al [63] introduced a relatively simple flow-injection method without precolumn and reduced analyticaltime by adapting mutarotase (MR) enzyme This utilised aperoxide electrode equipped with three different enzymesGD MR and GOx that were immobilised on a cellophanemembrane In summary when maltose which was producedvia starch hydrolysis (see (7)) reacts with GD enzyme itresults in twomolecules of 120572-D-glucose (see (8))This is thenconverted to 120573-D-glucose by MR enzyme (see (9)) Finallythe 120573-D-glucose produced was measured via the glucoseenzymatic reaction (see (1)) that produces H

2O2at 065V

versus AgAgCl electrode Consider

Starch AA997888997888rarr Maltose +Maltotriose + Dextrin (7)

Maltose GD997888997888rarr 2120572-D-glucose (8)

120572-D-glucose MR997888997888rarr 120573-D-glucose (9)


The biosensor has DL of 2 nkatmLminus1 and 05 nkatmLminus1 atamylase reaction time of 5min and 30min respectively Italso exhibited a linear range of current response from 01 to3mMmaltose with a response time of 35 s Without MR thebiosensor was stable for at least twomonths and retained 70of its original activity but the stability was decreased to only 3weeks with MR The storage (dry state at 4∘C) lifetime of thebiosensor was approximately 6 months without MR but only3 months with MR However the biosensor containing MRprovided a smaller relative error (35 for pancreatic amylaseor 39 for sAA) compared to the one without MR (67 forpancreatic amylase or 71 for sAA)

In order to enable location independent mental stressevaluation the development of portable sAA activity mon-itoring devices based on optical detection method was in-vestigated [64ndash66] The first prototype of the portablemonitor comprised a disposable testing strip saliva tran-scription device and an optical analyser [66] The dis-posable testing strip consisted of a collecting strip forsaliva sample collection and a reagent strip incorpo-rated with Gal-G2-CNP (2-chloro-4-nitrophenyl-4-O-120573-D-galactopyranosylmaltoside) chromogen on a testing tape tomeasure the sAA activity The described system requiredsaliva sample to be collected manually using a cotton rollthen condensed using a medical syringe and applied on thecollecting strip When the saliva transcription device wasbent the collecting strip and reagent strip were in contactwith each other hence allowing the sample to be transcribedfrom the collecting strip to the reagent strip At the reagentstrip 2-chloro-4-nitrophenyl (CNP) was hydrolysed in thepresence of AA resulting in a yellow coloured product asshown in

GAL-G2-CNP AA997888997888rarr GAL-G2

+ CNP (White 997888rarr Yellow)(10)

The enzyme reaction would continue until all the substratewas consumed The colour intensity corresponding to thechanges in sAA activity was then measured by inserting thereagent strip into the optical analyser The device was ableto measure sAA activity from a range of 0 to 200UmLminus1by using only 5 120583L of saliva sample within 150 s In thesubsequent work [65] a completely automated sAA activitysystem was fabricated using a disposable test-strip equippedwith built-in collecting and reagent papers as well as anautomatic saliva transfer device The collecting paper wasdirectly inserted into the oral cavity for collection of wholesaliva sample and this was immediately placed onto theautomatic saliva transfer device When a lever was operatedthe reagent paper attached to the back of a spring of the sleevewas pushed towards the collecting paper hence resultingin saliva transfer from the collecting paper to the reagentpaper An alarm was triggered when the saliva transfer wascomplete and the sheet was pulled out of the sleeve allowingthe reflectance to be measured by the optical device Thehand-held monitor took 30 s for saliva sampling and another30 s for saliva transfer and measurement hence allowingmeasurements of sAA activity within a total of 1min by

Figure 3 Portable sAA biosensor comprised hand-held reader anda disposable collector strip Reprinted from [64] with permissionfrom Elsevier

using only 30120583L of saliva sample The system demonstrateda linear range of sAA activity between 10 and 140UmLminus1In order to produce a portable POC biosensor systemfor rapid measurement of sAA level the above-discussedsAA optical monitors were technically improved to allowambulatory care by (i) reducing its overall size (ii) includingtemperature-stable test strips for extended storage time atroom temperature (iii) incorporating pseudosubstrates toslow down the enzyme kinetics to provide an extendeddynamic range (5 to 450UmLminus1) with linear range from10 to 230UmLminus1 (iv) including improvised collector padsto control the sample volume and (v) integrating refinedalgorithms for data processing and digital timedate stampsfor the collected data (Figure 3)The new prototype providedfast sample acquisition (sim10 s) eliminated sample preparationsteps and offered rapid reporting (within 30 s) by using only25 120583L of saliva sample In addition the use of disposableplastic collector strips for saliva sample collection was cost-effective and reduced handling disadvantages caused bycommercial saliva collection devices [64]

The need for a technology that is small and wearable hasalso led to the development of a device with a new designThis consisted of a flat-chip microanalytical enzyme sensorthat behaved as a microelectromechanical system (MEMS)[67] In order to miniaturise the flow cell two enzymaticmembranes containing maltose phosphorylase (MP) and acombination of GOx and POx were immobilised within thesameplanar surface Similar to previouswork [62]maltopen-taose was used as the substrate and a flow-injection systemwas adapted as the analytical system The resulting maltosefrom theAA enzymatic reaction (see (5)) further reactedwithMP enzyme to produce 120572-D-glucose (see (11)) Finally the 120572-D-glucose undergoes the typical glucose enzymatic reaction(see (1)) with POx as amediator and the resulting current wasmeasured at 06V versus Pt counterelectrodeThe sensor wasable to measure sAA activity from 0 to 190UmLminus1 by usingonly 50 120583L of saliva sample Consider

120572-Maltose + Phosphate MP997888997888rarr 120572-D-glucose

+ 120573-D-glucose-1-phosphate(11)


Using a different approach Aluoch et al [68] introducedan amperometric biosensor based on sAA antibody (Ab)and antigen (Ag) interaction The biosensor comprised asalivary Ag (or Ab) layer self-assembled ontoAu electrode viacovalent attachment The molecular recognition between theimmobilised Ag (or Ab) and the sAA proteins was monitoredwith a monodispersed silver layer on the Au electrode whichacted as the electroactive probe The biosensor exhibited alinear range for the determination of AAbetween 3times10minus3 and16 times 10

minus2 ngmLminus1 The DL for the amylase-Ag immobilisedformat was 157 pg mLminus1 while for amylase-Ab immobilisedformat (110000 dilution of amylase Ab) it was 809 ng mLminus1Another alternative using low cost self-sensing piezoelectricmicrocantilever biosensor was also reported [69] The sAAactivity was monitored by measuring the amount of deflec-tion of the microcantilever beam in response to the presenceof sAA molecules The corresponding biochemical signalwas then converted to voltage by using Wheatstone bridgecircuit as the transducer Although the study showed that thebiosensor had capabilities tomeasure sAA the device was nottested using real saliva samples

Another development was a screen-printed disposablesAA biosensor based on Fc as the electron transfer mediator[70] The working principle of the biosensor relied on theenzymatic reaction of AA on starch and GD on the generatedmaltose as in (7) and (8) respectively Finally (1) took placeassisted by Fc at 023V versus saturated calomel electrodeBoth of the enzymes (GD andGOx) were immobilised on theSPEwithNafion filmusing indirect crosslinkingmethodwithGA-bovine serum albumin (BSA) The biosensor exhibited alinear response range for the determination of AA from 60to 840ULminus1 with DL of 17ULminus1 and a response time of lessthan 30 s

Mahosenaho et al [71] also used similar enzymes as [63]inwhich theGDMR andGOx enzymeswere coimmobilisedusing crosslinking method with GA-BSA on SPE modifiedwith PB In this biosensor several starch substrates (partialhydrolysed starch amylose and maltopentaose) were stud-ied but maltopentaose was chosen due to its high solubilityand low molecular weight which improved the specificity ofthe enzyme The reactions that occurred at the biosensor forthe measurement of sAA activity are in the sequence of (5)(8) (9) and (1) The biosensor exhibited a wide linear rangefor the determination of AA from 5 to 250UmLminus1 with DL of5UmLminus1 It also demonstrated good operational and storagestability

In a more recent study an immunosensor based on theimmobilisation of a specific Ab for sAA onto an electropoly-merised graphite electrode coated with poly(3-hydroxyphen-ylacetic acid) was developed [72] The biomolecular interac-tion (affinity of the sAA AbAg) in the device was measuredusing electrochemical impedance spectroscopy (EIS) as thetransducer in which a significantmodification in the Nyquistplot was observed upon addition of the complementary targetwith an increase in the charge transference resistance Theimmunosensor presented the potential for the productionof a label-free sAA biochip unlike the aforementioned bio-sensors that utilised enzymes and chromogen

It is noteworthy that most of the developed electrochem-ical transducers for carbohydrate sensing are amperometricbiosensors However conductometric biosensors have alsodemonstrated their advantages including the simplicity ofthe technology to develop reference electrodes the possibil-ity for miniaturisation and the utilisation of small ampli-tude voltage As a result a conductometric biosensor arraywas proposed recently for simultaneous determination ofcarbohydrates (maltose lactose sucrose and glucose) bySoldatkin et al [73] However conductometric biosensorsmeasurements are susceptible to nonspecific signals fromthe presence of charged substances Although this limitationsignificantly affects the biosensorrsquos accuracy and sensitivityconductometric biosensors should still be considered foreconomic reasons

Compared to other salivary biomarkers an extensiveresearch adapting different biorecognition molecules andtransducers for the development of sAA biosensors has beenreported in the literature This is due to the fact that sAAevidences an excellent capability to quickly and sensitivelyrespond to psychological stress changes thus enabling itto be used as an important index of the sympathetic ner-vous systemThe above-discussed biosensors exhibited rapidsaliva sampling-reporting cycle (sim1min) hence providing atemporal resolution that is useful for time-series psychophys-iological measurements in naturalistic settings In additionthe low saliva sample volume required for the sAA measure-ment also allowed the system to be used among xerostomicindividuals However it would be highly advantageous iffuture research were directed towards the development ofminiaturised wearable sAA biosensors to enable real-timepsychological monitoringThe analytical parameters of someof the catalytic salivary biosensors reported in the literatureare summarised in Table 1

6 Salivary Hormones

Several hormones that are measurable in plasma can also bedetected in saliva including steroids nonsteroids peptidesand protein hormones

Cortisol is a nonpolar steroid hormone that can diffusethrough the lipidmembranes of salivary glands which allowsa good correlation between serum free cortisol and salivarycortisol (SC) levels [74] The measurement of SC is useful asa key indicator of stress similar to sAA [75] for physiologicalstudies [76 77] and screening of Cushingrsquos syndrome [78 79]Paradoxically there is a lack of association between values ofserum and salivary cortisone levels even though it is a neutralsteroid that readily diffuses into saliva Salivary cortisoneconcentration is higher than in serum as cortisol is convertedto cortisone by 11 120573-hydroxysteroid dehydrogenase enzymepresent in salivary glands but it does not have any clinicalsignificance [80 81] The same enzyme also affects othercorticosteroids such as prednisone and prednisolone causingabsence of correlation between serum and salivary levels[82]

Testosterone is an anabolic androgenic steroid thatbehaves as the principal male sex hormone It is also present


Table1Summaryof

thea

nalytic

alparametersfor

catalytic

salivarysensorsreportedin

theliterature

Biom

arker

Biorecognitio

nTransducer

Samplev

olum

e(120583L)

Working

range

Sensitivity

Detectio

nlim

it(D

L)Re

ference

Glucose

GOx

Electro

chem

ical

200

01ndash10mgd

Lminus1

mdashmdash

[31]

GOx

Electro

chem

ical

5001ndash10mgd

Lminus1

mdashmdash

[32]

GOxFclowast

Electro

chem

ical

mdash0ndash

22m

M2145n

A120583molminus1 cmminus2

1120583M

[33]

GOxPO

xTM

BZlowast

Optical

02

0ndash10mgd

Lminus1

mdashmdash

[3435]

GOxPO

xTM

BZlowast

Optical

02

mdashmdash

mdash[19

]

Lactate

LOx

Electro

chem

ical

1000

mdash42

nAmMminus1

mdash[442]

LOx

Electro

chem

ical

mdash001ndash5

mM

78nA

mMminus1

mdash[38]

LOxluminollowast

Electro

chem

iluminescent

5001ndash05m

Mmdash

5120583M

[36]

LOxPBlowast

Electro

chem

ical

mdash01ndash10

mM

0553120583

AmMminus1

50120583M

[44]

LOxPBlowast

Electro

chem

ical

401ndash5m

M03169120583AmMminus1

300120583

M[45]

Phosph

ate

PyOx

Electro

chem

ical

5075

ndash625120583M

52389

nAmMminus1

36120583

M[53]

Alpha-amylase

GDG

Ox

Electro

chem

ical

100

0ndash30

UmLminus

1mdash

mdash[62]

GDM

RGOx

Electro

chem

ical

3501ndash3m

Mmdash

5012

nM(530m

in)

[63]

Gal-G

2-CN

POptical

50ndash

200U

mLminus

1mdash

mdash[66]

Gal-G

2-CN

POptical

3010ndash140

UmLminus

1mdash

mdash[65]

Gal-G

2-CN

POptical

2510ndash230

UmLminus

1mdash

mdash[64]

MPGOxPO

xElectro

chem

ical

500ndash

190U

mLminus

1mdash

mdash[67]

AmylaseA

g-Ablowast

Immun

oelectrochem

ical

mdash3times10minus3 ndash16times10minus2ng

mLminus

1mdash

157p

gmLminus1

[68]

GDG

OxFclowast

Electro

chem

ical

mdash60ndash8

40UmLminus

1mdash

17UmLminus1

[70]

GDM

RGOxPBlowast

Electro

chem

ical

mdash5ndash250U

mLminus

114nA

Uminus1

5UmLminus1

[71]

lowastTh

ebiorecognitio

nmoleculeislistedtogether

with

thechromogen

that

provides

thechange

ofcolour

foro

pticaldeterm

inations

with

theredo

xmediators

that

facilitateele

ctrons

transfe

rfor

electrochem

ical

determ

inations


in women enabling the production of female hormoneoestrogen [83] Similar to other steroid hormones salivarytestosterone (ST) is in free (bioavailable) form as it is neitherbound to proteins nor conjugated allowing it to be measuredeasily without dialysis process before assaying [84] Thesignificant correlation between serum testosterone and STlevels supports it as an attractive noninvasive biomarkerfor assessing serum testosterone concentration [84ndash88] Itis important to measure ST levels for behavioural research[89] sports endocrinology [90] and diagnosis of medicalconditions such as late-onset hypogonadism and testosteronedeficiency syndrome [84 91] and in determining the andro-genic function of prostatic carcinoma patients after medicalor surgical orchiectomy [92] Szydlarska et al [93] alsoshowed that the ratio of salivary androstenedionesalivarytestosterone is a good indicator of hyperandrogenism aprimary symptom of polycystic ovary syndrome

Female sex steroid hormones such as salivary proges-terone (SPg) and estradiol concentrations are alsomeasurablein saliva These are useful for determining menstrual cycleprofiles for fertility andpregnancymonitoring amongwomen[94 95] The measurement of progesterone concentrationis also useful in the diagnosis of certain medical condi-tions such as luteal phase defects impending abortion andectopic pregnancy that can lead to sterility In additionthe effect of drugs such as oral contraceptives superovula-tory drugs oestrogen replacement therapy medication andgonadotropin-releasing hormone analogues can be closelymonitored from progesterone levels [94]

Nonsteroid hormones such as catecholamine can alsobe identified in saliva ranging from 250 to 800 pgmLminus1However it does not correlate well with serum due touncertain origin making it unsuitable as an index for generalsympathetic tone [96 97] However dihydroxyphenylglycola metabolite of catecholamine shows a good correlationwith plasma level [98] In addition salivary melatonin alsoshows a highly significant and reproducible correlation withplasma melatonin concentration hence making it a reliablealternative to venipuncture for pineal physiology studiesamong newborn infants [99]

Due to the large dimensions of protein plasma hormonesit is difficult for them to pass through the salivary glandsby passive diffusion Thus it is challenging to detect thesehormones in saliva [1 2] However these hormones aredetectable if they are directly produced by salivary glandsAn example is leptin a protein hormone that is producedstored and secreted by salivary glands and expressed in theoral mucosa [100]

Several detection techniques have been evaluated toquantify SC concentration such as chromatography [101102] immunoassays [103ndash105] and optical [106] and electro-chemical immunosensors [107] Since chromatographic andimmunoassay techniques are time consuming and expensiveand involve laboratory screening methods they are notattractive for POC diagnostics Typically cortisol biosensorsare immunosensors since they use the specificity of Ag-Abinteractions Nevertheless in some cases the use of enzymesis still required to provide a measurable analytical signal

For example an immunoelectrochemical sensor based onalkaline phosphatase (AP) enzymewas developed tomeasureSC concentration [108] In this sensor cortisol capturedAbs were immobilised on functionalised microfabricated Auelectrodes that were encased within a microfluidic chamberWhen the AP enzyme which was attached to the cortisol Agvia the detector Abs reacted with p-nitrophenyl phosphatesolution p-nitrophenol was generated and detected as anoxidative peak between 09 and 11 V versus Ag pseudorefer-ence electrodeThemagnitude of the anodic peak in the cyclicvoltammetry varied linearly with cortisol concentration andhence this was used to quantify cortisol in real saliva samplesThe sensor accuratelymeasured cortisol in the collected salivasamples to a concentration of 076 nM (021 ngmLminus1)

In another study a surface plasmon resonance (SPR)biosensor system in which cortisol was detected by com-petitive assay combined with an in-line filtering flow cellprovided results in less than 10min making it suitablefor analysis in the field and in emergency rooms [109]Although the system exhibited a detection range between15 and 10 ngmLminus1 (54 and 36 nM) with DL of 10 ng mLminus1(36 nM) for SC measurement it could be further extendedfor high-end detection range by increasing the concentrationof Ab or diluting the sample solution Mitchell et al [74]also developed a microfluidic SPR biosensor system thatutilised competitive assay for SC detection The biosensoremployed cortisol-linker conjugate covalently immobilisedon the sensing surface as a coating agent In this system thesample solution was mixed with the primary Ab and injectedinto the flow-through biosensor where it competed with thesurface immobilised cortisol for binding to the Ab To furtherenhance the biosensor signal the surface-bound primary Abwas attached to a secondary Ab by increasing bound mass onthe surface In buffer the system presented DL of 13 pgmLminus1with sensitivity of 72 RUmLngminus1 The immunoassay wasoptimised to cover the physiological range of SC between91 and 934 pgmLminus1 but higher concentration samples canbe diluted if necessary The immunoassay exhibited DLof 49 pgmLminus1 and sensitivity of 162 RUmLngminus1 in salivasamples Since only 50 120583L of saliva per sample replicate wasrequired the SC measurement for each sample could becompleted in 10min

While the described biosensors reported excellent sen-sitivity DL and response time the need for user-friendlydevices has led to the investigation of disposable devices Animmunochromatographic test strip based biosensor com-posed of a disposable test strip and monitor was developedfor this purpose [110] In this biosensor a GOx-cortisolconjugate was synthesised and used for the specific Ag-Abreactions In brief when a sample solution was introducedon the sample pad the solution was filtered and the GOx-cortisol conjugate in the conjugate pad was dissolved At thetest-line the cortisol Ags in the solution were immobilisedwith cortisol Ab forming an Ag-Ab reaction Thus theconcentration of the trapped GOx-cortisol conjugate wasinversely proportional to the cortisol concentration in thesolution When GOx enzyme assay was applied on thestrip a red coloured band appeared and its intensity was


measured using an optical reader The biosensor allowedcortisol measurement in the range of 1 to 10 ngmLminus1 within atotal measurement time of 25min The system demonstratedits potential utility for a SC POCmeasurement system Usinga similar working concept (competitive reaction betweencortisol in the sample solution and a GOx-labeled corti-sol conjugate) Yamaguchi et al [111] reported a cortisolimmunosensor based on electrochemical detection methodThe measured current was inversely related to the cortisolconcentration in the sample solution The immunosensorallowed SC measurement in the range between 01 and10 ngmLminus1 with measurement time of 35min

Other electroanalytical techniques have been used forthe development of immunosensors Arya et al [112] re-ported an impedimetric cortisol immunosensor using dithi-obis(succinimidylproprionate) (DTSP) self-assembled mon-olayer functionalised Au microelectrode array The immun-osensor exhibited linear behaviour for cortisol concentra-tion in the range of 1 pM to 1 120583M with DL of 1 pMThe remarkable electrochemical properties of carbon nan-otubes (CNT) have led to the use of these in the fieldof biosensors such as the immunosensor based on single-walled carbon nanotube (SWCNT) chemiresistive transducerfor SC measurement [113] The CNT were functionalisedwith a cortisol analog (cortisol-3-CMO-NHS ester) that wasligated with a monoclonal anti-cortisol Ab The presence ofcortisol displaced the anti-cortisol Ab hence resulting ina corresponding decrease in the resistanceconductance ofthe CNT-biomolecule hybrid The immunosensor exhibitedan inverse relationship to cortisol concentration over arange of 1 pgmLminus1 to 1000 ngmLminus1 that was linear from1 pgmLminus1 to 10 ngmLminus1 with sensitivity in the linear rangeof 1397 ngmLminus1 and DL of 1 pgmLminus1 It also demonstratedexcellent binding selectivity for cortisol even in the presenceof structurally similar steroids such as 21-hydroprogesterone

Besides exploring properties of the immobilisationmatrix studies have also been focused on improving thesensitivity and stability of immunosensors More recentlysemiconductor inorganic material has been applied asa successful immobilisation matrix [114 115] For instanceone-dimensional zinc oxide (ZnO) nanorods (ZnO-NRS)and two-dimensional ZnO nanoflakes (ZnO-NFs) surfaceswere modified to immobilise anti-cortisol Ab in order todevelop an electrochemical cortisol immunosensor [115]The sensitivity of the ZnO-NRS and ZnO-NFs electrodesestimated using electrochemical impedance spectroscopymethod was 3078 kΩMminus1 and 540ΩMminus1 respectively TheDL for both the electrodes was obtained at 1 pM

As in the case of cortisol testosterone biosensors areimmunosensors Mitchell and Lowe [87] reported a SPRbiosensor tomeasure testosterone in awide range ofmatricesIn this study an oligoethylene glycol linker conjugate oftestosterone was synthesised and applied as a coating agenton the sensing surface using covalent bond immobilisationmethod The sensing surface was highly stable hence allow-ing a high degree of reusability The biosensor was furtherimproved using both secondary Ab and gold nanoparticlesignal enhancement method which increased the assayrsquos

signal sensitivity 125-fold compared with primary Ab aloneThe enhanced assay demonstrated a linear response range oftestosterone detection from 25 to 250 pgmLminus1 with DL of37 pgmLminus1 for standards in running buffer and 154 pgmLminus1in stripped human saliva matrix The device was capable ofmeasuring ST in male saliva across the broad physiologicallyrelevant range (29ndash290 pgmLminus1) in less than 13min makingit suitable as a noninvasive near real-time ST biosensor

As concluded from all the reviewed detection techniquesin this section electrochemical immunosensors providedlow DL high sensitivity and rapid analysis compared tooptical sensors However one important issue that has notbeen investigated is the impact of environmental factors onthe antibody stability Nevertheless the miniaturisation andautomation of electrochemical immunosensors to measureSC level present great potential for POC diagnostics technol-ogy

7 Salivary Antibodies

Saliva is also used for the detection of Abs that fight a numberof viral fungal and parasitic agents specific bacteria andallergy reactions There are two major Ab classes available insaliva namely immunoglobulin A (IgA) and immunoglobu-lin G (IgG) Generally IgA is synthesised by plasma cells insalivary glands and then exported by an epithelial receptor-mediated mechanism Meanwhile IgG is mainly derivedfrom serum via passive diffusion and a minor fraction isoriginated from glandular gingival or tonsillar plasma cells[116]

The bacterium Helicobacter pylori is the major cause ofgastrointestinal disorders such as chronic active gastritis andduodenal and gastric ulceration [117] It is also related tothe development of gastric carcinoma [118] and mucosal-associated lymphoid tumours [119] Several studies have con-firmed that the concentration of salivary IgG antibodies thatcombat H pylori can offer a noninvasive screening methodof its infection However it has several limitations comparedto conventional gastric histological and serological studiesthus making it useful only in certain patient subpopulationsor in specific clinical contexts [120ndash122] Leptospirosis whichis caused by the bacterium Leptospira is another bacterialinfection that can be diagnosed from the detection of spe-cific immunoglobulin M (IgM) class antibodies in saliva[123]

Saliva is also widely used as a diagnostic tool for humanimmunodeficiency virus (HIV) and hepatitis C virus infec-tion as it outweighs blood testing for Ab screening particu-larly for home testing [124ndash130] Since HIV infection reducesoral defence mechanism and may affect mucosal integrityHIV patients are highly susceptible to Candida albicansfungal infection that causes oral candidiasis disease Thepattern of two subclasses of salivary IgA that includes IgA1and IgA2 changes duringC albicans fungal infectionmakingit a potential biomarker to monitor the progression of HIVand acquired immunodeficiency syndrome (AIDS) infection[131 132]


In addition salivary antibodies concentration also pre-sents diagnostic value for intestinal infection due to par-asitic agents such as Entamoeba histolytica [133 134]Trichuris trichiura Ascaris lumbricoides and hookworms[135] Another prominent infectious parasitic organism isToxoplasma gondii that causes toxoplasmosis disease Thedisease is normally asymptomatic in healthy individualsbut causes abortion among pregnant patients or mortalityin immunosuppressed individuals such as AIDS patientsStroehle et al [136] showed that specific anti-T gondii salivaryIgG concentration can be used for the diagnosis of toxoplas-mosis disease Besides that IgG antibodies to Ags of Taeniasolium metacestodes infection can also be detected in salivasamples of intracerebral cysticercosis patients thus making ituseful for the diagnosis of neurocysticercosis disease [137]

The broad diagnosis range that salivary antibodies canprovide has meant that they are seen as potentially usefulin clinical settings As such there has been an increase inthe number of studies on biosensor technologies and theirdevelopment A piezoelectric quartz crystal immunosensorcomprised of a quartz piezoelectric crystal an oscillatorand a frequency counter was developed to monitor anti-bodies in diluted human saliva sample [138] Briefly theantibodies against human immunoglobulin A (anti-IgA)were immobilised using two different techniques adsorptionand covalent bond method onto the Au electrode surfaceof the crystal The crystal was then oscillated at a basic fre-quency of 9MHz by an oscillator Meanwhile the oscillationfrequency corresponding to the immunoreactions betweenthe immobilised anti-IgA and IgA in the sample solutionwas measured using the frequency counter and translatedto a computer The results revealed that the covalent bondimmobilisation method has better repeatability compared tothe adsorption method Subsequently the immunoreactionsbetween the immobilised anti-IgA using the covalent bondmethod and diluted human saliva IgA were monitored inreal time providing a maximum frequency change at about1000 s The immunosensor showed a linear relationshipbetween the maximum frequency change of human salivaand the concentration of standard human IgA Finally theamount of Abs in human saliva sample measured usingELISA technique was compared to the results obtained for a100 times diluted solution of the same human saliva sampleusing the immunosensorThe resultswere in good agreementthus confirming the accuracy of the method

In another study Au SPEs have been used to constructpolytyramine- (Ptyr-) based immunosensors to target Strep-tococcus pyogenes bacteria [139] The biotinyl tagged wholeantibodies against S pyogenes were conjugated to Ptyr aminegroup via biotin-NeutrAvidin coupling The sensor showedlinear response of 100 to 105 cells per 10 120583L in cumulativeincubation and 100 to 104 cells per 10 120583L in single-shotincubation which covered the pathogenic load of S pyogenesinfection that is around 106 cells mLminus1 The sensor wasalso used to detect S pyogenes infection in saliva in whichit exhibited low crossreactivity and high selectivity thusdemonstrating its capability to be used in complex biologicalsamples such as saliva

Electrochemical biosensors have also been proven to be apromising platform for the detection of target Abs with highsensitivity and selectivity [140 141] Recently electrochemicalpeptide-based (E-PB) sensors were also fabricated for anti-HIV antibodies detection [140] Several surface modificationstrategies have been used to fabricate E-PB sensors to dateMcQuistan et al [142] reported E-PB HIV sensor fabricationusing thiolated oligonucleotides as passivating diluents andits applicability was examined in synthetic human salivaAlthough the researchers fabricated several sensitive andselective electrochemical biosensors to target salivary Absdetection there is still a need for improvement In thiscase electrochemical immunosensors construction shouldbe optimised to achieve higher sensitivity

8 Salivary Cancer Biomarkers and Biosensors

Salivary biomarkers have been identified that can potentiallyprovide useful information for clinical diagnosis and progno-sis of a variety of cancers (oral pancreatic lung breast andliver)

The sixth most common cancer worldwide is head andneck cancer with 40 of these cases being cancer of theoral cavity Due to the direct contact between saliva and oralcancer lesions various salivary proteomes have been reportedin the literature as potential biomarkers for oral cancerdetection such as interleukin-8 (IL-8) [143ndash145] tumournecrosis factor-alpha and salivary transferrin [146] On theother hand salivary soluble CD44 Ag can be used as abiomarker for head and neck squamous cell carcinoma [147]while the serum circulatory tumour markers Cyfra 21-1 [148149] tissue polypeptide Ag cancer Ag 125 [148] and salivaryzinc finger protein 510 peptide [150] were identified as oralsquamous cell carcinoma-related salivary biomarkers

Pancreatic cancer is the fourth leading cause of cancer-related mortality and second most frequent gastrointestinalmalignancy Zhang et al [151] carried out a prospectivesample collection and retrospective blinded validation toevaluate the performance and translational utilities of salivarytransciptomic biomarkers for the noninvasive detection ofresectable pancreatic cancer Results showed that a combi-nation of four messenger RNA biomarkers namely KRASMBD3L2 ACRV1 and DPM1 in saliva supernatant candistinguish pancreatic cancer patients from healthy subjectsIn another study various lung cancer biomarkers present insaliva were identified to differentiate lung cancer patientsfrom healthy subjects [152 153]

Another example of the use of salivary biomarkers forthe diagnosis of systemic cancer can be seen in breast cancerresearch A salivary protein product of the oncogene c-erbB-2 and cancer Ag 15-3 (CA15-3) was reported to be usefulfor the early detection and measurement of breast cancerpatientsrsquo response towards chemotherapy andor surgicaltreatment of the disease [154ndash156] In another study itwas shown that salivary protein factors such as vascularendothelial growth factor epidermal growth factor andcarcinoembryonic Ag were elevated in breast cancer patients


compared to healthy subjects hence making it a possiblebiomarker for breast cancer detection [157]

Since saliva biomarkers have shown to be able to diagnosecancer different biosensor technologies have been investi-gated to determine those biomarkers A surface immobilisedoptical protein sensor was developed to detect IL-8 proteinan oral cancer salivary biomarker [144] The sensor hassimilar DL (11 pM) to ELISA assay despite eliminating thecommon enzymatic amplification employed in commercialIL-8 ELISA assays In addition ELISA and the sensor showedsimilar diagnostic performances when measuring IL-8 inclinical saliva samples Nevertheless the sensor demon-strated better capability for detecting true positives in cancerpatients whilst ELISA showed itself to be slightly better atdifferentiating true negatives By using confocal optics toreduce the optical noise the DL of the sensor was furtherextended to 40 fM which is the lowest reported sensitivityfor IL-8 detection In addition an excellent linearity of IL-8concentrations from 6 fM to 12 pM was observed The highsensitivity of the confocal optical protein sensor makes itsuitable to be applied for a variety of biomarkers especiallythose present in very low concentrations

In another study a SPR biosensor based on thinfilm Auzinc oxide (AuZnO) was developed using aradiofrequency sputtering system (1356MHz) for the detec-tion of CA15-3 a breast cancer biomarker in human saliva[158] The performance of the thin film SPR system wascompared with a Biacore SPR system for the detection ofsaliva CA15-3 The Biacore SPR system allowed the detectionof higher concentrations of saliva CA15-3 but the sensitivitydropped at lower concentrations (lt75UmLminus1) On the otherhand the thin film SPR system showed a linear responseto saliva CA15-3 from 25 to 200UmLminus1 thus covering therelevant saliva CA15-3 concentration range for both healthyindividuals and malignant breast cancer patients Hence itwas deemed suitable for the clinical diagnosis of breast cancerprogression

In a more recent study a label free fluorescent biosensorwas developed based on nuclease assisted target and recy-cling thioflavin T- (ThT-) induced quadruplex formation foramplified short DNA species of c-erbB-2 oncogene (T1) [159]Since ThT signal transducers amplify the signal from shortDNA the sensor was designed for early stage breast cancerdetectionwith high sensitivity specificity speed and low costcompared to other reported methods As a result T1 wasdetected within a linear range of 100 fM to 1 pM with DL of20 fM

Due to low levels of cancer biomarker antigens in salivathere is a compelling need to develop a more accuratehighly sensitive and specific biosensor Overall the use ofimmunosensors for the determination of salivary hormonesantibodies and cancer biomarkers can provide relativelyquick and easy monitoring for patients that require multiplediagnoses and continuous monitoring Although more workis necessary to improve the incubation time required andthe sensitivity range these biosensors have the potential tobe used as home care devices providing the patient with

a preliminary diagnosis that could then be corroborated inclinics and hospitals

The development of highly sensitive and selective biosen-sors for the detection of salivary biomarkers has beenemphasised for disease diagnosis in effective and noninvasivemethods However detection of a single biomarker is notsufficient for accurate medical diagnosis Therefore effortshave been made to develop assays or biosensors for mul-tiplexed detection of different types of salivary biomarkersThe first multiplexed electrochemical sensor for the deter-mination of salivary biomarkers for oral cancer detectionwas reported by Wei et al [160] Their results proved thatthe multiplex detection of both IL-8 mRNA and proteinhelps to provide a more accurate diagnosis for oral cancerdetection Nevertheless complications have been reportedwhen using multiplexed sensors to detect various salivarybiomarkers simultaneously due to low levels of biomarkersin saliva The integration of microfluidic systems has beeninvestigated to overcome the difficulties of multiplex ELISAmethods For example a microfluidic biosensor for thedetermination of three important serum and saliva cancerbiomarkers namely carcinoembryonic antigen (CEA) can-cer antigen 125 (CA125) andHer2Neu (C-erB-2) was devel-oped using quantum dots (QDs) [161] The semiconductorQD nanoparticles presented strong intensity and long-termphotostability Hence they can be used to overcome thesometime indistinguishable target specific signals from low-level salivary biomarkers Besides that a study carried out byJokerst et al verified that the integration of semiconductornanoparticle QDs and amultianalytical nanobiochip reducedthe DLs by half compared to ELISA The capability of thesystem for multiplexing was evaluated via the spatial beadsarrangement on the chipThe specific and nonspecific signalswere expressed from three different specified beads withHer-2Neu CEA and CA125 antibodies The nonspecific signalwas reported to be less than 5 of the specific signal for allthree different beads Thus the results demonstrated that thenanobiochip sensor served as a specific andmultiplexmethodfor the determination of multiple salivary biomarkers fromsaliva and serum with sensitive signals and low DL withina short time [161] Biosensors for multiplexed detectionof different types of salivary biomarkers are still in earlystage but present the potential to significantly change cancerdiagnosis and preventionThe early diagnosis of cancer couldgreatly reduce the mortality rates of the disease This woulddefinitely be a significant breakthrough for the fight againstcancer since a salivary biosensor could be easy to use andeconomical enough to be a home care device or even awearable technology

Some of the immunosensors reported in the literature todetermine biomarkers in saliva are summarised in Table 2

9 Conclusion

The significance of salivary biomarkers for clinical diagnosisand therapeutic applications has been reported with addi-tional focus on technologies and biosensing platforms forscreening these biomarkers


Table2Summaryof

ther

eportedSL

immun

osensorsanalyticalparameters

Biom

arker

Biorecognitio

nTransducer

Samplev

olum

e(120583L)

Working

range

Sensitivity

Detectio

nlim

it(D

L)Re

ference

Cortisol

CortisolAg-Ab

AP

Immun

oelectrochem

ical

30mdash

mdash021ng

mLminus1

[108]

Cortisolconjugate-Ab

Optical

mdash15

ndash10n

gmLminus

1mdash

10ng

mLminus1

[109]

Cortisol-link

erconjugate-Ab

Optical

5091ndash934

pgmLminus1

162R

UmLngminus1

49pg

mLminus1

[74]

GOx-cortiso

lcon

jugateA

g-Ab

Optical

100

1ndash10ng

mLminus

1mdash

mdash[110]

GOx-cortiso

lcon

jugateA

g-Ab

Immun

oelectrochem

ical

4001ndash10ng

mLminus

1mdash

mdash[111]

CortisolAg-Ab

Immun

oelectrochem

ical

mdash1p

Mminus1 120583

M1165

kΩMminus1

1pM

[112]

Cortisolanalog-anti-c

ortisolAb

Fieldeffecttransistorschem

iresistors

mdash0001ndash10ng

mLminus

11397n

gmLminus1

1pgm

Lminus1

[113]

Cortisol

conjugate-BS

AA

nti-c

ortisolAb

Immun

oelectrochem

ical

10100p

Mto

100n

M540Ω

Mminus1

1pM

[115]

Testo

sterone

Testo

sterone-link

erconjugate-Ag-Ab

Optical

mdash25ndash250

pgmLminus

145

RUmLngminus1

154pg

mLminus1

[87]

Immun

oglobu

linA(Ig

A)

IgA-

antiIgA

Piezoelectric

1000

0mdash

mdashmdash

[138]

SAG1antigen

mdashmdash

mdashmdash

mdash[162]

IgGHIV

target

Electro

chem

ical

mdashmdash

mdash1n

M[14

2]Streptococcus

pyogenes(S

pyogenes)b

acteria

Anti-S

pyogenes

Ab-Ptyr-biotin-N

eutrAv

idin

Immun

oelectrochem

ical

mdash100to

105cells

per10120583

Lmdash

mdash[139]

Interle

ukin-8

(IL-8)

IL-8

capturep

robe-IL-8

targetFluorescent

Optical

506fMndash12p

Mmdash

40fM

[144]

IL-8

capturep

robe-IL-8

targetFluorescent

Optical

20mdash

mdash08p

M[159]

Cancer

antig

ens

15-3

(CA15-3)

Anti-C

A15-3

AbOptical

mdash25ndash200UmLminus

1mdash

mdash[158]

Anti-C

A153Ab

Optical


10001ndash001Um

L0001U

mL

[163]

IL-8

mRN

Aandproteinprob

eElectro

chem

ical

mdash5fMndash50p

M

10ndash12500

pgm

L39fM

74pgm

Lmdash

[160]


Most of the biosensors reviewed have reported excellentsensitivity detection limit and response time Moreoverefforts have been made to miniaturise devices integratedwith sample-handling This allows portability which in turnprovides rapid point-of-care diagnosis and reduces costs(travel cost to the hospital and hospital stay) a highly bene-ficial characteristic especially for applications in developingcountries The devices could also be conveniently used ashome care devices providing the patient with a preliminarydiagnosis that could then be corroborated in healthcaresettings However these miniaturised devices have currentlybeen limited to the sampling and detection of a small groupof salivary biomarkers mainly SG and sAA This has createda need to produce devices for measuring a wider rangeof salivary biomarkers One proposed recommendation isthe development of biosensing devices that combine bothsampling and analysis within a hand-held device in a user-friendly manner such as dental floss and toothbrush Thisprocess would not require supervision of a trained healthcareworker thus allowing it to be easily performed and location-independent

In some cases there is a demand for continuous assess-ment of biomarkers to monitor the patientrsquos health conditionand progression after treatment This has led to increasinginterest in wearable sensor technologies that can be placedinside the patientrsquos mouth However several factors need tobe taken into consideration in the design and implementationof these sensors (i) potential toxicity and biocompatibility(ii) easy removability and washability for hygiene purposesand (iii) high operational stability Additionally the sensorsshould be integrated with circuits and electronics for dataacquisition signal processing and wireless transmission toprovide real-time information of the wearerrsquos health status

Based on the reported devices it can be observed thatvariousmodifications to the sensors have been investigated inorder to provide very low detection limit and highly sensitiveresults especially in the case of immunoassays for detectionof salivary hormones antibodies and cancer biomarkersTherefore it is envisioned that the rapidly evolving fieldsof proteomics bioengineering and analytical chemistry willprovide an impact on the development of a well-equippedand reliable sensing platform for saliva-based diagnosis inthe near future Meanwhile the significance of biosensors formultiplexed salivary biomarkers detection in cancer researchwhich can provide greater accuracy compared to a singlebiomarker approachwill further fuel the research in this area

Although biosensors have long been investigated asdiagnosis systems only in the last decade has this researchfocused more intensely on devices that are wearable easyto use and minimally invasive for applications as point-of-care technology Nanotechnology and materials science haverevolutionised the field of clinical devices Biosensors cannow be easily miniaturised they are more stable and robustand present higher degree of biocompatibility allowingcontact with the sample in situ Since saliva presents goodcorrelationwith various plasma biomarkers and it is relativelyeasy to sample an increasing number of saliva biosensorsinvestigations can be expected in the following years

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgments

The authors would like to thank Universiti TeknologiMalaysia (GUP Grant Vote no 01H78) and the Ministry ofHigher Education (MOHE) for the funding of this researchwork They would also like to express our gratitude toProfessor Mohd Roji Sarmidi from Faculty of Chemicaland Natural Resources Engineering Universiti TeknologiMalaysia for his invaluable suggestions on the work of thispaper

References

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[2] S Chiappin G Antonelli R Gatti and E F de Palo ldquoSalivaspecimen a new laboratory tool for diagnostic and basicinvestigationrdquoClinica Chimica Acta vol 383 no 1-2 pp 30ndash402007

[3] E Kaufman and I B Lamster ldquoThe diagnostic applications ofsalivamdasha reviewrdquo Critical Reviews in Oral Biology amp Medicinevol 13 no 2 pp 197ndash212 2002

[4] G G Guilbault G Palleschi and G Lubrano ldquoNon-invasivebiosensors in clinical analysisrdquo Biosensors and Bioelectronicsvol 10 no 3-4 pp 379ndash392 1995

[5] V Shetty and M Yamaguchi ldquoSalivary biosensors for screen-ing trauma-related psychopathologyrdquo Oral and MaxillofacialSurgery Clinics of North America vol 22 no 2 pp 269ndash2782010

[6] Y H Lee andD TWong ldquoSaliva an emerging biofluid for earlydetection of diseasesrdquoTheAmerican Journal ofDentistry vol 22no 4 pp 241ndash248 2009

[7] R L Hodinka T Nagashunmugam and D Malamud ldquoDetec-tion of human immunodeficiency virus antibodies in oralfluidsrdquo Clinical and Diagnostic Laboratory Immunology vol 5no 4 pp 419ndash426 1998

[8] T F Robles V Shetty C M Zigler et al ldquoThe feasibility ofambulatory biosensor measurement of salivary alpha amylaserelationships with self-reported and naturalistic psychologicalstressrdquo Biological Psychology vol 86 no 1 pp 50ndash56 2011

[9] L Micheli D Moscone and G Palleschi Biosensors for MedicalApplications Elsevier Science 2012

[10] M-S Soares M-M Batista-Filho M-J Pimentel I-A Passosand E Chimenos-Kustner ldquoDetermination of salivary glucosein healthy adultsrdquoMedicinaOral PatologiaOral y Cirugia Bucalvol 14 no 10 pp e510ndashe513 2009

[11] A Azizi and A Modaberi ldquoThe correlation of blood glucosewith salivary glucose level in diabetic patientsrdquo Journal ofIslamic Dental Association of Iran vol 25 no 4 pp 274ndash2772014

[12] L S Vagish Kumar ldquoSalivary glucose levels and its correlationwith serum glucose and glycemic status in diabeticsrdquo CukurovaMedical Journal vol 39 no 1 pp 7ndash18 2014


[13] S Aydin ldquoA comparison of ghrelin glucose alpha-amylase andprotein levels in saliva from diabeticsrdquo Journal of Biochemistryand Molecular Biology vol 40 no 1 pp 29ndash35 2007

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[21] A Gupta N Gupta N Jain R Garg G Atreja and S S WalialdquoDevelopment of noninvasive procedure for monitoring bloodglucose level using gingival crevicular bleedingrdquo StomatoloskiGlasnik Srbije vol 60 no 3 pp 124ndash128 2013

[22] H Kaur B Singh and A Sharma ldquoAssessment of blood glucoseusing gingival crevicular blood in diabetic and non-diabeticpatients a chair sidemethodrdquo Journal of Clinical and DiagnosticResearch vol 7 no 12 pp 3066ndash3069 2013

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[35] M Yamaguchi Y Kawabata S Kambe et al ldquoNon-invasivemonitoring of gingival crevicular fluid for estimation of bloodglucose levelrdquoMedical and Biological Engineering and Comput-ing vol 42 no 3 pp 322ndash327 2004

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for physiological studies and diagnostic strategiesrdquo BrazilianJournal of Medical and Biological Research vol 33 no 10 pp1171ndash1175 2000

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[78] T Carroll H Raff and J W Findling ldquoLate-night salivarycortisol measurement in the diagnosis of Cushingrsquos syndromerdquoNature Clinical Practice Endocrinology and Metabolism vol 4no 6 pp 344ndash350 2008

[79] M Trilck J Flitsch D K Ludecke R Jung and S PetersennldquoSalivary cortisol measurementmdasha reliable method for thediagnosis of Cushingrsquos syndromerdquo Experimental and ClinicalEndocrinology and Diabetes vol 113 no 4 pp 225ndash230 2005

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[85] A L Arregger L N Contreras O R Tumilasci D R Aquilanoand EM L Cardoso ldquoSalivary testosterone a reliable approachto the diagnosis ofmale hypogonadismrdquoClinical Endocrinologyvol 67 no 5 pp 656ndash662 2007

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[95] B K Gandara L Leresche and L Mancl ldquoPatterns of salivaryestradiol and progesterone across the menstrual cyclerdquo Annalsof the New York Academy of Sciences vol 1098 pp 446ndash4502007

[96] A Marini and E Cabassi ldquoLa saliva approccio complementarenella diagnostica clinica e nella ricerca biologicardquo AnnaliFacolta Di Medicina Veterinaria Di Parma vol 23 pp 295ndash3112002

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[98] B Kennedy E Dillon P J Mills and M G Ziegler ldquoCate-cholamines in human salivardquo Life Sciences vol 69 no 1 pp 87ndash99 2001

[99] S Bagci A Mueller J Reinsberg A Heep P Bartmann andA R Franz ldquoUtility of salivary melatonin measurements inthe assessment of the pineal physiology in newborn infantsrdquoClinical Biochemistry vol 43 no 10-11 pp 868ndash872 2010

[100] M Groschl M Rauh R Wagner et al ldquoIdentification ofleptin in human salivardquo The Journal of Clinical Endocrinologyamp Metabolism vol 86 no 11 pp 5234ndash5239 2001

[101] P Dhar ldquoMeasuring tobacco smoke exposure quantifyingnicotinecotinine concentration in biological samples by col-orimetry chromatography and immunoassaymethodsrdquo Journalof Pharmaceutical and Biomedical Analysis vol 35 no 1 pp155ndash168 2004

[102] I Perogamvros L J Owen J Newell-Price D W Ray P JTrainer and B G Keevil ldquoSimultaneous measurement of corti-sol and cortisone in human saliva using liquid chromatography-tandemmass spectrometry application in basal and stimulatedconditionsrdquo Journal of Chromatography B Analytical Technolo-gies in the Biomedical and Life Sciences vol 877 no 29 pp 3771ndash3775 2009

[103] R A Dressendorfer C Kirschbaum W Rohde F Stahl andC J Strasburger ldquoSynthesis of a cortisol-biotin conjugate andevaluation as a tracer in an immunoassay for salivary cortisolmeasurementrdquo Journal of Steroid Biochemistry and MolecularBiology vol 43 no 7 pp 683ndash692 1992

[104] W S Gozansky J S Lynn M L Laudenslager and W MKohrt ldquoSalivary cortisol determined by enzyme immunoas-say is preferable to serum total cortisol for assessment ofdynamic hypothalamic-pituitary-adrenal axis activityrdquo ClinicalEndocrinology vol 63 no 3 pp 336ndash341 2005

[105] H Raff P J Homar andD P Skoner ldquoNew enzyme immunoas-say for salivary cortisolrdquo Clinical Chemistry vol 49 no 1 pp203ndash204 2003

[106] J Mitchell ldquoSmall molecule immunosensing using surfaceplasmon resonancerdquo Sensors vol 10 no 8 pp 7323ndash7346 2010

[107] K Sun N Ramgir and S Bhansali ldquoAn immunoelectrochem-ical sensor for salivary cortisol measurementrdquo Sensors andActuators B Chemical vol 133 no 2 pp 533ndash537 2008



[109] R C Stevens S D Soelberg S Near and C E Furlong ldquoDetec-tion of cortisol in saliva with a flow-filtered portable surfaceplasmon resonance biosensor systemrdquo Analytical Chemistryvol 80 no 17 pp 6747ndash6751 2008

[110] M Yamaguchi S Yoshikawa Y Tahara D Niwa Y Imai andV Shetty ldquoPoint-of-usemeasurement of salivary cortisol levelsrdquoin Proceedings of the IEEE Sensors (SENSORS rsquo09) pp 343ndash346Christchurch New Zealand October 2009

[111] M Yamaguchi Y Matsuda S Sasaki et al ldquoImmunosensorwith fluid control mechanism for salivary cortisol analysisrdquoBiosensors and Bioelectronics vol 41 no 1 pp 186ndash191 2013

[112] S K Arya G Chornokur M Venugopal and S BhansalildquoAntibody modified gold micro array electrode based electro-chemical immunosensor for ultrasensitive detection of cortisolin saliva and ISFrdquoProcedia Engineering vol 5 pp 804ndash807 2010

[113] C Tlili N V Myung V Shetty and A Mulchandani ldquoLabel-free chemiresistor immunosensor for stress biomarker cortisolin salivardquo Biosensors and Bioelectronics vol 26 no 11 pp 4382ndash4386 2011

[114] S K Arya S Saha J E Ramirez-Vick V Gupta S Bhansaliand S P Singh ldquoRecent advances in ZnO nanostructures andthin films for biosensor applications reviewrdquoAnalytica ChimicaActa vol 737 pp 1ndash21 2012

[115] P K Vabbina A Kaushik K Tracy S Bhansali and NPala ldquoZinc oxide nanostructures for electrochemical cortisolbiosensingrdquo in Smart Biomedical and Physiological Sensor Tech-nology XI vol 9107 of Proceedings of SPIE International Societyfor Optics and Photonics 2014

[116] P Brandtzaeg ldquoDo salivary antibodies reliably reflect bothmucosal and systemic immunityrdquo Annals of the New YorkAcademy of Sciences vol 1098 pp 288ndash311 2007

[117] M J Blaser G I Perez-Perez J Lindenbaum et al ldquoAssociationof infection due to Helicobacter pylori with specific uppergastrointestinal pathologyrdquo Reviews of Infectious Diseases vol13 supplement 8 pp S704ndashS708 1991

[118] T Matysiak-Budnik and F Megraud ldquoHelicobacter pyloriinfection and gastric cancerrdquo European Journal of Cancer vol42 no 6 pp 708ndash716 2006

[119] E Bayerdorffer A Neubauer B Rudolf et al ldquoRegressionof primary gastric lymphoma of mucosa-associated lymphoidtissue type after cure of Helicobacter pylori infectionrdquo TheLancet vol 345 no 8965 pp 1591ndash1594 1995

[120] C A Fallone M Elizov P Cleland et al ldquoDetection of Heli-cobacter pylori infection by saliva IgG testingrdquo The AmericanJournal of Gastroenterology vol 91 no 6 pp 1145ndash1149 1996

[121] F Luzza G Oderda M Maletta et al ldquoSalivary immunoglob-ulin G assay to diagnose Helicobacter pylori infection inchildrenrdquo Journal of Clinical Microbiology vol 35 no 12 pp3358ndash3360 1997

[122] F Luzza M Maletta M Imeneo et al ldquoSalivary-specificimmunoglobulin G in the diagnosis of Helicobacter pyloriinfection in dyspeptic patientsrdquo The American Journal of Gas-troenterology vol 90 no 10 pp 1820ndash1823 1995

[123] M V da Silva E D Camargo A J Vaz and L Batista ldquoImmun-odiagnosis of human leptospirosis using salivardquo Transactions ofthe Royal Society of Tropical Medicine and Hygiene vol 86 no5 pp 560ndash561 1992

[124] L de Cock V Hutse E Verhaegen S Quoilin H Vanden-berghe and R Vranckx ldquoDetection of HCV antibodies in oralfluidrdquo Journal of Virological Methods vol 122 no 2 pp 179ndash1832004

[125] K Fransen T Vermoesen G Beelaert et al ldquoUsing conven-tional HIV tests on oral fluidrdquo Journal of Virological Methodsvol 194 no 1-2 pp 46ndash51 2013

[126] V Gonzalez E Martro C Folch et al ldquoDetection of hepatitis Cvirus antibodies in oral fluid specimens for prevalence studiesrdquoEuropean Journal of Clinical Microbiology amp Infectious Diseasesvol 27 no 2 pp 121ndash126 2008

[127] S R Lee K W Kardos E Schiff et al ldquoEvaluation of a newrapid test for detecting HCV infection suitable for use withblood or oral fluidrdquo Journal of Virological Methods vol 172 no1-2 pp 27ndash31 2011

[128] D Lucidarme A Decoster D Fremaux et al ldquoRoutine practiceHCV infection screening with saliva samples multicentricstudy in an intravenous drug user populationrdquo Gastroenterolo-gie Clinique et Biologique vol 31 no 5 pp 480ndash484 2007

[129] M Moorthy H Daniel G Kurian and P Abraham ldquoAnevaluation of saliva as an alternative to plasma for the detectionof hepatitis C virus antibodiesrdquo Indian Journal of MedicalMicrobiology vol 26 no 4 pp 327ndash332 2008

[130] J F Zmuda B Wagoneer L Liotta and G Whiteley ldquoRecog-nition of multiple classes of hepatitis C antibodies increasesdetection sensitivity in oral fluidrdquo Clinical and DiagnosticLaboratory Immunology vol 8 no 6 pp 1267ndash1270 2001

[131] S Nandikonda Analysis of Salivary Immunoglobulin A Levelsand Its Correlation with Oral Candidiasis in Seropositive HIVPatients RajivGandhiUniversity ofHealth Sciences BangaloreIndia 2006

[132] S Jeganathan D Ufomata J A Hobkirk and L IvanyildquoImmunoglobulin A1 and A2 subclass of salivary antibodies toCandida albicans in patients with oral candidosisrdquo Clinical ampExperimental Immunology vol 70 no 2 pp 316ndash321 1987

[133] R Del Muro E Acosta E Merino W Glender and L Ortiz-Ortiz ldquoDiagnosis of intestinal amebiasis using salivary IgAantibody detectionrdquo Journal of Infectious Diseases vol 162 no6 pp 1360ndash1364 1990

[134] E M El Hamshary and W A S Arafa ldquoDetection of IgAanti-Entamoeba histolytica in the patientsrsquo salivardquo Journal of theEgyptian Society of Parasitology vol 34 no 3 pp 1095ndash11042004

[135] C S Needham J E Lillywhite N M R Beasley J M DidierC M Kihamia and D A P Bundy ldquoPotential for diagnosis ofintestinal nematode infections through antibody detection insalivardquoTransactions of the Royal Society of TropicalMedicine andHygiene vol 90 no 5 pp 526ndash530 1996

[136] A Stroehle K Schmidt I Heinzer A Naguleswaran and AHemphill ldquoPerformance of a western immunoblot assay todetect specific anti-Toxoplasma gondii IgG antibodies in humansalivardquo Journal of Parasitology vol 91 no 3 pp 561ndash563 2005

[137] E Acosta ldquoAntibodies to the metacestode of Taenia soliumin the saliva from patients with neurocysticercosisrdquo Journal ofClinical Laboratory Analysis vol 4 no 2 pp 90ndash94 1990

[138] I Tajima O Asami and E Sugiura ldquoMonitor of antibodiesin human saliva using a piezoelectric quartz crystal biosensorrdquoAnalytica Chimica Acta vol 365 no 1ndash3 pp 147ndash149 1998

[139] A Ahmed J V Rushworth J D Wright and P A Mill-ner ldquoNovel impedimetric immunosensor for detection ofpathogenic bacteria Streptococcus pyogenes in human salivardquoAnalytical Chemistry vol 85 no 24 pp 12118ndash12125 2013

[140] J Y Gerasimov and R Y Lai ldquoDesign and characterization ofan electrochemical peptide-based sensor fabricated via ldquoclickrdquochemistryrdquoChemical Communications vol 47 no 30 pp 8688ndash8690 2011


[141] A Vallee-Belisle F Ricci T Uzawa F Xia and K W PlaxcoldquoBioelectrochemical switches for the quantitative detection ofantibodies directly in whole bloodrdquo Journal of the AmericanChemical Society vol 134 no 37 pp 15197ndash15200 2012

[142] A McQuistan A J Zaitouna E Echeverria and R Y LaildquoUse of thiolated oligonucleotides as anti-fouling diluents inelectrochemical peptide-based sensorsrdquo Chemical Communica-tions vol 50 no 36 pp 4690ndash4692 2014

[143] M A R St John Y Li X Zhou et al ldquoInterleukin 6 andinterleukin 8 as potential biomarkers for oral cavity and oropha-ryngeal squamous cell carcinomardquo Archives of OtolaryngologyHead and Neck Surgery vol 130 no 8 pp 929ndash935 2004

[144] W Tan L Sabet Y Li et al ldquoOptical protein sensor for detectingcancer markers in salivardquo Biosensors and Bioelectronics vol 24no 2 pp 266ndash271 2008

[145] D T Wong ldquoTowards a simple saliva-based test for thedetection of oral cancer ldquoOral fluid (saliva) which is the mirrorof the body is a perfect medium to be explored for health anddisease surveillancerdquordquo Expert Review of Molecular Diagnosticsvol 6 no 3 pp 267ndash272 2006

[146] Y J Jou C D Lin C H Lai et al ldquoProteomic identificationof salivary transferrin as a biomarker for early detection of oralcancerrdquoAnalyticaChimicaActa vol 681 no 1-2 pp 41ndash48 2010

[147] E J Franzmann E P Reategui F Pedroso et al ldquoSoluble CD44is a potential marker for the early detection of head and neckcancerrdquo Cancer Epidemiology Biomarkers and Prevention vol16 no 7 pp 1348ndash1355 2007

[148] R Nagler G Bahar T Shpitzer and R Feinmesser ldquoConcomi-tant analysis of salivary tumor markersmdasha new diagnostic toolfor oral cancerrdquo Clinical Cancer Research vol 12 no 13 pp3979ndash3984 2006

[149] L-P Zhong C-P Zhang J-W Zheng J Li W-T Chen andZ-Y Zhang ldquoIncreased Cyfra 21-1 concentration in saliva fromprimary oral squamous cell carcinoma patientsrdquo Archives ofOral Biology vol 52 no 11 pp 1079ndash1087 2007

[150] Y-J Jou C-D Lin C-H Lai et al ldquoSalivary zinc finger protein510 peptide as a novel biomarker for detection of oral squamouscell carcinoma in early stagesrdquoClinicaChimicaActa vol 412 no15-16 pp 1357ndash1365 2011

[151] L Zhang J J Farrell H Zhou et al ldquoSalivary transcriptomicbiomarkers for detection of resectable pancreatic cancerrdquo Gas-troenterology vol 138 no 3 pp 949ndash957 2010

[152] D T Wong L Zhang H Xiao and H Zhou ldquoSalivarybiomarkers for lung cancer detectionrdquo in WIPO Patentscope2011

[153] L Zhang H Xiao H Zhou et al ldquoDevelopment of tran-scriptomic biomarker signature in human saliva to detect lungcancerrdquo Cellular and Molecular Life Sciences vol 69 no 19 pp3341ndash3350 2012

[154] L R Bigler C F Streckfus L Copeland et al ldquoThe potential useof saliva to detect recurrence of disease in women with breastcarcinomardquo Journal of Oral Pathology and Medicine vol 31 no7 pp 421ndash431 2002

[155] C Streckfus L Bigler T Dellinger X Dai A Kingman and J TThigpen ldquoThe presence of soluble c-erbB-2 in saliva and serumamong women with breast carcinoma a preliminary studyrdquoClinical Cancer Research vol 6 no 6 pp 2363ndash2370 2000

[156] C Streckfus L Bigler M Tucci and J T Thigpen ldquoA pre-liminary study of CA15-3 c-erbB-2 epidermal growth factorreceptor cathepsin-D and p53 in saliva among women withbreast carcinomardquo Cancer Investigation vol 18 no 2 pp 101ndash109 2000

[157] M N Brooks J Wang Y Li R Zhang D Elashoff and D TWong ldquoSalivary protein factors are elevated in breast cancerpatientsrdquoMolecular Medicine Reports vol 1 no 3 pp 375ndash3782008

[158] Y-H Liang C-C Chang C-C Chen Y Chu-Su and C-WLin ldquoDevelopment of an AuZnO thin film surface plasmonresonance-based biosensor immunoassay for the detection ofcarbohydrate antigen 15-3 in human salivardquo Clinical Biochem-istry vol 45 no 18 pp 1689ndash1693 2012

[159] J Chen J Lin X Zhang et al ldquoLabel-free fluorescent biosensorbased on the target recycling andThioflavin T-induced quadru-plex formation for short DNA species of c-erbB-2 detectionrdquoAnalytica Chimica Acta vol 817 pp 42ndash47 2014

[160] F Wei P Patel W Liao et al ldquoElectrochemical sensor formultiplex biomarkers detectionrdquo Clinical Cancer Research vol15 no 13 pp 4446ndash4452 2009

[161] J V Jokerst A Raamanathan N Christodoulides et al ldquoNano-bio-chips for high performance multiplexed protein detectiondeterminations of cancer biomarkers in serum and saliva usingquantum dot bioconjugate labelsrdquo Biosensors and Bioelectronicsvol 24 no 12 pp 3622ndash3629 2009

[162] S NieWHHenley S EMiller et al ldquoAn automated integratedplatform for rapid and sensitive multiplexed protein profilingusing human saliva samplesrdquo Lab on a Chip vol 14 no 6 pp1087ndash1098 2014

[163] S Sadhasivam J C Chen S Savitha CWChang and FH LinldquoApplication of carbon nanotubes layered on silicon wafer forthe detection of breast cancer marker carbohydrate antigen 15-3 by immuno-polymerase chain reactionrdquo Journal of MaterialsScience Materials in Medicine vol 25 no 1 pp 101ndash111 2014

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Anatomy Research International

PeptidesInternational Journal of


Hindawi Publishing Corporation httpwwwhindawicom

International Journal of

Volume 2014

Zoology


Molecular Biology International

GenomicsInternational Journal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014


BioinformaticsAdvances in

Marine BiologyJournal of



Signal TransductionJournal of


BioMed Research International

Evolutionary BiologyInternational Journal of



Biochemistry Research International

ArchaeaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014


Genetics Research International


Advances in

Virolog y

Hindawi Publishing Corporationhttpwwwhindawicom

Nucleic AcidsJournal of

Volume 2014

Stem CellsInternational



Enzyme Research



Microbiology


diseases (ii) supporting treatment decision making and (iii)monitoring disease progression andor treatment outcomesThese biomarkers have been previously studied by employingconventional collection and laboratory-based assay methodsAlthough saliva sampling using oral fluid collectors andcommercial devices is generally safe and convenient touse and provides sufficient homogeneous sample with lowviscosity it still presents several shortcomings such as (i)the requirement of supervision (ii) the need to follow theprocedures carefully to ensure sample adequacy and (iii)the relatively time-consuming process (sim1-2min) [7] On theother hand salivary analysis using laboratory-based assaymethods often requires relatively large volumes of sampleand involves multiple steps of sample acquisition labellingfreezing transportation processing in the laboratory (egcentrifugation sorting aliquoting and loading into theanalyser) analysis and finally results reporting It is atedious and lengthy process in which each step needs tobe performed carefully as it is fraught with several potentialquality failure points In such scenarios saliva sample storageprocedures between sampling and analysis also need to betaken into account as it may affect the relative stability ofthe salivary components In terms of financial implicationsthe analytical instruments utilised are expensive hence avail-able in centralised laboratories only There are also costsassociated with the testing supplies sample acquisition andtransport supplies as well as the labour costs incurred acrossthe total process The aforementioned drawbacks have led tothe demand for rapid and reliable quantification of salivarybiomarkers through the use of biosensing technology [8]Theability to immediately collect and analyse salivary biomarkerson site (point-of-care (POC)) provides countless advantagesfor clinical applications

Biosensors are small self-contained analytical devicesused for the detection and measurement of a particularsubstance (analyte) of interest A biological sensing element(eg enzymes antibodies nucleic acids etc) is placed inintimate contact with a transducer (eg optical electro-chemical piezoelectric etc) transforming the biorecognitionevent into a more simple and quantifiable signal Generallythe strength of the output signal is proportional to theconcentration of the analyte of interest Finally the resultis processed using associated electronics and embeddedsoftware systems which provide simple digital feedbackdisplayed using a reader device in a user-friendly mannerfor interpretation by nonexperts [5] However it is note-worthy that the reader device accounts for the most expen-sive part of the sensor so it is normally incorporated insensors that are intended for commercial purposes For acomprehensive description of the progress in biosensors formedical applications with specific emphasis in noninvasivemeasurement the following book chapter is recommended[9]

This paper reviews the significance of salivary biomarkersfor clinical diagnosis and therapeutic applications Eachbiomarker and its associated detection methods presentdifferent particularities drawbacks and challenges Hencethe most common salivary biomarkers and their biosensingmechanisms have been described separately focusing on

the reported technologies used for both the collection and thescreening of these biomarkers

2 Salivary Glucose

As glucose is a small organic molecule it has the abilityto move easily through the blood vessels membranes dif-fusing from the blood plasma to the gingival fluid via thegingival sulcus into saliva There are many controversialfindings regarding the correlation between capillary bloodglucose (CBG) and salivary glucose (SG) concentrationsin the literature In healthy subjects there is a lack ofrelationship between CBG and SG concentrations becauseinsulin from beta cells in the pancreas is released into thebloodstream to normalise the CBG level when the glucoseconcentration exceeds a certain limit [4 10] In diabetics SGconcentration is significantly higher than in healthy subjects[4 11ndash17] However the association between CBG and SGlevels among diabetics is ambiguously established as thereare contradicting studies that found both positive correlation[4 11 12 16] and absence of [14 17] correlation hencemakingthe use of SG concentration as an index for diabetes mellitusinconclusive

Gingival crevicular fluid (GCF) is an extracellular fluidsecreted from the epithelia of the gingival crevice a V shapedcrevice surrounding all teeth which is located between thetooth and the gingiva with a clinically normal depth of05 to 20mm [18 19] In the last decade researchers haveinvestigated the possibility of using gingival crevicular blood(GCB) as an assessmentmethod tomeasure glycaemia amongdiabetics The results revealed that there is a significantcorrelation between GCB glucose and CBG concentrations[20ndash28] During periodontal inflammation with or withoutthe complicating factor of diabetes an ample amount ofextravasated blood is produced [29] Since periodontal dis-ease is prevalent among diabetics the GCB collected with theprobing technique during a general periodontal examinationcan be used to diagnose diabetes or to monitor CBG levelin known diabetics This technique is inexpensive safe andeasy to performwithout the use of additional tools such as thesharp lancet for finger puncture Hence GCB concentrationis suitable for noninvasive CBG assessment especially inperiodontal management among diabetics [20ndash28]

The first glucose biosensor was developed by Clark andLyons [30] The biosensor consisted of an electrode thatmonitored the consumption of oxygen (O

2) catalysed by

glucose oxidase (GOx) enzyme as shown in

Glucose +O2

GOx997888997888997888rarr Gluconic acid

+Hydrogen peroxide (H2O2)

(1)

In order to determine SG concentration Yamaguchi et al[31] developed a system that combined flow injection anal-ysis and an O

2electrode The O

2consumed was detected

amperometrically and as the reaction progressed a decreasein the output current was observed due to the reduction inthe concentration of dissolved O

2that reached the sensor

(see (1)) A constant current proportional to the glucose










2O2



2 The H




2levels




H2O2+ TMBZ


(2)




3 Salivary Lactate






Laser head

Lens

Photodiode

GC

F gl

ucos

e (m

mol

L)

Calibration curve 1


CB

G (m

mol

l)

Calibration curve 2

GCF glucose (mmolL)

Start

50mgdL


GCF glucose monitor




2and producing H

2O2

Lactate +O2


2O2

(3)







(a) (b) (c)

Pores

Referenceelectrode

Counterelectrode

Sealing foil





2O2reacted












2O2(see (4))



+H2O2


(4)










2O2at 065V
























6 Salivary Hormones





Table1Summaryof

thea

nalytic

alparametersfor

catalytic


theliterature

Biom

arker

Biorecognitio

nTransducer

Samplev

olum

e(120583L)

Working

range

Sensitivity

Detectio

nlim

it(D

L)Re

ference

Glucose

GOx

Electro

chem

ical

200

01ndash10mgd

Lminus1

mdashmdash

[31]

GOx

Electro

chem

ical

5001ndash10mgd

Lminus1

mdashmdash

[32]

GOxFclowast

Electro

chem

ical

mdash0ndash

22m

M2145n


1120583M

[33]

GOxPO

xTM

BZlowast

Optical

02

0ndash10mgd

Lminus1

mdashmdash

[3435]

GOxPO

xTM

BZlowast

Optical

02

mdashmdash

mdash[19

]

Lactate

LOx

Electro

chem

ical

1000

mdash42

nAmMminus1

mdash[442]

LOx

Electro

chem

ical

mdash001ndash5

mM

78nA

mMminus1

mdash[38]

LOxluminollowast

Electro

chem

iluminescent

5001ndash05m

Mmdash

5120583M

[36]

LOxPBlowast

Electro

chem

ical

mdash01ndash10

mM

0553120583

AmMminus1

50120583M

[44]

LOxPBlowast

Electro

chem

ical

401ndash5m


300120583

M[45]

Phosph

ate

PyOx

Electro

chem

ical

5075

ndash625120583M

52389

nAmMminus1

36120583

M[53]

Alpha-amylase

GDG

Ox

Electro

chem

ical

100

0ndash30

UmLminus

1mdash

mdash[62]

GDM

RGOx

Electro

chem

ical

3501ndash3m

Mmdash

5012

nM(530m

in)

[63]

Gal-G

2-CN

POptical

50ndash

200U

mLminus

1mdash

mdash[66]

Gal-G

2-CN

POptical

3010ndash140

UmLminus

1mdash

mdash[65]

Gal-G

2-CN

POptical

2510ndash230

UmLminus

1mdash

mdash[64]

MPGOxPO

xElectro

chem

ical

500ndash

190U

mLminus

1mdash

mdash[67]

AmylaseA

g-Ablowast

Immun

oelectrochem

ical


mLminus

1mdash

157p

gmLminus1

[68]

GDG

OxFclowast

Electro

chem

ical

mdash60ndash8

40UmLminus

1mdash

17UmLminus1

[70]

GDM

RGOxPBlowast

Electro

chem

ical

mdash5ndash250U

mLminus

114nA

Uminus1

5UmLminus1

[71]

lowastTh

ebiorecognitio


with

thechromogen

that

provides

thechange

ofcolour

foro

pticaldeterm

inations

with

theredo

xmediators

that

facilitateele

ctrons

transfe

rfor

electrochem

ical

determ

inations








































9 Conclusion



Table2Summaryof

ther

eportedSL

immun


Biom

arker

Biorecognitio

nTransducer

Samplev

olum

e(120583L)

Working

range

Sensitivity

Detectio

nlim

it(D

L)Re

ference

Cortisol

CortisolAg-Ab

AP

Immun

oelectrochem

ical

30mdash

mdash021ng

mLminus1

[108]


Optical

mdash15

ndash10n

gmLminus

1mdash

10ng

mLminus1

[109]

Cortisol-link

erconjugate-Ab

Optical

5091ndash934

pgmLminus1

162R

UmLngminus1

49pg

mLminus1

[74]

GOx-cortiso

lcon

jugateA

g-Ab

Optical

100

1ndash10ng

mLminus

1mdash

mdash[110]

GOx-cortiso

lcon

jugateA

g-Ab

Immun

oelectrochem

ical

4001ndash10ng

mLminus

1mdash

mdash[111]

CortisolAg-Ab

Immun

oelectrochem

ical

mdash1p

Mminus1 120583

M1165

kΩMminus1

1pM

[112]


ortisolAb


iresistors

mdash0001ndash10ng

mLminus

11397n

gmLminus1

1pgm

Lminus1

[113]

Cortisol

conjugate-BS

AA

nti-c

ortisolAb

Immun

oelectrochem

ical

10100p

Mto

100n

M540Ω

Mminus1

1pM

[115]

Testo

sterone

Testo

sterone-link

erconjugate-Ag-Ab

Optical

mdash25ndash250

pgmLminus

145

RUmLngminus1

154pg

mLminus1

[87]

Immun

oglobu

linA(Ig

A)

IgA-

antiIgA

Piezoelectric

1000

0mdash

mdashmdash

[138]

SAG1antigen

mdashmdash

mdashmdash

mdash[162]

IgGHIV

target

Electro

chem

ical

mdashmdash

mdash1n

M[14

2]Streptococcus

pyogenes(S

pyogenes)b

acteria

Anti-S

pyogenes

Ab-Ptyr-biotin-N

eutrAv

idin

Immun

oelectrochem

ical

mdash100to

105cells

per10120583

Lmdash

mdash[139]

Interle

ukin-8

(IL-8)

IL-8

capturep

robe-IL-8

targetFluorescent

Optical

506fMndash12p

Mmdash

40fM

[144]

IL-8

capturep

robe-IL-8

targetFluorescent

Optical

20mdash

mdash08p

M[159]

Cancer

antig

ens

15-3

(CA15-3)

Anti-C

A15-3

AbOptical


1mdash

mdash[158]

Anti-C

A153Ab

Optical


10001ndash001Um

L0001U

mL

[163]

IL-8

mRN

Aandproteinprob

eElectro

chem

ical

mdash5fMndash50p

M

10ndash12500

pgm

L39fM

74pgm

Lmdash

[160]








Acknowledgments


References


















































































































































































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology










2O2



2 The H




2levels




H2O2+ TMBZ


(2)




3 Salivary Lactate






Laser head

Lens

Photodiode

GC

F gl

ucos

e (m

mol

L)

Calibration curve 1


CB

G (m

mol

l)

Calibration curve 2

GCF glucose (mmolL)

Start

50mgdL


GCF glucose monitor




2and producing H

2O2

Lactate +O2


2O2

(3)







(a) (b) (c)

Pores

Referenceelectrode

Counterelectrode

Sealing foil





2O2reacted












2O2(see (4))



+H2O2


(4)










2O2at 065V
























6 Salivary Hormones





Table1Summaryof

thea

nalytic

alparametersfor

catalytic


theliterature

Biom

arker

Biorecognitio

nTransducer

Samplev

olum

e(120583L)

Working

range

Sensitivity

Detectio

nlim

it(D

L)Re

ference

Glucose

GOx

Electro

chem

ical

200

01ndash10mgd

Lminus1

mdashmdash

[31]

GOx

Electro

chem

ical

5001ndash10mgd

Lminus1

mdashmdash

[32]

GOxFclowast

Electro

chem

ical

mdash0ndash

22m

M2145n


1120583M

[33]

GOxPO

xTM

BZlowast

Optical

02

0ndash10mgd

Lminus1

mdashmdash

[3435]

GOxPO

xTM

BZlowast

Optical

02

mdashmdash

mdash[19

]

Lactate

LOx

Electro

chem

ical

1000

mdash42

nAmMminus1

mdash[442]

LOx

Electro

chem

ical

mdash001ndash5

mM

78nA

mMminus1

mdash[38]

LOxluminollowast

Electro

chem

iluminescent

5001ndash05m

Mmdash

5120583M

[36]

LOxPBlowast

Electro

chem

ical

mdash01ndash10

mM

0553120583

AmMminus1

50120583M

[44]

LOxPBlowast

Electro

chem

ical

401ndash5m


300120583

M[45]

Phosph

ate

PyOx

Electro

chem

ical

5075

ndash625120583M

52389

nAmMminus1

36120583

M[53]

Alpha-amylase

GDG

Ox

Electro

chem

ical

100

0ndash30

UmLminus

1mdash

mdash[62]

GDM

RGOx

Electro

chem

ical

3501ndash3m

Mmdash

5012

nM(530m

in)

[63]

Gal-G

2-CN

POptical

50ndash

200U

mLminus

1mdash

mdash[66]

Gal-G

2-CN

POptical

3010ndash140

UmLminus

1mdash

mdash[65]

Gal-G

2-CN

POptical

2510ndash230

UmLminus

1mdash

mdash[64]

MPGOxPO

xElectro

chem

ical

500ndash

190U

mLminus

1mdash

mdash[67]

AmylaseA

g-Ablowast

Immun

oelectrochem

ical


mLminus

1mdash

157p

gmLminus1

[68]

GDG

OxFclowast

Electro

chem

ical

mdash60ndash8

40UmLminus

1mdash

17UmLminus1

[70]

GDM

RGOxPBlowast

Electro

chem

ical

mdash5ndash250U

mLminus

114nA

Uminus1

5UmLminus1

[71]

lowastTh

ebiorecognitio


with

thechromogen

that

provides

thechange

ofcolour

foro

pticaldeterm

inations

with

theredo

xmediators

that

facilitateele

ctrons

transfe

rfor

electrochem

ical

determ

inations








































9 Conclusion



Table2Summaryof

ther

eportedSL

immun


Biom

arker

Biorecognitio

nTransducer

Samplev

olum

e(120583L)

Working

range

Sensitivity

Detectio

nlim

it(D

L)Re

ference

Cortisol

CortisolAg-Ab

AP

Immun

oelectrochem

ical

30mdash

mdash021ng

mLminus1

[108]


Optical

mdash15

ndash10n

gmLminus

1mdash

10ng

mLminus1

[109]

Cortisol-link

erconjugate-Ab

Optical

5091ndash934

pgmLminus1

162R

UmLngminus1

49pg

mLminus1

[74]

GOx-cortiso

lcon

jugateA

g-Ab

Optical

100

1ndash10ng

mLminus

1mdash

mdash[110]

GOx-cortiso

lcon

jugateA

g-Ab

Immun

oelectrochem

ical

4001ndash10ng

mLminus

1mdash

mdash[111]

CortisolAg-Ab

Immun

oelectrochem

ical

mdash1p

Mminus1 120583

M1165

kΩMminus1

1pM

[112]


ortisolAb


iresistors

mdash0001ndash10ng

mLminus

11397n

gmLminus1

1pgm

Lminus1

[113]

Cortisol

conjugate-BS

AA

nti-c

ortisolAb

Immun

oelectrochem

ical

10100p

Mto

100n

M540Ω

Mminus1

1pM

[115]

Testo

sterone

Testo

sterone-link

erconjugate-Ag-Ab

Optical

mdash25ndash250

pgmLminus

145

RUmLngminus1

154pg

mLminus1

[87]

Immun

oglobu

linA(Ig

A)

IgA-

antiIgA

Piezoelectric

1000

0mdash

mdashmdash

[138]

SAG1antigen

mdashmdash

mdashmdash

mdash[162]

IgGHIV

target

Electro

chem

ical

mdashmdash

mdash1n

M[14

2]Streptococcus

pyogenes(S

pyogenes)b

acteria

Anti-S

pyogenes

Ab-Ptyr-biotin-N

eutrAv

idin

Immun

oelectrochem

ical

mdash100to

105cells

per10120583

Lmdash

mdash[139]

Interle

ukin-8

(IL-8)

IL-8

capturep

robe-IL-8

targetFluorescent

Optical

506fMndash12p

Mmdash

40fM

[144]

IL-8

capturep

robe-IL-8

targetFluorescent

Optical

20mdash

mdash08p

M[159]

Cancer

antig

ens

15-3

(CA15-3)

Anti-C

A15-3

AbOptical


1mdash

mdash[158]

Anti-C

A153Ab

Optical


10001ndash001Um

L0001U

mL

[163]

IL-8

mRN

Aandproteinprob

eElectro

chem

ical

mdash5fMndash50p

M

10ndash12500

pgm

L39fM

74pgm

Lmdash

[160]








Acknowledgments


References


















































































































































































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology





Laser head

Lens

Photodiode

GC

F gl

ucos

e (m

mol

L)

Calibration curve 1


CB

G (m

mol

l)

Calibration curve 2

GCF glucose (mmolL)

Start

50mgdL


GCF glucose monitor




2and producing H

2O2

Lactate +O2


2O2

(3)







(a) (b) (c)

Pores

Referenceelectrode

Counterelectrode

Sealing foil





2O2reacted












2O2(see (4))



+H2O2


(4)










2O2at 065V
























6 Salivary Hormones





Table1Summaryof

thea

nalytic

alparametersfor

catalytic


theliterature

Biom

arker

Biorecognitio

nTransducer

Samplev

olum

e(120583L)

Working

range

Sensitivity

Detectio

nlim

it(D

L)Re

ference

Glucose

GOx

Electro

chem

ical

200

01ndash10mgd

Lminus1

mdashmdash

[31]

GOx

Electro

chem

ical

5001ndash10mgd

Lminus1

mdashmdash

[32]

GOxFclowast

Electro

chem

ical

mdash0ndash

22m

M2145n


1120583M

[33]

GOxPO

xTM

BZlowast

Optical

02

0ndash10mgd

Lminus1

mdashmdash

[3435]

GOxPO

xTM

BZlowast

Optical

02

mdashmdash

mdash[19

]

Lactate

LOx

Electro

chem

ical

1000

mdash42

nAmMminus1

mdash[442]

LOx

Electro

chem

ical

mdash001ndash5

mM

78nA

mMminus1

mdash[38]

LOxluminollowast

Electro

chem

iluminescent

5001ndash05m

Mmdash

5120583M

[36]

LOxPBlowast

Electro

chem

ical

mdash01ndash10

mM

0553120583

AmMminus1

50120583M

[44]

LOxPBlowast

Electro

chem

ical

401ndash5m


300120583

M[45]

Phosph

ate

PyOx

Electro

chem

ical

5075

ndash625120583M

52389

nAmMminus1

36120583

M[53]

Alpha-amylase

GDG

Ox

Electro

chem

ical

100

0ndash30

UmLminus

1mdash

mdash[62]

GDM

RGOx

Electro

chem

ical

3501ndash3m

Mmdash

5012

nM(530m

in)

[63]

Gal-G

2-CN

POptical

50ndash

200U

mLminus

1mdash

mdash[66]

Gal-G

2-CN

POptical

3010ndash140

UmLminus

1mdash

mdash[65]

Gal-G

2-CN

POptical

2510ndash230

UmLminus

1mdash

mdash[64]

MPGOxPO

xElectro

chem

ical

500ndash

190U

mLminus

1mdash

mdash[67]

AmylaseA

g-Ablowast

Immun

oelectrochem

ical


mLminus

1mdash

157p

gmLminus1

[68]

GDG

OxFclowast

Electro

chem

ical

mdash60ndash8

40UmLminus

1mdash

17UmLminus1

[70]

GDM

RGOxPBlowast

Electro

chem

ical

mdash5ndash250U

mLminus

114nA

Uminus1

5UmLminus1

[71]

lowastTh

ebiorecognitio


with

thechromogen

that

provides

thechange

ofcolour

foro

pticaldeterm

inations

with

theredo

xmediators

that

facilitateele

ctrons

transfe

rfor

electrochem

ical

determ

inations








































9 Conclusion



Table2Summaryof

ther

eportedSL

immun


Biom

arker

Biorecognitio

nTransducer

Samplev

olum

e(120583L)

Working

range

Sensitivity

Detectio

nlim

it(D

L)Re

ference

Cortisol

CortisolAg-Ab

AP

Immun

oelectrochem

ical

30mdash

mdash021ng

mLminus1

[108]


Optical

mdash15

ndash10n

gmLminus

1mdash

10ng

mLminus1

[109]

Cortisol-link

erconjugate-Ab

Optical

5091ndash934

pgmLminus1

162R

UmLngminus1

49pg

mLminus1

[74]

GOx-cortiso

lcon

jugateA

g-Ab

Optical

100

1ndash10ng

mLminus

1mdash

mdash[110]

GOx-cortiso

lcon

jugateA

g-Ab

Immun

oelectrochem

ical

4001ndash10ng

mLminus

1mdash

mdash[111]

CortisolAg-Ab

Immun

oelectrochem

ical

mdash1p

Mminus1 120583

M1165

kΩMminus1

1pM

[112]


ortisolAb


iresistors

mdash0001ndash10ng

mLminus

11397n

gmLminus1

1pgm

Lminus1

[113]

Cortisol

conjugate-BS

AA

nti-c

ortisolAb

Immun

oelectrochem

ical

10100p

Mto

100n

M540Ω

Mminus1

1pM

[115]

Testo

sterone

Testo

sterone-link

erconjugate-Ag-Ab

Optical

mdash25ndash250

pgmLminus

145

RUmLngminus1

154pg

mLminus1

[87]

Immun

oglobu

linA(Ig

A)

IgA-

antiIgA

Piezoelectric

1000

0mdash

mdashmdash

[138]

SAG1antigen

mdashmdash

mdashmdash

mdash[162]

IgGHIV

target

Electro

chem

ical

mdashmdash

mdash1n

M[14

2]Streptococcus

pyogenes(S

pyogenes)b

acteria

Anti-S

pyogenes

Ab-Ptyr-biotin-N

eutrAv

idin

Immun

oelectrochem

ical

mdash100to

105cells

per10120583

Lmdash

mdash[139]

Interle

ukin-8

(IL-8)

IL-8

capturep

robe-IL-8

targetFluorescent

Optical

506fMndash12p

Mmdash

40fM

[144]

IL-8

capturep

robe-IL-8

targetFluorescent

Optical

20mdash

mdash08p

M[159]

Cancer

antig

ens

15-3

(CA15-3)

Anti-C

A15-3

AbOptical


1mdash

mdash[158]

Anti-C

A153Ab

Optical


10001ndash001Um

L0001U

mL

[163]

IL-8

mRN

Aandproteinprob

eElectro

chem

ical

mdash5fMndash50p

M

10ndash12500

pgm

L39fM

74pgm

Lmdash

[160]








Acknowledgments


References


















































































































































































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology


(a) (b) (c)

Pores

Referenceelectrode

Counterelectrode

Sealing foil





2O2reacted












2O2(see (4))



+H2O2


(4)










2O2at 065V
























6 Salivary Hormones





Table1Summaryof

thea

nalytic

alparametersfor

catalytic


theliterature

Biom

arker

Biorecognitio

nTransducer

Samplev

olum

e(120583L)

Working

range

Sensitivity

Detectio

nlim

it(D

L)Re

ference

Glucose

GOx

Electro

chem

ical

200

01ndash10mgd

Lminus1

mdashmdash

[31]

GOx

Electro

chem

ical

5001ndash10mgd

Lminus1

mdashmdash

[32]

GOxFclowast

Electro

chem

ical

mdash0ndash

22m

M2145n


1120583M

[33]

GOxPO

xTM

BZlowast

Optical

02

0ndash10mgd

Lminus1

mdashmdash

[3435]

GOxPO

xTM

BZlowast

Optical

02

mdashmdash

mdash[19

]

Lactate

LOx

Electro

chem

ical

1000

mdash42

nAmMminus1

mdash[442]

LOx

Electro

chem

ical

mdash001ndash5

mM

78nA

mMminus1

mdash[38]

LOxluminollowast

Electro

chem

iluminescent

5001ndash05m

Mmdash

5120583M

[36]

LOxPBlowast

Electro

chem

ical

mdash01ndash10

mM

0553120583

AmMminus1

50120583M

[44]

LOxPBlowast

Electro

chem

ical

401ndash5m


300120583

M[45]

Phosph

ate

PyOx

Electro

chem

ical

5075

ndash625120583M

52389

nAmMminus1

36120583

M[53]

Alpha-amylase

GDG

Ox

Electro

chem

ical

100

0ndash30

UmLminus

1mdash

mdash[62]

GDM

RGOx

Electro

chem

ical

3501ndash3m

Mmdash

5012

nM(530m

in)

[63]

Gal-G

2-CN

POptical

50ndash

200U

mLminus

1mdash

mdash[66]

Gal-G

2-CN

POptical

3010ndash140

UmLminus

1mdash

mdash[65]

Gal-G

2-CN

POptical

2510ndash230

UmLminus

1mdash

mdash[64]

MPGOxPO

xElectro

chem

ical

500ndash

190U

mLminus

1mdash

mdash[67]

AmylaseA

g-Ablowast

Immun

oelectrochem

ical


mLminus

1mdash

157p

gmLminus1

[68]

GDG

OxFclowast

Electro

chem

ical

mdash60ndash8

40UmLminus

1mdash

17UmLminus1

[70]

GDM

RGOxPBlowast

Electro

chem

ical

mdash5ndash250U

mLminus

114nA

Uminus1

5UmLminus1

[71]

lowastTh

ebiorecognitio


with

thechromogen

that

provides

thechange

ofcolour

foro

pticaldeterm

inations

with

theredo

xmediators

that

facilitateele

ctrons

transfe

rfor

electrochem

ical

determ

inations








































9 Conclusion



Table2Summaryof

ther

eportedSL

immun


Biom

arker

Biorecognitio

nTransducer

Samplev

olum

e(120583L)

Working

range

Sensitivity

Detectio

nlim

it(D

L)Re

ference

Cortisol

CortisolAg-Ab

AP

Immun

oelectrochem

ical

30mdash

mdash021ng

mLminus1

[108]


Optical

mdash15

ndash10n

gmLminus

1mdash

10ng

mLminus1

[109]

Cortisol-link

erconjugate-Ab

Optical

5091ndash934

pgmLminus1

162R

UmLngminus1

49pg

mLminus1

[74]

GOx-cortiso

lcon

jugateA

g-Ab

Optical

100

1ndash10ng

mLminus

1mdash

mdash[110]

GOx-cortiso

lcon

jugateA

g-Ab

Immun

oelectrochem

ical

4001ndash10ng

mLminus

1mdash

mdash[111]

CortisolAg-Ab

Immun

oelectrochem

ical

mdash1p

Mminus1 120583

M1165

kΩMminus1

1pM

[112]


ortisolAb


iresistors

mdash0001ndash10ng

mLminus

11397n

gmLminus1

1pgm

Lminus1

[113]

Cortisol

conjugate-BS

AA

nti-c

ortisolAb

Immun

oelectrochem

ical

10100p

Mto

100n

M540Ω

Mminus1

1pM

[115]

Testo

sterone

Testo

sterone-link

erconjugate-Ag-Ab

Optical

mdash25ndash250

pgmLminus

145

RUmLngminus1

154pg

mLminus1

[87]

Immun

oglobu

linA(Ig

A)

IgA-

antiIgA

Piezoelectric

1000

0mdash

mdashmdash

[138]

SAG1antigen

mdashmdash

mdashmdash

mdash[162]

IgGHIV

target

Electro

chem

ical

mdashmdash

mdash1n

M[14

2]Streptococcus

pyogenes(S

pyogenes)b

acteria

Anti-S

pyogenes

Ab-Ptyr-biotin-N

eutrAv

idin

Immun

oelectrochem

ical

mdash100to

105cells

per10120583

Lmdash

mdash[139]

Interle

ukin-8

(IL-8)

IL-8

capturep

robe-IL-8

targetFluorescent

Optical

506fMndash12p

Mmdash

40fM

[144]

IL-8

capturep

robe-IL-8

targetFluorescent

Optical

20mdash

mdash08p

M[159]

Cancer

antig

ens

15-3

(CA15-3)

Anti-C

A15-3

AbOptical


1mdash

mdash[158]

Anti-C

A153Ab

Optical


10001ndash001Um

L0001U

mL

[163]

IL-8

mRN

Aandproteinprob

eElectro

chem

ical

mdash5fMndash50p

M

10ndash12500

pgm

L39fM

74pgm

Lmdash

[160]








Acknowledgments


References


















































































































































































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology




2O2(see (4))



+H2O2


(4)










2O2at 065V
























6 Salivary Hormones





Table1Summaryof

thea

nalytic

alparametersfor

catalytic


theliterature

Biom

arker

Biorecognitio

nTransducer

Samplev

olum

e(120583L)

Working

range

Sensitivity

Detectio

nlim

it(D

L)Re

ference

Glucose

GOx

Electro

chem

ical

200

01ndash10mgd

Lminus1

mdashmdash

[31]

GOx

Electro

chem

ical

5001ndash10mgd

Lminus1

mdashmdash

[32]

GOxFclowast

Electro

chem

ical

mdash0ndash

22m

M2145n


1120583M

[33]

GOxPO

xTM

BZlowast

Optical

02

0ndash10mgd

Lminus1

mdashmdash

[3435]

GOxPO

xTM

BZlowast

Optical

02

mdashmdash

mdash[19

]

Lactate

LOx

Electro

chem

ical

1000

mdash42

nAmMminus1

mdash[442]

LOx

Electro

chem

ical

mdash001ndash5

mM

78nA

mMminus1

mdash[38]

LOxluminollowast

Electro

chem

iluminescent

5001ndash05m

Mmdash

5120583M

[36]

LOxPBlowast

Electro

chem

ical

mdash01ndash10

mM

0553120583

AmMminus1

50120583M

[44]

LOxPBlowast

Electro

chem

ical

401ndash5m


300120583

M[45]

Phosph

ate

PyOx

Electro

chem

ical

5075

ndash625120583M

52389

nAmMminus1

36120583

M[53]

Alpha-amylase

GDG

Ox

Electro

chem

ical

100

0ndash30

UmLminus

1mdash

mdash[62]

GDM

RGOx

Electro

chem

ical

3501ndash3m

Mmdash

5012

nM(530m

in)

[63]

Gal-G

2-CN

POptical

50ndash

200U

mLminus

1mdash

mdash[66]

Gal-G

2-CN

POptical

3010ndash140

UmLminus

1mdash

mdash[65]

Gal-G

2-CN

POptical

2510ndash230

UmLminus

1mdash

mdash[64]

MPGOxPO

xElectro

chem

ical

500ndash

190U

mLminus

1mdash

mdash[67]

AmylaseA

g-Ablowast

Immun

oelectrochem

ical


mLminus

1mdash

157p

gmLminus1

[68]

GDG

OxFclowast

Electro

chem

ical

mdash60ndash8

40UmLminus

1mdash

17UmLminus1

[70]

GDM

RGOxPBlowast

Electro

chem

ical

mdash5ndash250U

mLminus

114nA

Uminus1

5UmLminus1

[71]

lowastTh

ebiorecognitio


with

thechromogen

that

provides

thechange

ofcolour

foro

pticaldeterm

inations

with

theredo

xmediators

that

facilitateele

ctrons

transfe

rfor

electrochem

ical

determ

inations








































9 Conclusion



Table2Summaryof

ther

eportedSL

immun


Biom

arker

Biorecognitio

nTransducer

Samplev

olum

e(120583L)

Working

range

Sensitivity

Detectio

nlim

it(D

L)Re

ference

Cortisol

CortisolAg-Ab

AP

Immun

oelectrochem

ical

30mdash

mdash021ng

mLminus1

[108]


Optical

mdash15

ndash10n

gmLminus

1mdash

10ng

mLminus1

[109]

Cortisol-link

erconjugate-Ab

Optical

5091ndash934

pgmLminus1

162R

UmLngminus1

49pg

mLminus1

[74]

GOx-cortiso

lcon

jugateA

g-Ab

Optical

100

1ndash10ng

mLminus

1mdash

mdash[110]

GOx-cortiso

lcon

jugateA

g-Ab

Immun

oelectrochem

ical

4001ndash10ng

mLminus

1mdash

mdash[111]

CortisolAg-Ab

Immun

oelectrochem

ical

mdash1p

Mminus1 120583

M1165

kΩMminus1

1pM

[112]


ortisolAb


iresistors

mdash0001ndash10ng

mLminus

11397n

gmLminus1

1pgm

Lminus1

[113]

Cortisol

conjugate-BS

AA

nti-c

ortisolAb

Immun

oelectrochem

ical

10100p

Mto

100n

M540Ω

Mminus1

1pM

[115]

Testo

sterone

Testo

sterone-link

erconjugate-Ag-Ab

Optical

mdash25ndash250

pgmLminus

145

RUmLngminus1

154pg

mLminus1

[87]

Immun

oglobu

linA(Ig

A)

IgA-

antiIgA

Piezoelectric

1000

0mdash

mdashmdash

[138]

SAG1antigen

mdashmdash

mdashmdash

mdash[162]

IgGHIV

target

Electro

chem

ical

mdashmdash

mdash1n

M[14

2]Streptococcus

pyogenes(S

pyogenes)b

acteria

Anti-S

pyogenes

Ab-Ptyr-biotin-N

eutrAv

idin

Immun

oelectrochem

ical

mdash100to

105cells

per10120583

Lmdash

mdash[139]

Interle

ukin-8

(IL-8)

IL-8

capturep

robe-IL-8

targetFluorescent

Optical

506fMndash12p

Mmdash

40fM

[144]

IL-8

capturep

robe-IL-8

targetFluorescent

Optical

20mdash

mdash08p

M[159]

Cancer

antig

ens

15-3

(CA15-3)

Anti-C

A15-3

AbOptical


1mdash

mdash[158]

Anti-C

A153Ab

Optical


10001ndash001Um

L0001U

mL

[163]

IL-8

mRN

Aandproteinprob

eElectro

chem

ical

mdash5fMndash50p

M

10ndash12500

pgm

L39fM

74pgm

Lmdash

[160]








Acknowledgments


References


















































































































































































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology




















6 Salivary Hormones





Table1Summaryof

thea

nalytic

alparametersfor

catalytic


theliterature

Biom

arker

Biorecognitio

nTransducer

Samplev

olum

e(120583L)

Working

range

Sensitivity

Detectio

nlim

it(D

L)Re

ference

Glucose

GOx

Electro

chem

ical

200

01ndash10mgd

Lminus1

mdashmdash

[31]

GOx

Electro

chem

ical

5001ndash10mgd

Lminus1

mdashmdash

[32]

GOxFclowast

Electro

chem

ical

mdash0ndash

22m

M2145n


1120583M

[33]

GOxPO

xTM

BZlowast

Optical

02

0ndash10mgd

Lminus1

mdashmdash

[3435]

GOxPO

xTM

BZlowast

Optical

02

mdashmdash

mdash[19

]

Lactate

LOx

Electro

chem

ical

1000

mdash42

nAmMminus1

mdash[442]

LOx

Electro

chem

ical

mdash001ndash5

mM

78nA

mMminus1

mdash[38]

LOxluminollowast

Electro

chem

iluminescent

5001ndash05m

Mmdash

5120583M

[36]

LOxPBlowast

Electro

chem

ical

mdash01ndash10

mM

0553120583

AmMminus1

50120583M

[44]

LOxPBlowast

Electro

chem

ical

401ndash5m


300120583

M[45]

Phosph

ate

PyOx

Electro

chem

ical

5075

ndash625120583M

52389

nAmMminus1

36120583

M[53]

Alpha-amylase

GDG

Ox

Electro

chem

ical

100

0ndash30

UmLminus

1mdash

mdash[62]

GDM

RGOx

Electro

chem

ical

3501ndash3m

Mmdash

5012

nM(530m

in)

[63]

Gal-G

2-CN

POptical

50ndash

200U

mLminus

1mdash

mdash[66]

Gal-G

2-CN

POptical

3010ndash140

UmLminus

1mdash

mdash[65]

Gal-G

2-CN

POptical

2510ndash230

UmLminus

1mdash

mdash[64]

MPGOxPO

xElectro

chem

ical

500ndash

190U

mLminus

1mdash

mdash[67]

AmylaseA

g-Ablowast

Immun

oelectrochem

ical


mLminus

1mdash

157p

gmLminus1

[68]

GDG

OxFclowast

Electro

chem

ical

mdash60ndash8

40UmLminus

1mdash

17UmLminus1

[70]

GDM

RGOxPBlowast

Electro

chem

ical

mdash5ndash250U

mLminus

114nA

Uminus1

5UmLminus1

[71]

lowastTh

ebiorecognitio


with

thechromogen

that

provides

thechange

ofcolour

foro

pticaldeterm

inations

with

theredo

xmediators

that

facilitateele

ctrons

transfe

rfor

electrochem

ical

determ

inations








































9 Conclusion



Table2Summaryof

ther

eportedSL

immun


Biom

arker

Biorecognitio

nTransducer

Samplev

olum

e(120583L)

Working

range

Sensitivity

Detectio

nlim

it(D

L)Re

ference

Cortisol

CortisolAg-Ab

AP

Immun

oelectrochem

ical

30mdash

mdash021ng

mLminus1

[108]


Optical

mdash15

ndash10n

gmLminus

1mdash

10ng

mLminus1

[109]

Cortisol-link

erconjugate-Ab

Optical

5091ndash934

pgmLminus1

162R

UmLngminus1

49pg

mLminus1

[74]

GOx-cortiso

lcon

jugateA

g-Ab

Optical

100

1ndash10ng

mLminus

1mdash

mdash[110]

GOx-cortiso

lcon

jugateA

g-Ab

Immun

oelectrochem

ical

4001ndash10ng

mLminus

1mdash

mdash[111]

CortisolAg-Ab

Immun

oelectrochem

ical

mdash1p

Mminus1 120583

M1165

kΩMminus1

1pM

[112]


ortisolAb


iresistors

mdash0001ndash10ng

mLminus

11397n

gmLminus1

1pgm

Lminus1

[113]

Cortisol

conjugate-BS

AA

nti-c

ortisolAb

Immun

oelectrochem

ical

10100p

Mto

100n

M540Ω

Mminus1

1pM

[115]

Testo

sterone

Testo

sterone-link

erconjugate-Ag-Ab

Optical

mdash25ndash250

pgmLminus

145

RUmLngminus1

154pg

mLminus1

[87]

Immun

oglobu

linA(Ig

A)

IgA-

antiIgA

Piezoelectric

1000

0mdash

mdashmdash

[138]

SAG1antigen

mdashmdash

mdashmdash

mdash[162]

IgGHIV

target

Electro

chem

ical

mdashmdash

mdash1n

M[14

2]Streptococcus

pyogenes(S

pyogenes)b

acteria

Anti-S

pyogenes

Ab-Ptyr-biotin-N

eutrAv

idin

Immun

oelectrochem

ical

mdash100to

105cells

per10120583

Lmdash

mdash[139]

Interle

ukin-8

(IL-8)

IL-8

capturep

robe-IL-8

targetFluorescent

Optical

506fMndash12p

Mmdash

40fM

[144]

IL-8

capturep

robe-IL-8

targetFluorescent

Optical

20mdash

mdash08p

M[159]

Cancer

antig

ens

15-3

(CA15-3)

Anti-C

A15-3

AbOptical


1mdash

mdash[158]

Anti-C

A153Ab

Optical


10001ndash001Um

L0001U

mL

[163]

IL-8

mRN

Aandproteinprob

eElectro

chem

ical

mdash5fMndash50p

M

10ndash12500

pgm

L39fM

74pgm

Lmdash

[160]








Acknowledgments


References


















































































































































































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology









6 Salivary Hormones





Table1Summaryof

thea

nalytic

alparametersfor

catalytic


theliterature

Biom

arker

Biorecognitio

nTransducer

Samplev

olum

e(120583L)

Working

range

Sensitivity

Detectio

nlim

it(D

L)Re

ference

Glucose

GOx

Electro

chem

ical

200

01ndash10mgd

Lminus1

mdashmdash

[31]

GOx

Electro

chem

ical

5001ndash10mgd

Lminus1

mdashmdash

[32]

GOxFclowast

Electro

chem

ical

mdash0ndash

22m

M2145n


1120583M

[33]

GOxPO

xTM

BZlowast

Optical

02

0ndash10mgd

Lminus1

mdashmdash

[3435]

GOxPO

xTM

BZlowast

Optical

02

mdashmdash

mdash[19

]

Lactate

LOx

Electro

chem

ical

1000

mdash42

nAmMminus1

mdash[442]

LOx

Electro

chem

ical

mdash001ndash5

mM

78nA

mMminus1

mdash[38]

LOxluminollowast

Electro

chem

iluminescent

5001ndash05m

Mmdash

5120583M

[36]

LOxPBlowast

Electro

chem

ical

mdash01ndash10

mM

0553120583

AmMminus1

50120583M

[44]

LOxPBlowast

Electro

chem

ical

401ndash5m


300120583

M[45]

Phosph

ate

PyOx

Electro

chem

ical

5075

ndash625120583M

52389

nAmMminus1

36120583

M[53]

Alpha-amylase

GDG

Ox

Electro

chem

ical

100

0ndash30

UmLminus

1mdash

mdash[62]

GDM

RGOx

Electro

chem

ical

3501ndash3m

Mmdash

5012

nM(530m

in)

[63]

Gal-G

2-CN

POptical

50ndash

200U

mLminus

1mdash

mdash[66]

Gal-G

2-CN

POptical

3010ndash140

UmLminus

1mdash

mdash[65]

Gal-G

2-CN

POptical

2510ndash230

UmLminus

1mdash

mdash[64]

MPGOxPO

xElectro

chem

ical

500ndash

190U

mLminus

1mdash

mdash[67]

AmylaseA

g-Ablowast

Immun

oelectrochem

ical


mLminus

1mdash

157p

gmLminus1

[68]

GDG

OxFclowast

Electro

chem

ical

mdash60ndash8

40UmLminus

1mdash

17UmLminus1

[70]

GDM

RGOxPBlowast

Electro

chem

ical

mdash5ndash250U

mLminus

114nA

Uminus1

5UmLminus1

[71]

lowastTh

ebiorecognitio


with

thechromogen

that

provides

thechange

ofcolour

foro

pticaldeterm

inations

with

theredo

xmediators

that

facilitateele

ctrons

transfe

rfor

electrochem

ical

determ

inations








































9 Conclusion



Table2Summaryof

ther

eportedSL

immun


Biom

arker

Biorecognitio

nTransducer

Samplev

olum

e(120583L)

Working

range

Sensitivity

Detectio

nlim

it(D

L)Re

ference

Cortisol

CortisolAg-Ab

AP

Immun

oelectrochem

ical

30mdash

mdash021ng

mLminus1

[108]


Optical

mdash15

ndash10n

gmLminus

1mdash

10ng

mLminus1

[109]

Cortisol-link

erconjugate-Ab

Optical

5091ndash934

pgmLminus1

162R

UmLngminus1

49pg

mLminus1

[74]

GOx-cortiso

lcon

jugateA

g-Ab

Optical

100

1ndash10ng

mLminus

1mdash

mdash[110]

GOx-cortiso

lcon

jugateA

g-Ab

Immun

oelectrochem

ical

4001ndash10ng

mLminus

1mdash

mdash[111]

CortisolAg-Ab

Immun

oelectrochem

ical

mdash1p

Mminus1 120583

M1165

kΩMminus1

1pM

[112]


ortisolAb


iresistors

mdash0001ndash10ng

mLminus

11397n

gmLminus1

1pgm

Lminus1

[113]

Cortisol

conjugate-BS

AA

nti-c

ortisolAb

Immun

oelectrochem

ical

10100p

Mto

100n

M540Ω

Mminus1

1pM

[115]

Testo

sterone

Testo

sterone-link

erconjugate-Ag-Ab

Optical

mdash25ndash250

pgmLminus

145

RUmLngminus1

154pg

mLminus1

[87]

Immun

oglobu

linA(Ig

A)

IgA-

antiIgA

Piezoelectric

1000

0mdash

mdashmdash

[138]

SAG1antigen

mdashmdash

mdashmdash

mdash[162]

IgGHIV

target

Electro

chem

ical

mdashmdash

mdash1n

M[14

2]Streptococcus

pyogenes(S

pyogenes)b

acteria

Anti-S

pyogenes

Ab-Ptyr-biotin-N

eutrAv

idin

Immun

oelectrochem

ical

mdash100to

105cells

per10120583

Lmdash

mdash[139]

Interle

ukin-8

(IL-8)

IL-8

capturep

robe-IL-8

targetFluorescent

Optical

506fMndash12p

Mmdash

40fM

[144]

IL-8

capturep

robe-IL-8

targetFluorescent

Optical

20mdash

mdash08p

M[159]

Cancer

antig

ens

15-3

(CA15-3)

Anti-C

A15-3

AbOptical


1mdash

mdash[158]

Anti-C

A153Ab

Optical


10001ndash001Um

L0001U

mL

[163]

IL-8

mRN

Aandproteinprob

eElectro

chem

ical

mdash5fMndash50p

M

10ndash12500

pgm

L39fM

74pgm

Lmdash

[160]








Acknowledgments


References


















































































































































































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology


Table1Summaryof

thea

nalytic

alparametersfor

catalytic


theliterature

Biom

arker

Biorecognitio

nTransducer

Samplev

olum

e(120583L)

Working

range

Sensitivity

Detectio

nlim

it(D

L)Re

ference

Glucose

GOx

Electro

chem

ical

200

01ndash10mgd

Lminus1

mdashmdash

[31]

GOx

Electro

chem

ical

5001ndash10mgd

Lminus1

mdashmdash

[32]

GOxFclowast

Electro

chem

ical

mdash0ndash

22m

M2145n


1120583M

[33]

GOxPO

xTM

BZlowast

Optical

02

0ndash10mgd

Lminus1

mdashmdash

[3435]

GOxPO

xTM

BZlowast

Optical

02

mdashmdash

mdash[19

]

Lactate

LOx

Electro

chem

ical

1000

mdash42

nAmMminus1

mdash[442]

LOx

Electro

chem

ical

mdash001ndash5

mM

78nA

mMminus1

mdash[38]

LOxluminollowast

Electro

chem

iluminescent

5001ndash05m

Mmdash

5120583M

[36]

LOxPBlowast

Electro

chem

ical

mdash01ndash10

mM

0553120583

AmMminus1

50120583M

[44]

LOxPBlowast

Electro

chem

ical

401ndash5m


300120583

M[45]

Phosph

ate

PyOx

Electro

chem

ical

5075

ndash625120583M

52389

nAmMminus1

36120583

M[53]

Alpha-amylase

GDG

Ox

Electro

chem

ical

100

0ndash30

UmLminus

1mdash

mdash[62]

GDM

RGOx

Electro

chem

ical

3501ndash3m

Mmdash

5012

nM(530m

in)

[63]

Gal-G

2-CN

POptical

50ndash

200U

mLminus

1mdash

mdash[66]

Gal-G

2-CN

POptical

3010ndash140

UmLminus

1mdash

mdash[65]

Gal-G

2-CN

POptical

2510ndash230

UmLminus

1mdash

mdash[64]

MPGOxPO

xElectro

chem

ical

500ndash

190U

mLminus

1mdash

mdash[67]

AmylaseA

g-Ablowast

Immun

oelectrochem

ical


mLminus

1mdash

157p

gmLminus1

[68]

GDG

OxFclowast

Electro

chem

ical

mdash60ndash8

40UmLminus

1mdash

17UmLminus1

[70]

GDM

RGOxPBlowast

Electro

chem

ical

mdash5ndash250U

mLminus

114nA

Uminus1

5UmLminus1

[71]

lowastTh

ebiorecognitio


with

thechromogen

that

provides

thechange

ofcolour

foro

pticaldeterm

inations

with

theredo

xmediators

that

facilitateele

ctrons

transfe

rfor

electrochem

ical

determ

inations








































9 Conclusion



Table2Summaryof

ther

eportedSL

immun


Biom

arker

Biorecognitio

nTransducer

Samplev

olum

e(120583L)

Working

range

Sensitivity

Detectio

nlim

it(D

L)Re

ference

Cortisol

CortisolAg-Ab

AP

Immun

oelectrochem

ical

30mdash

mdash021ng

mLminus1

[108]


Optical

mdash15

ndash10n

gmLminus

1mdash

10ng

mLminus1

[109]

Cortisol-link

erconjugate-Ab

Optical

5091ndash934

pgmLminus1

162R

UmLngminus1

49pg

mLminus1

[74]

GOx-cortiso

lcon

jugateA

g-Ab

Optical

100

1ndash10ng

mLminus

1mdash

mdash[110]

GOx-cortiso

lcon

jugateA

g-Ab

Immun

oelectrochem

ical

4001ndash10ng

mLminus

1mdash

mdash[111]

CortisolAg-Ab

Immun

oelectrochem

ical

mdash1p

Mminus1 120583

M1165

kΩMminus1

1pM

[112]


ortisolAb


iresistors

mdash0001ndash10ng

mLminus

11397n

gmLminus1

1pgm

Lminus1

[113]

Cortisol

conjugate-BS

AA

nti-c

ortisolAb

Immun

oelectrochem

ical

10100p

Mto

100n

M540Ω

Mminus1

1pM

[115]

Testo

sterone

Testo

sterone-link

erconjugate-Ag-Ab

Optical

mdash25ndash250

pgmLminus

145

RUmLngminus1

154pg

mLminus1

[87]

Immun

oglobu

linA(Ig

A)

IgA-

antiIgA

Piezoelectric

1000

0mdash

mdashmdash

[138]

SAG1antigen

mdashmdash

mdashmdash

mdash[162]

IgGHIV

target

Electro

chem

ical

mdashmdash

mdash1n

M[14

2]Streptococcus

pyogenes(S

pyogenes)b

acteria

Anti-S

pyogenes

Ab-Ptyr-biotin-N

eutrAv

idin

Immun

oelectrochem

ical

mdash100to

105cells

per10120583

Lmdash

mdash[139]

Interle

ukin-8

(IL-8)

IL-8

capturep

robe-IL-8

targetFluorescent

Optical

506fMndash12p

Mmdash

40fM

[144]

IL-8

capturep

robe-IL-8

targetFluorescent

Optical

20mdash

mdash08p

M[159]

Cancer

antig

ens

15-3

(CA15-3)

Anti-C

A15-3

AbOptical


1mdash

mdash[158]

Anti-C

A153Ab

Optical


10001ndash001Um

L0001U

mL

[163]

IL-8

mRN

Aandproteinprob

eElectro

chem

ical

mdash5fMndash50p

M

10ndash12500

pgm

L39fM

74pgm

Lmdash

[160]








Acknowledgments


References


















































































































































































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology








































9 Conclusion



Table2Summaryof

ther

eportedSL

immun


Biom

arker

Biorecognitio

nTransducer

Samplev

olum

e(120583L)

Working

range

Sensitivity

Detectio

nlim

it(D

L)Re

ference

Cortisol

CortisolAg-Ab

AP

Immun

oelectrochem

ical

30mdash

mdash021ng

mLminus1

[108]


Optical

mdash15

ndash10n

gmLminus

1mdash

10ng

mLminus1

[109]

Cortisol-link

erconjugate-Ab

Optical

5091ndash934

pgmLminus1

162R

UmLngminus1

49pg

mLminus1

[74]

GOx-cortiso

lcon

jugateA

g-Ab

Optical

100

1ndash10ng

mLminus

1mdash

mdash[110]

GOx-cortiso

lcon

jugateA

g-Ab

Immun

oelectrochem

ical

4001ndash10ng

mLminus

1mdash

mdash[111]

CortisolAg-Ab

Immun

oelectrochem

ical

mdash1p

Mminus1 120583

M1165

kΩMminus1

1pM

[112]


ortisolAb


iresistors

mdash0001ndash10ng

mLminus

11397n

gmLminus1

1pgm

Lminus1

[113]

Cortisol

conjugate-BS

AA

nti-c

ortisolAb

Immun

oelectrochem

ical

10100p

Mto

100n

M540Ω

Mminus1

1pM

[115]

Testo

sterone

Testo

sterone-link

erconjugate-Ag-Ab

Optical

mdash25ndash250

pgmLminus

145

RUmLngminus1

154pg

mLminus1

[87]

Immun

oglobu

linA(Ig

A)

IgA-

antiIgA

Piezoelectric

1000

0mdash

mdashmdash

[138]

SAG1antigen

mdashmdash

mdashmdash

mdash[162]

IgGHIV

target

Electro

chem

ical

mdashmdash

mdash1n

M[14

2]Streptococcus

pyogenes(S

pyogenes)b

acteria

Anti-S

pyogenes

Ab-Ptyr-biotin-N

eutrAv

idin

Immun

oelectrochem

ical

mdash100to

105cells

per10120583

Lmdash

mdash[139]

Interle

ukin-8

(IL-8)

IL-8

capturep

robe-IL-8

targetFluorescent

Optical

506fMndash12p

Mmdash

40fM

[144]

IL-8

capturep

robe-IL-8

targetFluorescent

Optical

20mdash

mdash08p

M[159]

Cancer

antig

ens

15-3

(CA15-3)

Anti-C

A15-3

AbOptical


1mdash

mdash[158]

Anti-C

A153Ab

Optical


10001ndash001Um

L0001U

mL

[163]

IL-8

mRN

Aandproteinprob

eElectro

chem

ical

mdash5fMndash50p

M

10ndash12500

pgm

L39fM

74pgm

Lmdash

[160]








Acknowledgments


References


















































































































































































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology































9 Conclusion



Table2Summaryof

ther

eportedSL

immun


Biom

arker

Biorecognitio

nTransducer

Samplev

olum

e(120583L)

Working

range

Sensitivity

Detectio

nlim

it(D

L)Re

ference

Cortisol

CortisolAg-Ab

AP

Immun

oelectrochem

ical

30mdash

mdash021ng

mLminus1

[108]


Optical

mdash15

ndash10n

gmLminus

1mdash

10ng

mLminus1

[109]

Cortisol-link

erconjugate-Ab

Optical

5091ndash934

pgmLminus1

162R

UmLngminus1

49pg

mLminus1

[74]

GOx-cortiso

lcon

jugateA

g-Ab

Optical

100

1ndash10ng

mLminus

1mdash

mdash[110]

GOx-cortiso

lcon

jugateA

g-Ab

Immun

oelectrochem

ical

4001ndash10ng

mLminus

1mdash

mdash[111]

CortisolAg-Ab

Immun

oelectrochem

ical

mdash1p

Mminus1 120583

M1165

kΩMminus1

1pM

[112]


ortisolAb


iresistors

mdash0001ndash10ng

mLminus

11397n

gmLminus1

1pgm

Lminus1

[113]

Cortisol

conjugate-BS

AA

nti-c

ortisolAb

Immun

oelectrochem

ical

10100p

Mto

100n

M540Ω

Mminus1

1pM

[115]

Testo

sterone

Testo

sterone-link

erconjugate-Ag-Ab

Optical

mdash25ndash250

pgmLminus

145

RUmLngminus1

154pg

mLminus1

[87]

Immun

oglobu

linA(Ig

A)

IgA-

antiIgA

Piezoelectric

1000

0mdash

mdashmdash

[138]

SAG1antigen

mdashmdash

mdashmdash

mdash[162]

IgGHIV

target

Electro

chem

ical

mdashmdash

mdash1n

M[14

2]Streptococcus

pyogenes(S

pyogenes)b

acteria

Anti-S

pyogenes

Ab-Ptyr-biotin-N

eutrAv

idin

Immun

oelectrochem

ical

mdash100to

105cells

per10120583

Lmdash

mdash[139]

Interle

ukin-8

(IL-8)

IL-8

capturep

robe-IL-8

targetFluorescent

Optical

506fMndash12p

Mmdash

40fM

[144]

IL-8

capturep

robe-IL-8

targetFluorescent

Optical

20mdash

mdash08p

M[159]

Cancer

antig

ens

15-3

(CA15-3)

Anti-C

A15-3

AbOptical


1mdash

mdash[158]

Anti-C

A153Ab

Optical


10001ndash001Um

L0001U

mL

[163]

IL-8

mRN

Aandproteinprob

eElectro

chem

ical

mdash5fMndash50p

M

10ndash12500

pgm

L39fM

74pgm

Lmdash

[160]








Acknowledgments


References


















































































































































































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology




















9 Conclusion



Table2Summaryof

ther

eportedSL

immun


Biom

arker

Biorecognitio

nTransducer

Samplev

olum

e(120583L)

Working

range

Sensitivity

Detectio

nlim

it(D

L)Re

ference

Cortisol

CortisolAg-Ab

AP

Immun

oelectrochem

ical

30mdash

mdash021ng

mLminus1

[108]


Optical

mdash15

ndash10n

gmLminus

1mdash

10ng

mLminus1

[109]

Cortisol-link

erconjugate-Ab

Optical

5091ndash934

pgmLminus1

162R

UmLngminus1

49pg

mLminus1

[74]

GOx-cortiso

lcon

jugateA

g-Ab

Optical

100

1ndash10ng

mLminus

1mdash

mdash[110]

GOx-cortiso

lcon

jugateA

g-Ab

Immun

oelectrochem

ical

4001ndash10ng

mLminus

1mdash

mdash[111]

CortisolAg-Ab

Immun

oelectrochem

ical

mdash1p

Mminus1 120583

M1165

kΩMminus1

1pM

[112]


ortisolAb


iresistors

mdash0001ndash10ng

mLminus

11397n

gmLminus1

1pgm

Lminus1

[113]

Cortisol

conjugate-BS

AA

nti-c

ortisolAb

Immun

oelectrochem

ical

10100p

Mto

100n

M540Ω

Mminus1

1pM

[115]

Testo

sterone

Testo

sterone-link

erconjugate-Ag-Ab

Optical

mdash25ndash250

pgmLminus

145

RUmLngminus1

154pg

mLminus1

[87]

Immun

oglobu

linA(Ig

A)

IgA-

antiIgA

Piezoelectric

1000

0mdash

mdashmdash

[138]

SAG1antigen

mdashmdash

mdashmdash

mdash[162]

IgGHIV

target

Electro

chem

ical

mdashmdash

mdash1n

M[14

2]Streptococcus

pyogenes(S

pyogenes)b

acteria

Anti-S

pyogenes

Ab-Ptyr-biotin-N

eutrAv

idin

Immun

oelectrochem

ical

mdash100to

105cells

per10120583

Lmdash

mdash[139]

Interle

ukin-8

(IL-8)

IL-8

capturep

robe-IL-8

targetFluorescent

Optical

506fMndash12p

Mmdash

40fM

[144]

IL-8

capturep

robe-IL-8

targetFluorescent

Optical

20mdash

mdash08p

M[159]

Cancer

antig

ens

15-3

(CA15-3)

Anti-C

A15-3

AbOptical


1mdash

mdash[158]

Anti-C

A153Ab

Optical


10001ndash001Um

L0001U

mL

[163]

IL-8

mRN

Aandproteinprob

eElectro

chem

ical

mdash5fMndash50p

M

10ndash12500

pgm

L39fM

74pgm

Lmdash

[160]








Acknowledgments


References


















































































































































































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology










9 Conclusion



Table2Summaryof

ther

eportedSL

immun


Biom

arker

Biorecognitio

nTransducer

Samplev

olum

e(120583L)

Working

range

Sensitivity

Detectio

nlim

it(D

L)Re

ference

Cortisol

CortisolAg-Ab

AP

Immun

oelectrochem

ical

30mdash

mdash021ng

mLminus1

[108]


Optical

mdash15

ndash10n

gmLminus

1mdash

10ng

mLminus1

[109]

Cortisol-link

erconjugate-Ab

Optical

5091ndash934

pgmLminus1

162R

UmLngminus1

49pg

mLminus1

[74]

GOx-cortiso

lcon

jugateA

g-Ab

Optical

100

1ndash10ng

mLminus

1mdash

mdash[110]

GOx-cortiso

lcon

jugateA

g-Ab

Immun

oelectrochem

ical

4001ndash10ng

mLminus

1mdash

mdash[111]

CortisolAg-Ab

Immun

oelectrochem

ical

mdash1p

Mminus1 120583

M1165

kΩMminus1

1pM

[112]


ortisolAb


iresistors

mdash0001ndash10ng

mLminus

11397n

gmLminus1

1pgm

Lminus1

[113]

Cortisol

conjugate-BS

AA

nti-c

ortisolAb

Immun

oelectrochem

ical

10100p

Mto

100n

M540Ω

Mminus1

1pM

[115]

Testo

sterone

Testo

sterone-link

erconjugate-Ag-Ab

Optical

mdash25ndash250

pgmLminus

145

RUmLngminus1

154pg

mLminus1

[87]

Immun

oglobu

linA(Ig

A)

IgA-

antiIgA

Piezoelectric

1000

0mdash

mdashmdash

[138]

SAG1antigen

mdashmdash

mdashmdash

mdash[162]

IgGHIV

target

Electro

chem

ical

mdashmdash

mdash1n

M[14

2]Streptococcus

pyogenes(S

pyogenes)b

acteria

Anti-S

pyogenes

Ab-Ptyr-biotin-N

eutrAv

idin

Immun

oelectrochem

ical

mdash100to

105cells

per10120583

Lmdash

mdash[139]

Interle

ukin-8

(IL-8)

IL-8

capturep

robe-IL-8

targetFluorescent

Optical

506fMndash12p

Mmdash

40fM

[144]

IL-8

capturep

robe-IL-8

targetFluorescent

Optical

20mdash

mdash08p

M[159]

Cancer

antig

ens

15-3

(CA15-3)

Anti-C

A15-3

AbOptical


1mdash

mdash[158]

Anti-C

A153Ab

Optical


10001ndash001Um

L0001U

mL

[163]

IL-8

mRN

Aandproteinprob

eElectro

chem

ical

mdash5fMndash50p

M

10ndash12500

pgm

L39fM

74pgm

Lmdash

[160]








Acknowledgments


References


















































































































































































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology


Table2Summaryof

ther

eportedSL

immun


Biom

arker

Biorecognitio

nTransducer

Samplev

olum

e(120583L)

Working

range

Sensitivity

Detectio

nlim

it(D

L)Re

ference

Cortisol

CortisolAg-Ab

AP

Immun

oelectrochem

ical

30mdash

mdash021ng

mLminus1

[108]


Optical

mdash15

ndash10n

gmLminus

1mdash

10ng

mLminus1

[109]

Cortisol-link

erconjugate-Ab

Optical

5091ndash934

pgmLminus1

162R

UmLngminus1

49pg

mLminus1

[74]

GOx-cortiso

lcon

jugateA

g-Ab

Optical

100

1ndash10ng

mLminus

1mdash

mdash[110]

GOx-cortiso

lcon

jugateA

g-Ab

Immun

oelectrochem

ical

4001ndash10ng

mLminus

1mdash

mdash[111]

CortisolAg-Ab

Immun

oelectrochem

ical

mdash1p

Mminus1 120583

M1165

kΩMminus1

1pM

[112]


ortisolAb


iresistors

mdash0001ndash10ng

mLminus

11397n

gmLminus1

1pgm

Lminus1

[113]

Cortisol

conjugate-BS

AA

nti-c

ortisolAb

Immun

oelectrochem

ical

10100p

Mto

100n

M540Ω

Mminus1

1pM

[115]

Testo

sterone

Testo

sterone-link

erconjugate-Ag-Ab

Optical

mdash25ndash250

pgmLminus

145

RUmLngminus1

154pg

mLminus1

[87]

Immun

oglobu

linA(Ig

A)

IgA-

antiIgA

Piezoelectric

1000

0mdash

mdashmdash

[138]

SAG1antigen

mdashmdash

mdashmdash

mdash[162]

IgGHIV

target

Electro

chem

ical

mdashmdash

mdash1n

M[14

2]Streptococcus

pyogenes(S

pyogenes)b

acteria

Anti-S

pyogenes

Ab-Ptyr-biotin-N

eutrAv

idin

Immun

oelectrochem

ical

mdash100to

105cells

per10120583

Lmdash

mdash[139]

Interle

ukin-8

(IL-8)

IL-8

capturep

robe-IL-8

targetFluorescent

Optical

506fMndash12p

Mmdash

40fM

[144]

IL-8

capturep

robe-IL-8

targetFluorescent

Optical

20mdash

mdash08p

M[159]

Cancer

antig

ens

15-3

(CA15-3)

Anti-C

A15-3

AbOptical


1mdash

mdash[158]

Anti-C

A153Ab

Optical


10001ndash001Um

L0001U

mL

[163]

IL-8

mRN

Aandproteinprob

eElectro

chem

ical

mdash5fMndash50p

M

10ndash12500

pgm

L39fM

74pgm

Lmdash

[160]








Acknowledgments


References


















































































































































































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology








Acknowledgments


References


















































































































































































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology






































































































































































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology




































































































































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology



































































































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology

































































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology
































Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology








Volume 2014

Zoology






















Advances in

Virolog y



Volume 2014




Enzyme Research



Microbiology

Documents

Review Article Saliva-Based Biosensors: Noninvasive Monitoring …downloads.hindawi.com/journals/bmri/2014/962903.pdf · 2019-07-31 · Review Article Saliva-Based Biosensors: Noninvasive