Nanotechnology and Prime Materials - Encsusers.encs.concordia.ca/~mojtaba/elec6271/Nano-from-different-angle-2017.pdf•Nano water purifiers. •inexpensive energy generation. •Pollution

Nanotechnology and Prime Materials

Applications (cont…)

• Higher surface area

• Higher optical absorption

• Higher solubility

Applications

• Nano medicine

• Nano biotechnology

• Green nanotechnology

• Energy applications

• Industrial applications

• Tunable electronic structure by reducing

the size

• Potential applications has left to explore.

Applications

• Nano water purifiers.

• inexpensive energy generation.

• Pollution trace detection and treatment.

• Radically improved formulation of drugs, diagnostics and organ replacement.

• Greater information storage and communication capacities

• Interactive ‘smart’ appliances; and increased human performance through convergent technologies.

Nanotechnology and Prime materials

• Metals:

• Iron, needle shape particles with diameters on the order of 30-100 nm are produced. Widely used in magnetic recording for analog and digital data. Iron-palladium, and Iron-platinum (strong magnetization) alloys are used for ground-water decontamination, and magnetic storage media respectively.


• Aluminum, powders with size range of 10-100

nm produced using plasma reactor. In a few

thousandths of second a rod of solid material

with a massive pulse of electrical energy,

heating it to 50,000 C, followed by rapid cooling

of the gas, the speed of cooling controls the size

of the nano-particles. It is used for optical

applications like scratch-resistant coatings for

plastic lenses, biomedical applications, fuel cells,

and solar energy applications.


• Nickel, powders are valued for their high

conductivity and high melting point.

Particles with sizes with various

nanoscales are produced using CVD, wet-

chemical processes and gas-phase

reduction. Multilayer ceramic capacitors

have become the major application for

these nanoparticles.


• Silver, known for its excellent conductivity and

antimicrobial effects. Particles with sizes range

of 10-90 nm have been used as an ingredient in

a biocide (a chemical substance killing living

organisms), in transparent conductive inks and

paste,…

• Nanofibers are defined as fibers with diameters from

few nano to few hundred nanometers.

• They have lengths up to several millimeters.

• Particles having a diameter of few nanometers

9

Electrospinning

It uses high voltage supply to draw fine

fibers from a liquid.

The high voltage produces an electrically

charged jet of polymer solution which

solidifies and leaving polymer nanofiber.

10

Electrospinning/ Nanofiber

Formation

11

2. Formation of Bending Instability

12

Experimental Results/ SEM

PVA nanofibers without silver

Experimental Results/ TEM

13

PVA nanofibers containing 1wt% of silver nitrate


14



15


Applications

16

1:10 1:1000 1:100000

Serial dilutions made the process of counting easier

Applications

17

Comparison between bactericidal activity of negative control and pure PVA at two

contact times

(NG-E)

(NG-E)

(PVA-E)

(PVA-E)

Negative control

without nanomaterial

3 hours incubation

6 hours incubation

Applications

18

PVA with 6wt%

silver nitrate

PVA with 1wt%

silver nitrate

Comparison between bactericidal activity of negative control and PVA nanofibers

incorporated with low and high concentration of silver nanoparticles after 3hours

incubation.

Negative Control

TiO2 Fabrication/ Silver Deposition

Ti-TiO2 / Cathode

Reference Electrode

Electrolyte

Pt/Anode

Potentiostat / Galvanostat

Silver Deposition/

Electrodeposition

Method:

19

TiO2 Fabrication

Effect of Fluoride concentration

0 M Ammonium Fluoride 0.15 M Ammonium Fluoride 0.36 M Ammonium Fluoride

20

Electrolyte: Ethylene glycol: DI Water (90:10 wt %)

Anodizing Voltage: 40 DC-V

Anodizing Time: 2hrs

Effect of applied voltage on tube diameters

Mean

Diameter

nm

Min

Diameter

nm

Max

Diameter

nm

SD

30 V 58.633 48.607 67.348 6.008

40 V 90.424 82.839 98.206 5.629

50 V 118.536 98.514 141.004 11.58

21

Ethylene glycol: DI Water (90:10 wt %)+ 0.15M NH4F

2hrs Anodization

Silver Deposition / SEM, EDX Results

Deposition without Doping Deposition after Doping

22

Applications

• Photo-voltaic: dye sensitised solar cells

• Gas-sensing devices

• Biomedical

• Water Disinfection

In this study growth inhibition test in Liquid Medium was

selected to evaluate the antibacterial activity against

Escherichia Coli bacteria.

23

Antibacterial test

24

1:10

Dilution1:100

Dilution

1:1000

Dilution

1:10000

Dilution

Application/ Antibacterial Test Results

Negative Control Without any inhibitors

TiO2

Ag/ TiO2

25

• Copper, nanoparticles and nanowires are

synthesized using thermal reduction or

sonochemical (using ultrasound) methods.

superior ability to conduct heat and

electricity.

Figure 4b

Figure 4. SEM micrographs of a. a single and b. a pair of CuNWs at high magnifications and c. a bundle of

nanowires at low magnification

Figure 4c

Figure 5. TEM images of the copper nanowires in the fabricated films at a. low and b. high magnifications

Figure 5b

Figure 6. Surface resistivity of copper nanowires/PMMA nanocomposites as a function of the CuNWs

volume content

V, %

0.0 0.5 1.0 1.5 2.0

/sq

10-1

100

101

102

103

104

105

106

107

108

109

1010

1011

1012

1013

1014

1015

Experimental Data

Fitted


• Gold, nanoparticles are easier to produce compare to other metals (due to the chemical stability). Colloidal gold has been used in medical applications; in a wide array of catalytic applications, e.g. for low-temperature oxidation processes, and production of other nanoparticles; optical and electrical applications, as components for various probes, sensors, and optical devices.


• Iron Oxide, nanoparticles of ferric oxide are

translucent to visible light but opaque to UV,

application in ultra thin transparent coatings with

enhanced UV-blocking capabilities. Magnetic

properties of magnetite are used to improve

various electromagnetic media for storage, like

magnetic tapes, computer hard drives, and

advance magnets.


• Aluminum Oxide, Nanosized powders of alumina, has a lower melting point, increased light absorption, improved dispersion in both aqueous and inorganic solvents. Are used to polish semiconductor wafers, in advance ceramics, and advance composite materials, for coating light bulbs and fluorescent tubes for uniform emission of light, clear coating to increase hardness, scratch and abrasion resistance, as a performance filler in tires, as a surface fiction agent, coating of high quality inkjet papers.


• Titanium Dioxide, the largest-volume

inorganic pigment produced in the world,

is widely used in surface coating, paper

and plastic applications, as a filler and

whitening agent. UV light blocking,

additive to sunscreens, cosmetics,

varnishes for the preservation of wood,

textile fibers, and packaging films.


Catalytic, photo-catalytic, self-sanitizing, self-cleaning capabilities. In photoelectrochemical solar cells, thermal coating, corrosion protection. As a component in various polymer composites to yield a product with a tunable refractive index and improved mechanical properties for photonics and electrical applications. Optical communication components (light scattering is significantly reduced).


• Zinc Oxide, larger UV blocking capability,

and very transparent for visible light, make

them invisible when they added to other

materials like cosmetics, sunscreens and

antifungal foot powders. Used in ceramics,

and rubber processing (increase elasticity,

toughness, abrasion resistance).

Nanowires are used in UV nanolasers,…


• In addition to the oxides mentioned above,

nanoparticle versions of other compounds,

such as antimony, chromium, germanium,

vanadium, tungsten, are being developed

and their possible uses are being

explored.


• Advance Composites: nano-composites are formed when nanometer-sized particles of useful additives are blended with a polymer.

Using materials made of nano composites in building structures like cars and airplanes, increases the life time of the structures and saves huge amount of energy. Advance Ceramics: ceramics in general, are inorganic, nonmetallic materials that are consolidated at high temperatures, usually starting as powder particles and ending as solid, usable forms. A typical ceramic contains complex crystals structures based on the various oxides and may involve covalent and ionic bonding.

Applications (Hydrogen Storage)

• Extremely promising form of energy storage.

• The process by which it releases its energy is

very efficient.

• The only exhaust gas produced is pure water.

• Can be burnt like any other fuel it can also be

used to produce electricity directly in a fuel cell.

• No need of higher operating temperatures.

Requirements and issues

• Materials must possess

(1) High hydrogen absorption capacity

(2) Fast hydrogenation dehydrogenation

(3) minimal deterioration during

hydrogenation cycling.

40

Advantages of using nanomaterials

• The absorption-release characteristics can be

fine-tuned by controlling the particle sizes

• Usage of nanoparticles reduces diffusion

distances for hydrogen and hence improves

the hydrogen exchange

• The increased porosity and smaller size lead

to increased diffusion-limited rates.

• High surface area to volume ratio increases

the possibility of physisorption and

chemisorption of hydrogen atoms

41

Nanotechnology and Environment

Growing world population and need for larger natural

resources which in turn has a negative impact on the

environment.

Nanotechnology can contribute solving the problems . It

offers solutions to problems of resource usage, energy

consumption, and waste generation. Less materials needed

for product fabrication; better reuse of waste materials will be

possible; and there will be new and renewable energy

sources.

Environmental improvements will be enabled by smart

devices for environmental monitoring, pollution detection

and control, and purification and remediation of polluted

water, contaminated air and soil

For example, billions of batteries disposed in landfills

pose an environmental problem, they also are a

complete waste of a potential and cheap raw material.

Batteries contain heavy metals such as mercury, lead,

cadmium, and nickel, which can contaminate the

environment.

Researchers have managed to recover pure zinc

oxide nanoparticles from spent Zn-MnO2 batteries

alkaline batteries.

Nanotechnologies can play a role in providing a secure drinking

water supply by enhancing purification and decontamination.

They can offer more targeted and less concentrated chemical

usage.

Using nano catalysts in the transport and chemical industries to

improve the efficiency of manufacturing systems, and reducing

wastes it can keep the environment clean.

The ability to detect the presence of toxic agents in our ecosystem,

air, water, and soil is of great importance for our health and the

protection of our environment.

Sensors which are less bulky, simple to operate, sensitive, fast,

and less costly can be developed using nanotechnology for

measurements and environmental monitoring.

For example, titanate nanofibers are used of as absorbents to

remove radioactive ions from water. It was found that the unique

structural properties of titanate nanotubes and nanofibers make them

superior materials for removal of radioactive cesium and iodine ions

in water.

To clean up oil spills, Conventional clean-up techniques are not

adequate to solve the problem of massive oil spills. In recent years,

works are done to use nanotechnology as a potential solution to

clean up oil spills. Several nanoparticles and molecules are

developed and tested to either absorb or convert the oil spills for

easier removal.

Hydrogen production from sunlight

While hydrogen fuel is a clean energy carrier. However, we need to produce

hydrogen, and that can be done using a several ways.

One way is the gasification of coal which the bu product is very dirty. Another way

is using electrolysis to generate hydrogen from water. In this technique, using

renewable energy resources like wind, and solar is the cleanest way.

Working on the nanoscale, it is shown that an inexpensive and environmentally

friendly light harvesting nanocrystal array can be combined with a low-cost

electrocatalyst that contains abundant elements to fabricate an inexpensive and

stable system for photoelectrochemical hydrogen production.

Nanotechnology from Different

Angle

Nanotechnology from Different Angle

No matter which way you turn, nanotechnology seems poised to impact our lives to some degree over the coming years. As materials, structures, and devices are engineered in the nanometer size range, unique properties emerge that can potentially be exploited in many ways. The technology associated with manipulation at the nanoscale—nanotechnology—is underpinning research and development into new materials, medical diagnostics and therapeutics, energy management, sensors, biological interfaces, and electronics with properties that have the potential to revolutionize our society.


• First-generation nanotechnology products are commercially available now, and increasing global investment in nanotechnology suggests we are only at the beginning of what some have called "the next industrial revolution.” However, as with previous industrial revolutions, the potential societal and economic promise of nanotechnology needs to be tempered by possible negative implications.


• The need to proactively develop responsible nanotechnology has been highlighted in a number of high profile reports and articles recently and is central to the many governments strategic plan for developing and implementing the technology. Nowhere will this be more important over the next few years than in workplaces where new materials, devices, and products are being manufactured.


• Nanotechnology is based on the unique properties manifest in nanometer-scale structures, and it is expected that resulting products will in turn present unique health and safety issues. The significance of these issues is not yet clear. What is becoming apparent, however, is that the successful development of nanotechnology relies on proactively understanding and addressing the potential risk to human health and safety. As occupational health researchers and professionals, this is the challenge to face today as society stands on the brink of the nanotechnology revolution.


• Unlike incidental particles, very little is known

about engineered nanoparticles and how they

interact with cells or human organisms. There

are only few papers written on the environmental

and health impacts of these particles; however,

there is a wealth of knowledge on incidental

nanoparticles and how these particles interact

with biological organisms. Questions remain

whether the engineered nanoparticles will act as

a bulk solid or a molecular system


• There is very little available information regarding the hazards and risks posed by materials employed in nanotechnologies. Based on the results of a number of reviews, there is a short information note to advise those working in the area of nanotechnologies of the most appropriate approach to control exposure with the current degree of scientific uncertainty, companies should take a precautionary approach when dealing with nanomaterials. In practical terms, this will mean that steps should be taken to contain material and reduce exposure as far as possible.


• Could the same properties that make the tiny particles so effective also turn them into efficient troublemakers inside the human body? It's one of the most intriguing aspects of nanotechnology: Commonplace materials assume unpredictable and incredible characteristics at the molecular level. Tiny rolled-up "nanotubes" of carbon graphite suddenly turn super strong and highly conductive, inert materials become highly reactive, and particles that once emitted red light appear blue on the nanoscale.


• As more and more nano-based consumer

products arrive, scientists are beginning to

worry that these unpredictable particles

are holding back a few surprises -- ones

that could harm human health or the

environment. Researchers have

conducted only a handful of studies on the

health implications of nanotechnology.


• We absolutely know how these materials behave when they are larger. But when we engineer something that small, it changes all the fundamentals. Some are so new we don't even have adequate testing methods.

•Nobody is saying here it's a minor threat or a major threat -- we just don't know.


• In the range of nano scale, thousands of

different types of particles exist, some

possibly dangerous but many others

completely harmless.

• We're looking at a whole batch of nano-

materials. You can't go classify all nano-

materials as bad or all as good."

Why Nanotechnology is Dangerous?

• Nanoparticles unknown properties

• Particles nature

• More surface area than volume ratio

• The smaller the particle the more toxic

Nanotoxicology

Potential Exposures

1. Airborne contamination of workplace

2. Handling of product/material

3. Cleaning/Maintenance activities

4. Leakage/Spillage Accidents

5. Product Drying

59

Nanotoxicology

Questions need to be addressed::

• What happens to the nanoparticles that we digest or inhaled?

• Can we trace them in our body?

• How our body react to them?

• How much of them can be eliminated?

• How the particles affect our cells and organs,

Nanotoxicology

Ecosystems Pathways:

• Air

• Water

• Soil

• Waste/wastewater/landfills


Pros & Cons

Pro: Green Materials, Green Chemistry,

Con: The toxicology of these materials maybe time and environment dependent. What is not toxic under one condition may be become toxic under different conditions.

Pro: Save materials, less materials are used as we are dealing with nanosize structures.

Con: Actually, more materials are used to produce one type of nano structure.

Pro: Save energy by producing more efficient solar cell, helping renewable energies, and so on.

Con. More energy is used to produce the nano optical sources. Plus the life cycle of these devices are not studies properly.

Pro: Environment benefits.

Con: The environment cost (in terms of money and toxicology) was never evaluated for the environmental friendly materials.


• Pro: Look at the applications and benefits of carbon nanotubes, in solar cell, water filteration, in electronics, as catalysts, in energy storage,..

• Con: have you ever checked the life cycle of these materials. Production of these materials is expensive and has a big impact on environment.

• Pro: atom by atom manufacturing, less waste of materials.

• Con: More time consuming, use various materials including more chemicals.

• Pro: Smaller structures save less materials, saves energy and help ecosystem

• Con: Smaller structure have much larger surface to volume ratio, more reactive, can cause toxicity, increases radicals in body, and damages more tissues.

Nanotechnology Challenges

• Do nanomaterials present new and

unique risks for health and safety and

for the environment?

• Can the potential benefits of

nanotechnology be achieved while

minimizing the potential risks?

Nanoparticles impacts on living organisms

There are many unknown details about the impact and interaction of nanoparticles on biological systems and more information on the response of living organisms to the presence of nanoparticles of varying shape and size, various surface to volume ration and kind of chemical composition is needed to understand in order to evaluate the level of their toxicities on living systems.


What are the effects of nanoparticles on the environment?

•There are very few publications on the effects of engineered nanoparticles on animals and plants in the environment.

•However, a number of studies have examined the uptake and effects of nanoparticles at a cellular level to evaluate their impact on humans; it can reasonably be assumed that the conclusions of these studies may be extrapolated to other species, but more research is needed to confirm this assumption. Moreover, careful examination and interpretation of existing data and careful planning of new research is required to establish the true impact of nanoparticles on the environment, and the differences with larger, conventional forms of the substances.

•Persistent insoluble nanoparticles may cause problems in the environment that are much greater than those revealed by human health assessments.

Anti-Bacterial Nano silver

• Nano Ag in socks kills

the bacteria and prevent

unpleasant odor

• Harmless to the person

wearing it

• Upon washing, Nano Ag

leaks into water supply

and kills good bacteria

67

Anti-bacterial Nano

Silver


Pros:

Efficiency and Environmental FriendlinessMolecular Scale Manufacturing ensures that very little raw material is wasted and that we make only what we intend to make, no more. Factories begin to look more like clean rooms. Many studies show how nanomaterials can be created that are not only safe, but also cost less and perform better than conventional materials.

Financial Benefits for Countries involved in NanotechnologyNanotechnology is expected to be over $3 trillion market by 2017. Each country involved, including have a bright financial future ahead when it comes to gaining money with nanotechnology.


Cons:

Arms for WarOn the instrumental level, concerns include the possibility of military applications of nanotechnology, in particular there is a possibility of nanotechnology being used to develop chemical weapons and because they will be able to develop the chemicals from the atom scale up, critics fear that chemical weapons developed from nano particles will be more dangerous than present chemical weapons.

Fear of UncertaintyNanotechnology is quite a new concept and some effects are time dependent so it's difficult for experts to predict the damage nanoparticles might do. There are concerns about how nano-particles may accumulate in nature. Could large amounts be ingested by fish? And if so, would if be harmful? Would the particles be passed along the food chain like DDT. Thresholds need to be determined. It's vital to find out how to remove or simply detect nanomaterials if they become problematic.

What happens to nanoparticles such as silver nanoparticles which are used quite a bit, for example in certain socks. In an experiment reported at the American Chemical Society meeting, washed seven brands of nanosilver socks and then tested the wastewater. All but one pair leaked silver. That silver, of course, ends up in our sewers, rivers and lakes. Results like this have strengthened the calls among scientists and environmentalists for a closer examination of nanoparticles and their effects on humans and the environment. You can find nanosilver in products from clothing and shoes to mattresses and pillows to appliances Considering how quickly the market is expanding worldwide, scientists doubt that current regulations are sufficient. They also point out the lack of regulations that specifically address nanoparticles and say that not enough is being spent on their health effects.


Assessing Risks of Nanomaterials

• Identify and characterize potential NM

hazards

• Assess potential exposure scenarios

• Evaluate toxicity

• Characterize risk and uncertainty

• Communicate about risks


Nanotoxicology is the field which studies potential health risks of nanomaterials. The extremely small size of nanomaterials means that they are much more readily taken up by the human body than larger sized particles. How these nanoparticles behave inside the organism is one of the significant issues that needs to be resolved.

The behavior of nanoparticles is a function of their size, shape and surface reactivity with the surrounding tissue.

The large number of variables influencing toxicity means that it is difficult to generalize about health risks associated with exposure to nanomaterials – each new nanomaterial must be assessed individually and all material properties must be taken into account. Health and environmental issues combine in the workplace of companies engaged in producing or using nanomaterials and in the laboratories engaged in nanoscience and nanotechnology research. It is safe to say that current workplace exposure standards for dusts cannot be applied directly to nanoparticle dusts.


Nanopollution is a generic name for all waste

generated by nanodevices or during the

nanomaterials manufacturing process.

Nanowaste is mainly the group of particles

that are released into the environment, or the

particles that are thrown away when still on

their products.


• People have encountered and ingested

nanometer-size particles since the

invention of fire -- soot is a good example.

So are air pollutants such as smog.


• Some of the new concerns center on metal-containing nano-materials such as titanium dioxide and zinc oxide. Compounds like these have always been used as sun blocks -- the thick solid-colored lotions you see on lifeguards' noses -- but once mixed into the lotions at a nano level, they turn translucent. Scientists fear that if the metallic atoms in these lotions get into the body, they'll create free radicals and undergo oxidation reactions, literally pulling cells apart in a fashion similar to the way alcohol consumption and cigarette smoking destroy cells.


• Another worry about special nano-material properties that could cause harm: Experiments are done with brain medications that use nano-materials to more easily target and enter trouble spots (drug delivery). But the easy maneuvering enabled by these tiny particles' size could prove a detriment. One study found that, when present in water, carbon structures called buckyballs slipped into the brains of large-mouth bass and killed cells. The study, however, was inconclusive and intended only to open the door for more research.


• Some science interest groups, also contend that while many outstanding questions remain, it's hardly time to sound the warning bells. We don't necessarily believe that there's a need to be alarmist -- we have been exposed to some of the materials for a while. But certainly there's enough novelty and enough new production going on that it's worth evaluating."

As it was for many other new technologies, it will take years before anyone knows for sure.


• Some nano-materials, such as fumed silica,

carbon black and titanium dioxide, have been

used for years but are just now being labeled

“nano”. New nano-materials usually have unique

structures, surface characteristics or other novel

chemical, physical and/or biological properties.

Nano-materials often have no value when

considered in isolation but when incorporated

into products or processes they “enable” the

product to exhibit some new quality or function


• The health and environmental risks from exposure to nano-materials are not yet clearly understood. Many nano-materials are formed from nanometer-scale particles (nanoparticles) that are initially produced as airborne particles or liquid suspensions. Exposure to these materials during manufacturing and use may occur by inhaling them, skin contact or ingesting them. Very little information is currently available on the most important exposure routes, exposure levels and toxicology. The information that does exist comes primarily from the study of ultra-fine particles (typically defined as particles smaller than 100 nanometers in diameter).


• Ultra-fine particles that do not dissolve are more

toxic, because smaller particles have a relatively

larger surface area. There are strong indications

that particle surface area and surface chemistry

are primarily responsible for the toxic effects

seen in cell cultures and test animals. Research

is underway to determine the extent to which

ultra-fine particles can penetrate the skin. There

is also concern that inhaled nanoparticles may

move from the lungs into other organs.


• Workers in nanotechnology-related industries have the potential to be exposed to uniquely engineered materials with novel sizes, shapes and physical and chemical properties at levels far exceeding ambient concentrations. Much research is still needed to understand the impact of these exposures on health and how best to devise appropriate exposure monitoring and control strategies. Until a clearer picture emerges, the limited evidence available would suggest caution when potential exposures to nano-materials may occur


• This new technology has tremendous potential across a number of areas in the economy and promise to improve our lives in different ways. Due to advancements in nanotechnology, its application in areas such as pollution reduction, new methods of energy production, and medical innovation is likely to have a positive effect on our lives in the near future. However, because the technologies are so new, they may have a hazardous impact on our health as well.

• The technology is very complicated and that there are potentially thousands of new substances that can be developed which, like chemicals, can have numerous different attributes. While we can quantify the potential for economic benefit and other benefits to society, presently science does not have the information necessary to quantify the potential for hazards or to develop a method for assessing those hazards.


• In most cases, nanoscale systems will alter in physical size upon interaction with an aqueous system. For example, it is very common for many nanostructures to adopt a different chemical form simply through relatively minor interactions; consequently, size is not a constant factor in biological interactions. Furthermore, the surface area can make up a sizeable fraction of these materials, and they can be derived to make many different biomedical systems. By changing surface coatings the nanomaterial toxicity can almost be completely altered.


• For example, changing the surface features of the materials can change a hydrophobic particle into a hydrophilic one. Hypothetically, surface coats could, for instance, make it possible to eat nanoscale mercury if it has the right surface coating, while it may be dangerous to eat nanoscale table salt if the surface coating was not correct. For this reason, the scientists’ typical view of toxicology, which is driven by the composition of an inorganic particle, may have to be modified for nanoscale materials, because the surface is going to affect different dimensions of environmental and health effects.


• INTERACTIONS WITH BIOLOGICAL SYSTEMS

• Chemists and engineers interested in creating biocompatible nanostructures need to understand their interactions with biological systems. It is suggested that the challenge that nanomaterials pose to environmental health is that they are not one material. It is difficult to generalize about them because, similar to polymers, they represent a very broad class of systems. Many engineered nanomaterials have precisely controlled internal structures, which are structures of perfect solids. Over a third of the atoms in a nanoparticle are at the surface, and these are extremely reactive systems, which in some cases can generate oxygen radicals however, nanoparticles can be tied up very tightly in covalent bonds and wrapped with a polymer.


• Because of the size of nanostructures, it is possible to manipulate the surface interface to allow for interactions with biological systems. With the correct coating particles below 50 nm can translocate into cells relatively easily and are able to interact with channels, enzymes, and other cellular proteins. Those particles above 100 nm, based primarily on size of the particles, have more difficulty. Through the interactions with cellular machinery, there is potential for medical uses, such as drug delivery and cellular imaging.


• While coating or covalently modifying the outer surfaces of nanomaterials eliminates the toxicity of most particles, questions remain about whether under environmental conditions—as opposed to laboratory conditions, the nanomaterials will still be benign. In a recent study, it was demonstrated that if surface-modified C60 materials were irradiated to UVA (i.e., ultraviolet radiation of 320–400 nm in wavelength) for 11 min or UVB (i.e. ultraviolet radiation of 290–320 nm) for 22 min, cytotoxicity returns. Additional research suggests that air exposure and nanoparticle dose are also important for cytotoxic effects. When cadmium selenide (CdSe) quantum dots in a liver culture model are exposed to air or ultraviolet light, hepatocyte viability decreases as assessed by mitochondrial activity of QD-treated cultures.


• So, while these nanomaterials may be

safe under laboratory conditions, a more

reliable or maybe environmentally relevant

endpoint is to weather these compounds

under environmental conditions are safe..


• Fullerenes and other nanomaterials can accumulate in the body, depending on the dosing route. For oral administration, 98 percent of fullerenes are eliminated within 48 hours via feces and urine. The 2 percent that is not eliminated is found throughout the rest of the body. Intravenous dosing is rapidly transported to the liver (73–92 percent), the spleen (up to 2 percent), lung (up to 5 percent), kidney (up to 3 percent), heart (approximately 1 percent), and the brain (approximately 0.84 percent) within 3 hours. After 1 week, 90 percent of intravenously administered fullerenes are still in the body.


• Nanoparticles, including C60, metal QDs, and TiO2 can be redox active (oxide reduction), which may lead to DNA cleavage, oxidative stress, and/or an inflammatory response. For example, C60 fullerenes, if exposed to light, can either make singlet oxygen or be electron donors to make super oxide radicals. The potential dilemma is that not only does the immune system use super oxide radicals to kill foreign toxicants; the super oxide radicals can cause hydroxyl radicals, which can lead to DNA cleavage. The good news is that the body has some ability to prevent the undesired DNA cleavage through super oxide dismutase, part of the antioxidant defense system.


• Toxicity of Carbon Nanotubes

• In a recent study, it was tried to investigate the toxicity of carbon nanotubes, which are approximately 1 nm by 1–5 µm as a singular particle. However, due to strong electrostatic potential, they rarely exist as individual discrete particles and agglomerate into nanoropes.

• Following instillation of the carbon nanotubes into the lung, the tissue was analyzed by looking at cell proliferation, histopathology, lung weights, etc. at 24 hours, 1 week, 1 month, and 3 months post instillation. Through this paradigm, the researchers would be able to determine the initial, transient reaction, but also ask whether the toxicity was sustained or progressive.


• Fifteen percent of the animals died within the first 12 hours due to high agglomeration from electrostatic attraction, which essentially coated the airways of these animals. This was not because of the toxicity of the material, but rather because the material coated their airways. Thus, these animals died from suffocation because of the unique properties of carbon nanotubes.


• The animals that survived the first 24 hours post instillation survived through the 3 months. Exposure to carbon nanotubes produced only a transient inflammatory response at 24 hours, but this was acute, with no inflammatory effects seen at 3 months. Since carbon nanotubes are used in the electronics field for diode, transistors, cellular-phone signal amplifier, and ion storage for batteries. Particles need to be thought of as having inherent toxicity, and being carriers for organic molecules and metals.


• Researchers performed exposure assessments in the workplace. The results suggested that the dust was less than 53 µg/m3, which was extremely low. Most of the nanotubes were aggregated into nanoropes, which may not be respirable. Scientists cannot assume that all nanomaterials are the same as their bulk counterparts, which suggests that materials will need to be tested on a case-by-case basis, a process that may be infeasible because of resource constraint. It was suggested that priorities for studying particles based on surface coating, surface charge, and particle aggregation will need to be made.

Singled Wall Carbon Nanotubes (SWCNT)

• Low concentration injection test

• Mice suffer from lung injuries after 7 to 90 days

• High concentration injection test

• More than 55% mortalities within less than 7 days

• Some mice have shown some sort of early tumour

in their lungs


Carbon nanotubes side effects:• Exposure to carbon Nano killed water fleas

• Carbon nanotube have caused extensive brain

damage and changed the physiological make-up of

fish

• Nano carbon can travel through a mother’s placenta

• Nano carbon can assist in the formation of free

radicals



How can inhaled nanoparticles affect health?

Inhaled particulate matter can be deposited throughout the human respiratory tract, and an important fraction of inhaled nanoparticles deposit in the lungs. Nanoparticles can potentially move from the lungs to other organs such as the brain, the liver, the spleen and possibly the foetus in pregnant women. Data on these pathways is extremely limited but the actual number of particles that move from one organ to another can be considerable, depending on exposure time. Even within the nanoscale, size is important and small nanoparticles have been shown to be more able to reach secondary organs than larger ones.


Another potential route of inhaled

nanoparticles within the body is the olfactory

nerve; nanoparticles may cross the mucous

membrane inside the nose and then reach

the brain through the olfactory nerve. Out of

three human studies, only one showed a

passage of inhaled nanoparticles into the

bloodstream.


Materials which by themselves are not very harmful could be toxic if they are inhaled in the form of nanoparticles.

The effects of inhaled nanoparticles in the body may include lung inflammation and heart problems. Studies in humans show that breathing in diesel soot causes a general inflammatory response and alters the system that regulates the involuntary functions in the cardiovascular system, such as control of heart rate.


What are the health implications of nanoparticles used as drug carriers?Nanoparticles can be used for drug delivery purposes, either as the drug itself or as the drug carrier. The product can be administered orally, applied onto the skin, or injected.

The objective of drug delivery with nanoparticles is either to get more of the drug to the target cells or to reduce the harmful effects of the free drug on other organs, or both. Nanoparticles used in this way have to circulate long distances evading the protection mechanisms of the body. To achieve this, nanoparticles are conceived to stick to cell membranes, get inside specific cells in the body or in tumours, and pass through cells. The surfaces of nanoparticles are sometimes also modified to avoid being recognized and eliminated by the immune system.

The use of nanoparticles as drug carriers may reduce the toxicity of the incorporated drug but it is sometimes difficult to distinguish the toxicity of the drug from that of the nanoparticle. Toxicity of gold nanoparticles, for instance, has been shown at high concentrations. In addition, nanoparticles trapped in the liver can affect the function of this organ.

Nanoparticles have the potential to cross the blood brain barrier, which makes them extremely useful as a way to deliver drugs directly to the brain. On the other hand, this is also a major drawback because nanoparticles used to carry drugs may be toxic to the brain.


How should harmful effects of nanoparticles be assessed?

Traditionally, doses are measured in terms of mass because the harmful effects of any substance depend on the mass of the substance to which the individual is exposed. However, for nanoparticles it is more reasonable to measure doses also in terms of number of particles and their surface area because these parameters further determine the interactions of nanoparticles with biological systems.

Because of the specific characteristics of nanoparticles, conventional toxicity tests may not be enough to detect all their possible harmful effects. Therefore, a series of specific tests was proposed to assess the toxicity of nanoparticles used in drug delivery systems. One mechanism of toxicity of nanoparticles is likely to be the induction of oxidative stress in cells and organs. Testing for interaction of nanoparticles with proteins and various cell types should be considered as part of the toxicological evaluation.


The interaction of nanoparticles with living systems is affected by nanoparticle properties as:

Size & Dimensions:

It is possible that nanoparticles with size of few nanometer reach inside biomolecules and cross cell membranes. One of the possible ways that nanoparticles may get into our body system is inhalation. Reports of inhaled nanoparticles reaching the blood and may reach other target sites such as the liver, heart or blood cells.

Because of their very small size, nanoparticles of any material have a much greater surface to volume ratio than larger particles. Therefore, relatively more molecules of the chemical are present on the surface. This may be one of the reasons why nanoparticles are generally more toxic than larger particles of the same composition.


Chemical Composition:

Nanoparticles may dissolve inside the body and their effects on organisms are the same as the effects of the composed chemicals.

The toxicity of nanoparticles depends on their chemical composition, but also on the composition of any chemicals adsorbed onto their surfaces.

(The surfaces of nanoparticles can be modified to make them less harmful to health.)

Dose:

The ability of nanoparticles to spread within the body.


Solubility:

The major emerging issue to be discussed in the context of the biological interactions of nanoparticles is related to those particles with little or no solubility, or being non-degradable at the locality where accumulation is observed. There remain many unknown details about the interaction of nanoparticles and biological systems.

Some nanoparticles dissolve easily and their effects on living organisms are the same as the effects of the chemical they are made of. However, other nanoparticles do not degrade or dissolve readily. Instead, they may accumulate in biological systems and persist for a long time, a source of concerns.


Surface Characteristics

Depend on their surface structures, their

chemistry, and their energy, nanoparticles will

adsorb some biomolecules once they are in touch

with tissues or body fluids. In practice, the surface

of nanoparticles may be modified or functionalized

to facilitate the interactions between nanoparticles

and surrounding biomolecules.


Shape:

Although there is little definitive evidence, the

health effects of nanoparticles are likely to depend

also on their shape. A significant example is

nanotubes, which may be of a few nanometres in

diameter but with a length that could be several

micrometres. A recent study showed a high toxicity

of carbon nanotubes which seemed to produce

harmful effects by an entirely new mechanism,

different from the normal model of toxic dusts.

• Composition and Structure

• Solubility

• Reactivity

• Surface Chemistry

• Aggregation Potential

• Surface Area

• Shape

• Density

• Particle Size

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Key Factors:

In Summary

• Limited number of nanomaterials have been evaluated to date

• Toxicological aspects and assessment of nano materials are just starting.

• Insoluble nanoparticles are the greatest cause of concern. Several studies have shown that some of them can pass through the various protective barriers of the living organisms. The inhaled nanoparticles can end up in the bloodstream after passing through respiratory or gastrointestinal protective mechanism. They may penetrate nerves and eventually brain.

• Most toxicity is linked to nanoparticles large surface area.

• Many substance like TiO2 recognized as non-toxic material becomes toxic on nano scales.

In Summary

• Still due to the small number of studies, the short exposure period, the different composition of the nanoparticles tested, and other factors, the toxicological data remains insufficient.

• Toxic dose is usually measured in mass unit however, in case of nanoparticles due to large numbers and their large surfaces this unit is not appropriate anymore and should be measure in term of numbers and the surface of any given mass.

• Discouraging the aggregation and agglomerate among nanoparticles, usually they are coated by specific chemical which may change the toxicity of the nanostructures.

In Summary

• Current developments in nanotechnology are increasing at such a rapid pace that it is a challenge for any government to stay up-to-date with progress. Nanotechnology has received considerable attention from scientific communities and governments worldwide. The United States, France, Japan, and Canada have centers and government agencies where they make assessments of the potential risks and benefits to human health posed by nanotechnology

In Summary

• Nanotechnology is one of the priorities for the Canadian government. Canada wants to be a world leader in developing and applying twenty-first century technologies such as biotechnology, environmental technology, information and communication technologies, health technologies, and nanotechnology.

• The Canadian government also has realized that it is time to break down barriers between research disciplines and to foster multidisciplinary approach. In this spirit, the government in Canada no longer funds one lab working on one item in isolation and favors a multi-faculty approach, where people with different backgrounds (physicists, biologists, and chemists) can work together on nanotechnology issues.

In Summary

• The Canadian government sees its responsibility in terms of ensuring that their society will be able to interact with new technologies, contribute to them, and manage them as they develop. In order to do so, the Canadian government conducts discussions with many departments and agencies and holds workshops that bring people together and allow them to take leads on different issues. Hopefully, the Canadian government plans to continue this interdepartmental, interdisciplinary approach.

In Summary

• Some basic strategies approached by the government are:

• Encouraging basic research to achieve fundamental knowledge and understanding of nanoscale phenomena and processes.

• Promoting applied research in specific “grand challenge” areas to accelerate transition of scientific discovery into innovative technologies.

• Providing mechanisms to facilitate transfer of technology into commercial applications and to support basic and applied research.

• Establishing research programs to understand the social, ethical, health, and environmental implications of the technology.

In Quebec

• IRSST (“Institute de recherche Robert

Sauve en sante et en securite du travail”)

supporting researches on Safety and

health effects of nanostructures.

Documents

Nanotechnology and Prime Materials - Encsusers.encs.concordia.ca/~mojtaba/elec6271/Nano-from-different-angle-2017.pdf•Nano water purifiers. •inexpensive energy generation. •Pollution