SYN THE SIS OF FLUORAPATITE NANOPOWDERS BY ASURFACTANT-AS SISTED MI CRO WAVE METHOD UN DER

ISO THER MAL CON DI TIONS

by

Vojislav Dj. STANI] 1*, Borivoj K. ADNADJEVI] 2,Suzana I. DIMITRIJEVI] 3, Slavko D. DIMOVI] 1, Miodrag N. MITRI] 1,

Bojana B. ZMEJKOVSKI 4, and Slavko SMILJANI] 5

1 Vin~a In sti tute of Nu clear Sci ences, Uni ver sity of Bel grade, Bel grade, Ser bia2 Fac ulty of Phys i cal Chem is try, Uni ver sity of Bel grade, Bel grade, Ser bia

3 Fac ulty of Tech nol ogy and Met al lurgy, Uni ver sity of Bel grade, Bel grade, Ser bia4 De part ment of Chem is try, In sti tute of Chem is try, Tech nol ogy and Met al lurgy,

Uni ver sity of Bel grade, Bel grade, Ser bia5 Fac ulty of Tech nol ogy, Uni ver sity of East Sarajevo, Re pub lic of Srpska, Bosnia and Herzegovina

Sci en tific pa perhttp://doi.org/10.2298/NTRP1802180S

Fluorapatite nanopowders with dif fer ent amounts of flu o ride ions were pre pared us ing thesurfactant-as sisted mi cro wave method un der iso ther mal con di tions. Mi cro wave ir ra di a tionwas ap plied for the rapid for ma tion of crys tals. A micellar so lu tion of polyoxyethylene (23)lauryl ether was used as a reg u la tor of nu cle ation and crys tal growth. Char ac ter iza tion stud iesfrom X-ray dif frac tion, field-emis sion scaning elec tron mi cros copy and Fou rier-trans form in -fra red spec tra showed that crys tals have an ap a tite struc ture and par ti cles of all sam ples arenano size, with an av er age length of 50 nm and about 15-25 nm in di am e ter. Antimicrobialstud ies have dem on strated that syn the sized fluorapatite nanopowders ex hibit ac tiv ity againsttested patho gens: Esch e richia coli, Staph y lo coc cus aureus and Candida albicans. Ac tiv ity in -creased with the amount of flu o ride ions. The syn the sized fluorapatite nanomaterials areprom is ing as ma te ri als in en vi ron men tal pro tec tion and med i cine for or tho pe dics and den talres to ra tions.

Key words: fluorapatite, mi cro wave pro cess ing, nanopowder, en vi ron men tal pro tec tion

INTRODUCTION

Syn thetic ap a tite ma te ri als have been an in dis -pens able com po nent of var i ous ap pli ca tions in en vi ron -men tal pro tec tion and med i cine for or tho pe dics andden tal res to ra tions [1-3]. The toxic and ra dio ac tiveheavy met als are one of the most dan ger ous toxic con -tam i nants in the en vi ron ment, es pe cially in ground wa -ter and soil. The fate of heavy met als in the en vi ron ment de pends mainly on their in ter ac tion with min er als. Thesta bil ity of the fi nal prod uct of this in ter ac tion rep re -sents a key fac tor, which de ter mines mo bil ity and bi o -log i cal avail abil ity of heavy metal pol lut ants in the en -vi ron ment. Ap a tite was se lected as an ideal ma te rial forlong-term con tain ment of heavy met als, which have ahigh sorp tion ca pac ity for these met als, low wa ter sol u -bil ity, high sta bil ity un der re duc ing and ox i diz ing con -di tions, low cost, and avail abil ity. The apatites in ves ti -gated in clude syn thetic hydroxyapatite (HAP;

Ca10(PO4)6(OH)2) and fluoroapatite (FAP; Ca10

(PO4)6F2), apatites of bi o log i cal or i gin and nat u rallyoc cur ring ap a tite min er als [4-7]. Fluoroapatite, in com -par i son to pure hydroxyapatite and other ap a tite ma te ri -als, has higher physico-chem i cal sta bil ity, such as an in -creased re sis tance to dis so lu tion by acid [8]. It has ahigh af fin ity for ura nium and other radionuclides [9].Al pha ra di a tion, re sult ing from the de cay ofradionuclides, found in the crys tal line struc ture of ap a -tite ma te ri als can in duce crys tal line to amor phous trans -for ma tion [10-12]. Fluorapatite ma te ri als showed ra di -a tion-dam age re sis tance at tem per a tures above 70 °C,mak ing them very prom is ing ma te ri als for nu clearwaste stor age [13]. Biomaterials based on fluoroapatitehave been very prom is ing be cause of their crys tal lo -graphic sim i lar i ties to the nat u ral in or ganic com po nentof bone (hydroxyapatite). In vi tro and in vivo stud ieshave shown that syn thetic fluoroapatite is a pos si ble re -place ment for bone re pair due to its biocompatibility,bioactivity, and osteo- con duc tive prop er ties [14]. Im -plant-as so ci ated in fec tions pres ent sig nif i cant sur gi cal

V. Dj. Stani}, et al.: Syn the sis of Fluorapatite Nanopowders by a Surfactant- ...180 Nu clear Tech nol ogy & Ra di a tion Pro tec tion: Year 2018, Vol. 33, No. 2, pp. 180-187

* Cor re spond ing au thor; e-mail: voyo@vin.bg.ac.rs

prob lems and usu ally re quire re moval [15]. To solve the prob lem of im plant re lated in fec tions, the use of boneim plants which in clude antimicrobial agents such as an -ti bi ot ics, flu o ride and biocides metal ions is pro posed[16-18]. Flu o ride ions play an im por tant role in the pre -ven tion and con trol of den tal car ies. Fluorapatite ma te -ri als showed po ten tial an ti bac te rial ac tiv ity but not thebiocidal ef fect [16].

The many ap pli ca tions of fluoroapatite ma te ri als mainly de pend on the chem i cal com po si tion, shape,mor phol ogy, and size of ap a tite par ti cles. There fore,var i ous syn the sis meth ods of fluorapatite have beende vel oped in re cent years: neu tral iza tion [16], sol-gel[19], surfactant-as sisted [20], mechanochemical syn -the sis [21], mi cro wave [22] and flame spray py rol y sis[23]. Most of these meth ods re quire time con sum ingpro ce dures and ob tain mac ro scopic par ti cles.

Mi cro wave heat ing is a widely ac cepted,non-con ven tional en ergy source for in or ganic, or -ganic syn the sis, and dif fer ent physicochemical pro -cesses, such as sintering, nu cle ation and crys tal li za -tion, ad sorp tion, and so forth [24, 25]. The ef fect ofmi cro wave ir ra di a tion on the ki net ics of chem i cal re -ac tions is ex plained by ther mal ef fects, such as over -heat ing, hot-spots, se lec tive heat ing or as a con se -quence of spe cific mi cro wave ef fects. The mainad van tages of us ing the mi cro wave method, rel a tive to con ven tional heat ing meth ods in chem i cal syn the sis,are rapid vol u met ric heat ing, higher re ac tion rate,shorter re ac tion time, se lec tiv ity, and higher yield. The surfactant-as sisted method is very prom is ing for syn -the sis of ap a tite nanoparticles [20]. Surfactant prop er -ties, in par tic u lar the po lar ity of the heads as well as itsquan tity in the so lu tion, can af fect the crys tal li za tionpro cess, the chem i cal com po si tion, size and mor phol -

ogy of ap a tite par ti cles. Sev eral stud ies have shownthat sur fac tants have an im pact on the mor phol ogy and size of ap a tite par ti cles ob tained by the mi cro wavemethod [26, 27]. Gopi et al. [26] re ported the syn the sis of hy dro- xyapatite nanospheres by us ing the mi cro -wave heat ing method and hexadecyltrimethy-lammonium bro mide (CTAB) as a tem plate. Arami etal. [27] re ported the syn the sis of hydroxyapatitenanostrips with an av er age width of 10 nm and lengthof 55 nm us ing CTAB as the surfactant.

In this work, fluorapatite (Ca10(PO4)6Fx(OH)2-x,0 £ x £ 2) pow ders with dif fer ent flu o ride con cen tra -tions were syn the sized by the surfactant-as sisted mi -cro wave method. The main rea son for us ing thesurfactant-as sisted mi cro wave method is the pos si bil -ity of pre par ing nanoprod ucts in a short time from rel a -tively in ex pen sive chem i cals, and thereby mak ing itsuit able for an in dus trial pro duc tion. The antimi cro -bial ac tiv ity of fluorapatite sam ples was tested againstdif fer ent patho gens: Staph y lo coc cus aureus (S.aureus), Esch e richia coli (E. coli), and Candidaalbicans (C. albicans) was eval u ated in vi tro.

MATERIALS AND METHODS

Preparation of the materials

The start ing ma te ri als were Ca(CH3

COO)2xH2O (AppliChem), (NH4)2HPO4 (Merck),polyoxyethylene (23) lauryl(ether) (Brij 35; AlfaAesar), NaF (VWR) and NH4OH (Merck) of proanalysis grade of pu rity. The mi cro wave as sisted re ac -tions were con ducted us ing a mi cro wave re ac tor (Dis -cover, CEM Corp., Matthews, N. C., USA) sup pliedwith a pro grammed tem per a ture con trol sys tem. Allthe re ac tions were car ried out in the mi cro wave fieldof 2.45 GHz, main tain ing the de sired tem per a tures at60 °C.

The first so lu tion was pre pared by mix ing 50 mL

of 0.1 M Brij 35 and 100 mL of Ca(CH3COO)2 (0.11 M).

The sec ond so lu tion of 50 mL (NH4)2HPO4 (0.13 M) and

NaF (0.01 M; 0,.02 M; 0.03 M or 0.04 M) was dropped

into the first so lu tion. The pH of both so lu tions was

main tained at 10 by the NH4OH so lu tion be fore mix ing.

The syn the sis pro cess in a mi cro wave field lasted 15

min utes with con stant stir ring. The pre cip i tate thus ob -

tained was fil tered by a vac uum fil tra tion pro cess. The

pre cip i tate was washed with eth a nol and wa ter to re move

the ex cess of Brij 35, and dried at 105 ºC and pul ver ized

into a pow der.

Characterization of synthesizedapatite samples

The X-ray dif frac tion (XRD) stud ies of theapatites were per formed us ing a Philips PW 1050diffractometer, us ing CuK1.2 Ni-fil tered ra di a tion.The dif fracted X-rays were col lected over a 2q range20-80° us ing a step width of 0.02° and mea sured for 1 s per step. Lat tice pa ram e ters a, b, and c of the ap a titehex ag o nal unit cell and av er age crys tal lite size werede ter mined us ing the Pow der Cell 2.4 pro gram.

The Fou rier-trans form in fra red (FTIR) spec traof syn the sized ap a tite sam ples, were re corded on aNicolet 6700 FTIR spectrophotometer (Thermo Sci -en tific) us ing the ATR tech nique, in a fre quency in ter -val of 4000-400 cm–1.

The mor phol ogy of the ob tained pow ders wasstud ied by field-emis sion scan ning elec tron mi cros -copy (FESEM) TESCAN Mira3 XMU at 20 kV. Priorto the SEM anal y sis, the pow der sam ples were coatedwith an Au-Pd al loy us ing a spat ter coater.

The semi-quan ti ta tive chem i cal anal y sis of thesam ples was ana lysed us ing an en ergy dispersivespec trom e ter (EDS) with a SiLi X-ray de tec tor (Ox -ford In stru ments, UK) con nected to a scan ning elec -tron mi cro scope and a com puter multi-chan nel an a -lyzer. The mea sure ments were per formed to de tectcalcium, phosphorus, and fluor.

The com bined mea sure ments un cer tainty of theex per i men tal pro ce dures was less than 5 % [28-30].

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In vitro antimicrobial activity

Antimicrobial ac tiv i ties of sam ples were in ves ti -gated, by a mod i fied liq uid chal lenge method, [31]against a gram-neg a tive bac te rial strain E. coli (ATCC25922), gram-pos i tive bac te rium S. aureus (ATCC25923) and yeast C. albicans (ATCC 24433). Prior toob tain ing inoculum, bac te ria were cul ti vated on nu tri -tion agar No. 8 and yeast on malt ex tract agar No. 37slants (LabM, U. K). The in cu ba tion time for bac te ria was 24 h at 37 °C and for yeast 48 h at 28 °C.

The 0.01 g of an ap pro pri ate ap a tite sam ple waschal lenged to 1 mL of an in oc u lated buf fered sa line so -lu tion con tain ing about 2.1×106 cfumL–1 (S. aureus),7.54×106 cfumL–1 (E. Coli) and 2×106 cfumL–1 (C.albicans). Af ter one hour of in cu ba tion at 37 °C in awa ter bath shaker, 9 mL of sa line was added and thesus pen sion was vig or ously vortexed for 3 min to sep a -rate the cells since they tend to ad sorb to the par ti cles[16]. Aliquots of 1 mL were taken as sam ples for fur -ther di lu tion with sa line and vi a ble cell de ter mi na tionby seed ing in agar plate Petri dishes with a cor re -spond ing me dium. The formed col ony units werecounted af ter in cu ba tion in a ther mo stat un der ap pro -pri ate con di tions.

The per cent age of vi a ble cell re duc tion (R %)was cal cu lated us ing the eq. (1).

R C C C[%] ( ) /= × -100 0 0 (1)

where C0 is the av er age num ber of strain col o nies ofthe con trol, and C – the cor re spond ing num ber of col o -nies of chal lenged ap a tite sam ples at the same pre de -ter mined time.

RESULTS

Characterization of apatitenanocrystals

The XRD pat terns of syn the sized ap a tite sam -ples are pre sented in fig. 1. The po si tions of its X-raydif frac tion peaks were in ac cor dance with ASTM datafor hydroxyapatite (Card 9-0432) and fluorapatite(Card 15-0876). The lat tice pa ram e ters, crys tal lite size and the frac tion of the crys tal line phase of all sam plesare pre sented in tab. 1.

The re sults of EDS anal y sis for cal cium, phos -pho rus, and fluor of all sam ples are shown in tab. 2.

The FTIR spec tra of the sam ples are shown infig. 2. The spec tra show the char ac ter is tic bands forphos phate and hydroxyl groups and ab sorbed wa ter.The dom i nant bands that ap pear at 1043-1018 cm–1

and the small band at 961 cm–1 be long to the asym met -ric stretch vi bra tion of PO4

3- groups, while the bands at 563-550 cm–1 orig i nate from the stretch ing sym met ricvi bra tions. The bands at 451-432 cm–1 cor re spond to asym met ri cal vi bra tion from PO4

3- groups. The

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Figure. 1 XRD pat terns of hydroxyapatite andfluorapatites with dif fer ent con tents of flu o ride ions

Table 1. Unit cell parameters and crystallite sizes (Xs) ofall synthesized apatite samples

Sample a c Xs

HAP 9.43484 6.88009 17.5

FHAP1 9.42393 6.88472 13.5

FHAP2 9.39608 6.88162 15.7

FHAP3 9.38626 6.88482 17.5

FAP 9.38450 6.88427 19.9

Table 2. The results of EDS analyses of hydroxyapatiteand fluorapatite samples (*atomic ratio [%])

Sample Ca* P*Ca/P

F*Nominal Measured

HAP 14.84 9.76 1.67 1.52 0

HFAP1 15.87 9.44 1.67 1.68 0.53

FHAP2 15.76 9.22 1.67 1.71 1.84

FHAP3 17.21 9.88 1.67 1.74 2.80

FAP 18.29 9.66 1.67 1.89 3.10

Fig ure 2. FTIR trans mit tance spec tra of syn the sizedsam ples: hydroxyapatite and fluorapatites withdif fer ent con tent of flu o ride ions

FHAP1, FHAP2, and FHAP3 sam ples con tain an ad -di tional band orig i nat ing from the PO4

3- groups atabout 991 cm–1. The weak bands at about 1430 cm–1

and 870 cm–1 in di cate the pres ence of car bon ate ionsin sam ples. The broad ab sorp tion band at 2500-3700cm–1 and weak at 1640 cm–1 are as signed to the ad -sorbed wa ter. The weak band of the hydroxyl group lo -cated ap prox i mately at 3572 cm–1 is eas ily vis i ble inthe HAP sam ple. FESEM mi cro graphs of the HAP and FHAP sam ples are pre sented in fig. 3. Mor phol -ogy of the syn the sized sam ples were was sim i lar. Thepar ti cles have a nano-size char ac ter and an ir reg u larrod-like mor phol ogy. The av er age lenghtlength ofpar ti cles in all sam ples is about 50 nm in lenghtlengthand they have are about 15-25 nm in di am e ter.

The results of antimicrobialactivity determination

The re sults of the antimicrobial tests of thefluorapatite sam ples against mi crobes are shown infig. 4. The antimicrobial ef fect dem on strates that allap a tite sam ples show vi a ble cell re duc tion of mi cro -bial spe cies. Antimicrobial ac tiv ity of fluorapatite ma -te ri als is a func tion of quan ti ties of flu o ride ions andthe types of mi crobes.

DISCUSSION

One of the most prom is ing meth ods for the syn -the sis of ap a tite ma te ri als is the mi cro wave method.Mi cro wave ra di a tion cre ates a heat ing so lu tion whichcan af fect the sta bil ity of the surfactant micellar so lu -tion. In this work iso ther mal con di tions (T = 60 ºC) areused to en sure the sta bil ity of the micellar so lu tions.The used con cen tra tion of Brij 35 (0.025 M) is higherthan the crit i cal micellar con cen tra tion (CMC) of0.048 mM at 25 ºC and 0.034 mM at 50 ºC [32, 33].Schwarzenbacher et al. [34] re ported that an aque ousso lu tion of Brij 35 (to 30 % w/w) at 60 ºC is micellarwhile at higher ra tios leads to the for ma tion of an iso -tro pic surfactant liq uid.

The XRD pat terns (fig. 1) of syn the sized sam -ples are sim i lar, dif frac tion peaks were broad, in di cat -ing that the ob tained prod ucts have low crystallinityand that the crys tal lites were nanosized. There are noother char ac ter is tic peaks of im pu ri ties, such as CaOand other cal cium phos phates. Crys tal lo graphic sim i -lar ity of ap a tite sam ples come from the same hex ag o -nal lat tice struc ture of space group P63/m, with slightdif fer ences. The in cor po ra tion of flu o ride ions into the ap a tite struc ture causes a de crease in the lat tice pa ram -e ter (a) (tab. 1). A sig nif i cant in the lat tice pa ram e ter(a) was ob served in pre vi ous stud ies [16, 19]. Changes in the lat tice pa ram e ter (a) are the re sult of dif fer encesin size, struc tures and phys i cal prop er ties of F– (0.136

nm) and OH– (0.14 nm) ions. Other ions, es pe ciallycar bon ate ions, in flu ence the val ues of lat tice pa ram e -ters, which lead to a con trac tion in the a-axis di men -sion and ex pan sion in the c-axis di men sion. The in cor -po ra tion of car bon ate ions can also re sult in smallercrys tals and amor phous prod ucts. Ac cord ing to FTIRanal y sis (fig. 2) car bon ate ions are pres ent in all sam -ples.

EDS el e men tal anal y sis shows that all [Ca]/[P]ra tios in the sam ples are sim i lar to the amount of thestart ing ma te rial (tab. 2). Ac cord ing to the ob tained re -sults it can be as sumed that flu o ride ions are al mostcom pletely in cor po rated into the ap a tite struc ture. The ex ist ing dif fer ences can be re lated to the pres ent tracesof car bon ate ions.

FTIR spec tra of all ap a tite sam ples (fig. 2) dis -played typ i cal absorbance bands, which are in agree -ment with lit er a ture data [35]. The pres ence of weakbands at 870 cm–1 and 1430 cm–1, in di cate to a B-type sub sti tu tion within some CO3

2- groups in PO43- sites of

the ap a tite lat tice. The in ten sity of these bands can in -di cate that a small amount of car bon ate ions is in cor -po rated into ap a tite sam ples. Nat u ral fluoroapatiteshave a greater ca pac ity to re tain ura nium and a big geracidic sol u bil ity with an in crease in the amount of car -bon ate ions [36, 37].

The mor phol ogy and size of ap a tite par ti cles isin flu enced by many fac tors such as the type and con -cen tra tion of the pre cur sors, con di tions of syn the sis(pH, tem per a ture) and op tion ally, a va ri ety of or ganicsub stances such as sur fac tants, dur ing the syn the sispro cess. Silva et al. [38] re ported that fluorapatitecrys tals are ob tained from an aque ous so lu tion in thecourse of 3 hours with a rod-like rect an gu lar shape.Fluorhydroxyapatite nanorod par ti cles with a rel a -tively uni form rod-like mor phol ogy were ob tained bya pre cip i ta tion method in the precencepresence of anon-ionic surfactant [poly(oxyethylene)sorbitanmonooleate] (Tween 80) and ac e tate ions [20]. Themorphologies of syn the sized ap a tite sam ples (fig. 3)are sim i lar to the mor phol ogy found in hydroxyapatitepow ders pre pared un der mi cro wave ir ra di a -tion/iridation? in the pres ence of so dium lauryl ethersul fate or alkylbenzene sulfonate [39]. A com par i sonof the av er age par ti cle size and the mean crys tal litesize (tab. 1), de ter mined from the X-ray dif frac tiondata, in di cates a polycrystalline na ture of the pow derpar ti cles. Ac cord ing to the FESEM mi cro graphs it canbe con cluded that the amount of flu o ride ions does notsig nif i cantly in flu ence on the size and mor phol ogy ofpar ti cles. Nanosized ap a tite dis played a fast and highsorp tion ca pac ity of heavy metal ions [40, 41]. This isvery im por tant for rapid re moval of heavy metal ionsand the pre ven tion of en vi ron men tal threats.

The antimicrobial prop er ties of syn the sizedfluorapatite pow ders as prom is ing biomaterials for use in the re con struc tion of bone de fects would be of greatrel e vance. In this study, antimicrobial ac tiv i ties of the

V. Dj. Stani}, et al.: Syn the sis of Fluorapatite Nanopowders by a Surfactant- ...Nu clear Tech nol ogy & Ra di a tion Pro tec tion: Year 2018, Vol. 33, No. 2, pp. 180-187 183

V. Dj. Stani}, et al.: Syn the sis of Fluorapatite Nanopowders by a Surfactant- ...184 Nu clear Tech nol ogy & Ra di a tion Pro tec tion: Year 2018, Vol. 33, No. 2, pp. 180-187

Fig ure 3. FESEM im ages of syn the sized sam ples; HAP (a), FHAP1 (b), FHAP2 (c), FHAP3 (d), and FAP (e)

fluorapatite sam ples were tested against S. aureus, E.coli and C. albicans, be cause those spe cies have beenin volved in bone im plants-re lated in fec tions [42]. S.aureus ap pears as the main caus ative agent. In fec tionsby E. coli and C. albicans as the main causes are rare.

Ac cord ing to the re sults of the antimicrobial as -say (fig. 4), the hydroxyapatite sam ple showed a re -duc tion in the vi a ble cell num ber of in ves ti gated spe -cies as a re sult of their ad he sion to the sur face of thepar ti cles. Hydroxyapatite biomaterials do not haveantimicrobial prop er ties and mi crobes can col o nizetheir sur face. Flu o ride ions de crease ad he sion prop er -ties of some car ci no genic patho gen bac te ria on ahydroxyapatite sur face [43]. The per cent age of mi cro -bial re duc tion af ter the treat ment with the fluorapatitesyn the sized sam ples is higher and in creases with theamount of flu o ride (fig. 4). Among the tested mi cro -bial spe cies, gram-neg a tive bac te ria E. coli are themost sus cep ti ble to the fluorapatite ma te ri als. The E.coli bac te rium ad heres more weakly to the sur faces ofthe fluorapatite ce ment than that on the nat u ral enamel, in di cat ing that fluorapatite ce ment could in hibit bac te -ria at tach ment and have antimicrobial prop er ties [44].Ge et al. [45] re ported that fluorhydro- xyapatite coat -ings showed an ti bac te rial ac tiv i ties against Staph y lo -coc cus aureus and Esch e richia coli in phos phate buf -fered sa line (pH 7.4). We pre vi ously, re ported that theK. pneumoniae (gram-neg a tive) bac te ria showedgreater sen si tiv ity than S. aureus to pure and sil -ver-doped fluorapatite ma te ri als [17]. C. albicansshowed a slightly higher sen si tiv ity than S. aureus to -ward fluorapatite ma te ri als (fig. 4). A pre vi ous studyhas shown that the use of flu o ride proved to be a re duc -ing agent for the growth and ac tiv ity of C. albicans[46]. The mech a nism of antimicrobial ac tions of flu o -ride ions is com plex and in com pletely un der stood. Wesup pose that the antimicrobial ef fect of fluorapatitesam ples is mainly based on flu o ride ions re leased inthe PBS so lu tion. The flu o ride ions can be re leased

from fluorapatite par ti cles in an al ka line me dium byion ex change with OH- ions [47].

CONCLUSION

Fluorapatite pow ders with dif fer ent flu o ridecon cen tra tions were syn the sized in the micellar so lu -tion of the surfactant Brij 35 un der mi cro wave ra di a -tion and iso ther mal con di tions, T = 60 ºC. The anal y sisof XRD, FTIR, and SEM showed that par ti cles offluorapatite sam ples are of nanosize and ho mog e nousin com po si tion. The syn the sized fluorapatite sam plesshowed antimicrobial ac tiv ity against S. aureus, E.coli and C. albicans. The re sults of this study in di catethat syn the sized fluorapatite nanomaterials can becon sid ered as a po ten tial sorbent for toxic and ra dio ac -tive heavy met als ions and antimicrobial biomaterialsin or tho pe dics and den tistry.

ACKNOWLEDGEMENT

This work was sup ported by the Min is try of Ed -u ca tion, Sci ence and Tech no log i cal De vel op ment ofthe Re pub lic of Ser bia (Pro ject No. III 43009).

AUTHORS' CONTRIBUTIONS

The syn the sis of fluorapatite ma te ri als was car -ried out by V. Dj. Stani} and B. K. Adnadjevi}. Thephys i cal and chem i cal char ac ter iza tion of syn the sizedma te ri als was done by S. I. Dimitrijevi}, S. D. Di-movi}, M. N. Mitri}, B. B. Zmejkovski, and S. Smi-ljani}. All au thors dis cussed the re sults and com -mented on the manu script.

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Re ceived on De cem ber 5, 2017Ac cepted on Feb ru ary 12, 2018

V. Dj. Stani}, et al.: Syn the sis of Fluorapatite Nanopowders by a Surfactant- ...Nu clear Tech nol ogy & Ra di a tion Pro tec tion: Year 2018, Vol. 33, No. 2, pp. 180-187 187

Vojislav \. STANI], Borivoj K. ADNA\EVI], Suzana I. DIMITRIJEVI],Slavko D. DIMOVI], Miodrag N. MITRI], Bojana B. ZMEJKOVSKI,

Slavko SMIQANI]

SINTEZA FLUOROPATITNIH NANOPRAHOVA POMO]U MIKROTALASNE METODE U PRISUSTVU TENZIDA POD IZOTERMALNIM USLOVIMA

Fluoroapatitni nanoprahovi sa razli~itim koli~inam fluoridnih jona napravqeni su pomo}u mikrotalasne metode u prisustvu tenzida pod izotermalnim uslovima. Micelarni rastvorpolioksietilen (23) lauril etera kori{}en je kao reg u la tor nukleacije i rasta kristala. Ka-rakterizacione studije: rendgenostrukturna analiza, emisiona skeniraju}a elektronska mikro-skopija i Furije-transformisani infracrveni spektri, pokazale su da kristali imaju apatitnustrukturu i da su ~estice svih uzoraka nanoveli~ine, sa sredwom du`inom oko 50 nm i oko 15-25 nm upre~niku. Antimikrobne studije pokazale su da sintetisani fluoroapatitni nanoprahovi ispo-qavaju aktivnost protiv testiranih patogena: Esch e richia coli, Staph y lo coc cus aureus i Candida albicans. Aktivnost se pove}ala sa koli~inom fluoridnih jona. Sintetisani fluoroapatitni nanoprahovisu obe}avaju}i materijali u za{titi `ivotne sredine i u medicini za ortopedske i zubne re-stauracije.

Kqu~ne re~i: fluoroapatit, mikrotalasna obrada, nanoprah, za{tita `ivotne sredine