Tgp chi Cong nghe Sinh hgc 12(1): 157-163,2014
N G H I E N C i r u A N H H I T O N G C U A K I C H T H U * 6 c H ^ T N A N O C H I T O S A N L E N H O A T T I N H D O I K H A N G M Q T S O C H U N G V I S I N H V A T
Nguyin Thi Kim Ciic', Tr4n Thi Kim Dung^ Pham Vi^t Cudng''^
Vi^n Hoa sinh bien, Vien Hdn ldm Khoa hgc vd Cong nghe Viet Nam
Vi4n Nghien ciru Khoa hgc mien Trung, Vien Hdn ldm Khoa hgc vd Cong nghe Viet Nam N g a y n h a n b a i : 27.12.2013
N g a y n h a n d a n g : 23.3.2014 TOM TAT
Chitosan duac su dung rgng rai trong nhilu llnh vuc khac nhau do ban chit tuong thi'ch sinh hgc, khong ddc, khang khuin, khang nam va chong oxy hoa, Cac hat nanochitosan khong nhimg vln giC dugc cac tinh chit cua chitosan ma con c6 nhihig die tinh dac biet khac do kich thudc nho va dien tich b6 mat idn. Da co mot s6 bdo cao ve hoat tinh doi khang vi sinh vat cua nanochitosan nhung co rat it bao cao ve tuong quan giiia kich thudc hat tao thanh va ho^t tinh ciia chiing. Chung toi da tao dugc 3 loai hat nanochitosan vdi kich thudc khac nhau bang phuong phap lien ket ion khi thay ddi toe do va thdi gian khuay hon hop chitosan • tri polyphosphate (TPP). V$n t6c khuay 4000 v/ph trong 2 gid, cac hat nanochitosan tao thanh co kich thudc khoang 1000 nm, tSng thdi gian len 4 gid, kich thudc cac hat giara xuong mgl nita, con khoang 500 nm. Tang toe do khuay len 8000 v/ph trong 1 gid da tao dugc hat nanochitosan kich thudc khoang 100 nm. Nanochitosan irc che smh tnrdng cua c^c chung vi khuan va vi nam nghien ciru manh hon so vdi dung dich chitosan. Hat nanochitosan co kich thudc nho hon the hien hoat llnh doi khang tot hon so vdi cac hat co kich thudc ldn hen Chiing vi khuan Gram (-) Listonella damsela man cam vdi cac loai hat nanochitosan hem so vdi cac chiing vt khuan Gram (+) (Bacillus va Micrococcus). Trong 3 chung vi nam nghien cim, chung Aspergillus awamori c6 kha nSng khang l^i tac dpng ciia dung dich chitosan cung nhu cac hat nanochitosan tao thanh.
Tir khda • Doi khdng vl sinh vdt. lien kit ion. nanochitosan, vi khudn. vi ndm
M d D A U
Chitosan ngay cang duoc su dung rpng rai trong nhifeu ITnh vyc khac nhau dudi nhieu hinh thai khac nhau do ban chat tuong thich sinh hpc va khdng dpc.
Ngoai ra, chitosan cdn dupc chirng minh co hoal Iinh khang khuin, khang n i m va chong oxy hda Nhieu nghifin curu ciing chi ra rang hoat tinh ddi khang vi sinh v^I phu Ihupc vao khdi luong phan tu, muc dp deacetyl hda, pH, ndng dp, nhiet do va muc dp tan h-ong nudc ciia chitosan (Hernandez-Lauzardo el al..
2011). Chitosan tan trong mdi trudng acid va cac nhdm amino tu do tren cac chudi polymer dupc them proton va iam cho nd cd dien tich duong Ve ca ban, ho(iI tinh ddi khang vi sinh vai cua chitosan la do ban chat polycalionic ciia chung, Cac hat nanochitosan khdng nhdng vln giQ dupc cac tinh chat ciia chitosan ma cdn cd nhiJng dac tinh dac biel khac do kich thudc nhd va di?n tich hh mat ldn. Cd nhieu phucmg phip t^o h^t nanochitosan nhung phucnrig phap lien ket ion dupc su dung nhieu hem ca do tinh lien Ipi.
Cic hgt nanochitosan dupc i?o thanh ngau nhien khi hpp nhit polyamon nhu tripolyphosphale (TPP) vao
dung dich chitosan dudi dieu kien khuay lien tuc (Sailaja et al. 2011; Zhao et al, 2011; Mayyas, 2012). Da cd mot sd bao cao ve hoat tinh ddi khang vi sinh vat cua nanochitosan nhung co rat it bao cao ve tuong quan giua kich thudc hat tao thanh va hoat tinh ciia chung, Vi vay Irong bao cao nay, chiing tdi xac dinh mdi urong quan giiia kich thudc h^t nanochitosan lao thanh va hoat tinh uc che sinh trudng ciia vi khuan Gram (•), Gram (+) ciing nhu mdt so chung nam nhu Fusarium oxysporum, va.
Aspergillus awamori.
VAT LIEU VA PHLTiDNG PHAP NGHIEN CLTU Vat li^u
Cac chung vi smh vat Bacillus subtilis, Bacillus cereus. Micrococcus luteus, Listonella damsela, Candida albicans, Fusarium oxysporum. Aspergillus awamori tit bp suu tap gidng cua phdng Cdng ngh?
sinh hpc, vien Hda sinh bien, Vi?n Han lam Khoa hpc va Cdng nghe Viet Nam (VAST).
157
Nguyen Thi Kim Cue et ai Mdi trudng nuoi ciy: Mdi trudng MPB, MPA
cho vi khuin (Peptone 1%, Yeast extract 0,5%; NaCl 0,5%; Agar 1,6% - 2%; pH 7,4 ). Mdi tntdng Czapeck-Dox long va t^n cho vi nam (Glucose 5%;
Peptone 1%; KH2PO4 0,3%; MgS04.7H20 0,3%;
Agar 1,6%) - 2%i; pH 5 - 6). Moi trudng Hansen Idng va rin cho nim men (NaN03 0,3%; K2HP04 0,1%;
MgS04.7H20 0,05%; KCl 0,05%; FeS04 0,001%;
Saccarose 2%; Agar 1,6% - 2%; pH 5 - 6) Phuwng phap tao hat nanochitosan
Chitosan cd khdi lupng phan tii 320 kDa, muc dp deacetyl hda 85% (vien Hda hpc, VAST) duac hda tan trong acetic acid 1% va nudc de dupc dimg dich 0,5%, sau do xu Iy bang vi sdng d 600 w trong 10 phiit. Nho tir tu dung dich TPP (Sigma) vao dung dich chitosan sao cho ti Ie chitosan : TPP la 6:1.
Khuay lien tuc hdn hpp tren d tdc dp va thdi gian khac nhau. Cac hat nanochitosan tao thanh dupc do kich thudc va the Zeta tren may Zetasizer (Vien Khoa hpc vat lieu, VAST).
Phuong phip xac dinh hoait tinh d6i khang vi sinh vSt cua nanochitosan
Cac chung vi sinh vat nghien cuu dupc hoat hda trong mdi Irudng thich hpp (MPB cho vi khuin, Hansen cho nam men, va Czapeck-Dox cho vi nam).
Cay VI smh vat da duoc hoat hda vao moi trudng long thich hap cd bo sung tung loai nanochitosan, chitosan 0,5 % trong acetic acid hoac khang sinh ndng dp khac nhau vdi mat do vi khuan cudi ciing la 10^ - lO^CFU/ml va vi nim 10^- lO^CFU/ml. Sau 24 gid (ddi vdi vi khuan) va 48 gid (ddi vdi nim), ciy trai cac canh trudng nuoi cay len moi trudng dac thich hpp khdng cd nanochitosan, Nudi ti^p va xac dinh lupng khuan lac phat trien tren moi trudng dac.
D61 chung la dng nghiem nudi vi sinh vat khong cd nanochitosan, Thi nghiem dupc lap lai 3 lin.
xac dinh phan tram vi sinh vat bi iirc che sinh trudng bdi cac loai hat nanochitosan theo cdng thicc:
% lie cha = (Ao - A,)/Ao * 100%. Trong do A^ la sd khuan lac mpc tren dia ddi chirng (CFU/ml), A5 la sd khuin lac mpc tren dia thi nghiem (CFU/ml).
Do vi sinh vat dupc nudi trong mdi trudng cd nong dp nanochitosan khac nhau nen cd thl xac dmh
dugc nong dp uc che tdi thieu MICs va ndng d$ gigi vi sinh vat tdi thiSu MBC (Du et al., 2009).
KET QUA VA THAO LUAN
Thu nhan cac liat nanochitosaii kich thuvc Idiic nhan Cd rat nhieu yeu td anb hudng den qua trinh lao hat nanochitosan bang phuong phdp lien ket ion vdi TPP nhu khdi luong pMn tii chitosan, ndng d$ cac chat sii dung, ty le giua chitosan va TPP, tdc dp khuay va thdi gian khuay... Dua vao nhOng k^I qua nghien ciiu ciia tihieu tac gia cung nhu cua cac ddng nghiep trong phdng Cdng nghe sinh hpc, vien Hoa sinh bien, mot sd thdng so trong phan iing lifin kk ion dupc giii nguyen (pH phan iing, ti Ie chitosan : TPP) va chi thay ddi tdc dp khuay ciing nhu thdi gian khuay hdn hap chitosan : TPP nham tao ra cac hat nanochitosan kich thudc khac nhau. Cac h^t nanochitosan tao thanh dupc do kich thudc cQng nhu dien tich be mat bang may Malvern Zetasizer (Bang 1) va chup anhFE-SEM (Hinh I).
Ket qua nh^n duac cho thay tSng thdi gian ho§c tdc dp khuay hdn hpp chitosan : TPP se t^o ra cac hat cd kich thudc nhd han. Sau 2 gid khuiy vdi l6c dp 4000 v/ph, hat nanochitosan thu dupc cd kich thudc khoang 1000 nm. Tang thdi gian khuay Ien 4 gid, kich thudc hat nano tao thanh giara han m$I niia, chi cdn khoang gan 500 nm. Tang toe dp khuay len 8000 v/ph nhung chi de phan iing xay ra trong 1 gid, nanochitosan tao thanh cd kich thudc kha nh6, khoang 100 nm. Thong thudng, kich thudc hat nho dan cung tuang iing vdi viec giam zeta potential cua hat, tuy nhien Irong trudng hap nay, m^c du kich thudc cua hat tao thanh nho khoang 100 nm nhung gia In the zeta van cao, khoang -(-37 ± 5 mV.
Chitosan la mpt polycationic electrolyte vdi cac nhdm amino, trong khi TPP la mpt polyanionic electrolyte vdi cac nhdm phosphate. Cac hat nanochitosan cd the Zeta duong bdi cac nhdm amino va hydroxyl lao cau noi hydro vdi cac nhom hydroxyl hoac nguyen tu oxy cua nudc. Khi bo sung dung dich TPP, dien tich duang tren be mat h^l chitosan bi Irung hoa bdi dien tich am tren nhdm phosphate (Huang el al., 2009).
Bang 1. Anh hu'dng cua qua trinh khuSy len kich t h u d c hat nanochitosan tao IhSnh.
Ki h i f u mau Tdc do khuay (v/ph)
Thdi gian khuay (gig)
Kich t h u d c h^t TB (nm)
T h ^ Z e t a (mV)
Chi s6 da phSn tAti (polydisperslty Index) CSNPs I 4000
CSNPs II 4000 CSNPs 111 8000
1127 450
+49,2 ± 4 , 3 2 0.471 +40.8 ± 7 . 8 1 0,385 + 37.4 ± 5 , 4 1 0,626
Tgp chi Congngh? Sinh hgc 12(1): 157-163, 2014
Fan va dong tic gia (2012) da nghien ciiu anh hirdng ciia tdc dp khuiy hdn hap chitosan: TPP trong phan ling lien ket ion tao hat nano cho thiy khi tang tdc dp khuiy, sir phan bd kich thudc h^t nhd din, dinh phan bd kich thudc hat hep hon, kich thudc hat dong nhat hon. Nhimg ddn mdt nguong nhit dinh, neu tiep tyc tang tdc do khuay se cd hien tupng ddng eye cua cac hat nano. Dieu nay co th6 giai thich khi t6c dp khuiy thich hpp, su phan bd cua TPP trong dung dich chitosan va Iuc cit cd thi tang, cai thien sy phan tan cua cac hat, trong khi khuiy qua ra^nh se
lam mat luc day gida cac h lai vdi nhau.
., dan den cac hat tich tu
Ket qua tren bang 1 va hinh 2 cho thiy sir phan tan hat ciia CSNPS 1 va 11 kha nhd, chi trong khoang 0,4-0,5, Dung dich nanochitosan tao thanh kha ben vimg, khong tao tila sau mot thdi gian bao quan bdi chiing co dien tich b6 mat kha ldn (> -H37). Theo Ing va ddng tac gia (2012) cac hat nano vdi dien tich b6 mat +30 mV hkn vung, dli de ngan su k6t tu cac hat
P Recoai CK1|
Hinh 2. S y phSn b6 kich Ihuoc hat theo c u o n g do cua m l u CSNPI (A) va CSNPII (B)
Dinh gii boat tinh doi khang vi khuan ciia cac hft nanochitosan tao thanh
C6 the thiy, ddi vdi chiing B. subtilis, hoat tinh d6i khang cua cac hat nanochitosan kich thudc khoang 1000 nm va dung dich chitosan tuong duong
nhau, chiing nay bi ire che smh trudng hoan loan d ndng dp cac chat sur dung 100 pg/ml, ndng dd 50
|ig/ml chi ire che hon 50%, Nhung nanochitosan kich Ihudc khoang 100-450 nm co the tieu diet hoan loan B subtilis d nong dp 50 pg/ml sau 24 h tiep xiic (Bang 2) Chiing B. cereus cd linh khang manh ban
159
Nguyfin Thi Kirai Cue et al so vdi cac chiing cdn lai, ngay ca d ndng dp 100
Hg/ml, nanochitosan b'ch thudc khoang 1000 nm Cling chi tieu diet dupc 95%) vi khuan sau 24 h nudi trong mdi tnrdng Idng. Chiing L. damsela man cam nhat, chiing bi lie che sinh trudng 100% d nong do 50 jig/ml cua t i t ca cac Ioai hat nanochitosan va ngay ca chitosan. Kdt qua nay trimg vdi ket qua nghien ciiu ciia Katas va ddng tac gia (2011), yi khuin Gram (-) bi lie che manh hon so vdi vi khuan Gram (-I-). Bao cao cua cac tac gia nay ciing chiing minh hieu qua uc chd smh trudng cua vi khuan thap
h o a khi kich thudc hat tang. Hieu qua lic cb^ vi khuan tang khi kich tbudc hat nhd cd le do tang d i ^ tich tiep xiic ciia hat nano vdi be mSt mang \.k bao vi khuan. Cac hat nano nay ciing cd the hut bam chit len be mat mang te bao, ket qua pha vd mang t£ bao va giet chet vi khuan. Vi khuan Gram (-) bi lie chl manh hon so vdi vi khuan Gram (-I-) cd the do dien tich am be mat ciia vi khuan nay cao hon va chung chiu trach nhiem cho viec gan vdi cac nhdm di?ii tich duong cua chitosan va nanochitosan (Katas et a/.. 2011).
Bang 2. Kha nang dc ch3 sinh trudng vl khuan cua nanochHosan, chitosan va khang sinh (%).
Che pham Ndng do (pg/mt) B. subtilis
CSNPslll
Chitosan
Kanamycin 100 50 25 100 50 25 0,31 0,16
Ghi chu:' Hal chung M. luteus va L damsela sir dung khang sinh amplcilin bdi 2 chiing nay khang vdi kanamycin Ning 6^
amplcllin sir dyng cho M, /oteus la 2,5 jjg/mlva 1.25 pg/ml; cho L damse/a la 0,63 pg/ml vS 0,31 pg/ml ND: khong x^c djnh Tac dung diet khuan ciia chitosan thay doi phu
thudc vao mpt sd nhan td nhu chung loai vi sinh vat, ban chat ciia chitosan, pH, nhiet dp va thdi gian phan ling (Kong el ai, 2010), Trong mpt vai nghien ciiu, hoat tinh khang khuan dupc bao cao manh hon ddi vdi vi khuan G(-), nhung trong cac nghien cuu khac lai ngupc lai. Cung cd nhieu bao cao cho t h i y hoat tinh khang khuan cua chitosan ddi vdi vi khuan G(-) va G(+) khong cd su khac biet dang kk. Cd le do vat lieu ban dau va dieu kien tien hanh thi nghiem cho nhirng kk qua khac nhau (Qi et al, 2004; Kong et al, 2010; Katas el al, 2011). Kdt qua tren bang 2 cho thay chiing B. subtilis chiu dupc tac dpng cua chitosan tot nhit, chiing L. damsela bi lie c h l sinh trudng hoan toan d ndng dp chitosan 50 |tg/ml.
Cd the Ihay cac hat nanochitosan kich thudc tir 100-500 nm cd ho^it tinh ddi khang cac chung vi khuan nghien ciiu gan nhu tuang dirong, va boat tinh
ciia dung dich chitosan tuang duang vdi ho?t Iinh cua cac hat nano kich thudc Idn hon 1000 nm. Kei qua tren bang 3 cung khang djnh hoat Iinh khdng khuan cua cac hat nghien cuu phu thupc khong nhung vao kich thudc cua hat, ma cdn phu thugc vio ban chat cua chung vi khuan. Trong sd cac chiing vi khuan nghien cuu, chiing B. cereus cd tinh khang manh nhat va chung L. damsela m l n cam nhat voi cac loai hat sir dyng.
Hoat tinh khang khuan cua nanochitosan kich thudc khac nhau cung da dupc bao cao. Vdi nhfing hat nanochitosan khoang 1000 nm, ndng dp MICsvJ MBC cho E. coli la 1,95 pg/ml va 15,6 ng/ml, luong ling, nhung cho chiing S aureaus lai len tdi 15,6 pg/ml va 62,5 pg/ml, luong iing. Trong khi do, c4c hat CO kich thudc nhd han (khoang 300 nm) c6 glfi tri MIC va MBC cho hai chiing vi khuin tren nhi hon rat nhieu (Katas er a/., 2012). Nghien ciiu ciia ()i
Tgp chi Cgng nghe Sinh hgc 12(1): 157-163,2014 vi cs. (2004) cung cho t h i y hoat tinh khang khuin ciia nanochitosan mfinh hon gap nhiSu lin so vdi dung dich chitosan (Qi et al, 2004), Kat qua tren bang 2 va 3 cQng khing dinh hoat tfnh khang khuin
cua nanochitosan tdt hon dung dich chitosan, va cac hat nanochitosan kich thudc nhd hon iirc ch^ sinh trudng cua cac chung vi khuin nghien ciiu manh hon.
Biing 3. Xdc djnh MICs va MBCs cho cdc chung vi khuin nghlSn o J (pg/ml).
B. subtilis B. cereus M. luteus L. damsela
0,16 0,20 1,00 0,20
0,31 0,31 2,50 0,63
D i n h g i i hoat tinh doi Idling vi n i m cua cac hat nanochitosan tao t h a n h
Tuong tu nhu ddi vdi vi khuan, cac chiing nim nghien cdu dupc nuoi trong moi trudng ldng cd chua nanochitosan, chitosan hoac thuoc khang nam vdi cac ndng dp khac nhau. Sau 48 gid, ciy frai dich nuoi len moi trudng dac thich hpp khdng bd sung cac chat tren.
Xic djnh lupng khuan lac tao thanh (Bang 4), Ket qua nhan dupc cho thay chung A. awamori khing kha tot cac che pham nanochilosan/chitosan sii dung. C i c hat nanochitosan nhd hon cd kha nang dc che sinh trudng cac chiing nam tdt hon, F.
oxysporum bi lie che hoan toan bdi cac hat nanochitosan kich thudc 100 nm d ndng dp 16
pg/ml, trong khi can tdi 50 pg/ml miconazole. Nhin chung, cac hat nanochitosan ca 3 kich thudc deu cd hoat tinh chdng nam F oxysporum manh ban so vdi miconazole. Ngupc lai, chung A. awamori cue ky khang cac hat nanochitosan, Phai cin Idi 500 Mg/ml nanochitosan kich thudc tir 100-500 nm mdi irc chl hoan toan smh trudng ciia chiing nay, va ddi vdi hat nanochitosan kich thudc hon 1000 nm, nflng dp su dung cdn ldn hon nhieu (Bang 4). Theo mpl sfl tic gia, sd dl cac chung nam thufle chi Aspergillus cd tinh khang doi vdi nanochitosan manh hon bdi chitosan la mdt trong cac hop phan ciia Ihanh Ie bao ciia chiing (10% chitosan trong thanh t l bao Aspergillus), vi vay chiing khang manh hon vdi chitosan dua hi ngoai vao (Ing et al. 2012).
Bing 4. TT 1$ n^m bj i>c che sinh trudng bdi cac chit nghien cii'u (%) Sin phSm
CSNPsI CSNPs II CSNPs III Chitosan Miconazole'
Nong dp cac san pham 5i> dung (pg/ml)'
Ghl chu: * N6ng d^ Miconazole SCP dgng la 50 pg/ml va 25 pg/ml cho hai chung F oxysporum va A awamori D6I vdi chung C. albicans n6ng (fO miconazole dupc sd dyng Id 10 pg/ml, 5 ^jg/ml va 2,5 )jg/ml. ND' khong xac ijinh
Bang 5 mpt lan nUa cho thay A. awamori khang rat tdt cac loai hat nanochitosan cung nhu dung dich chitosan, tiep theo la chiing C albicans va chiing F.
oxysporum min c i m nhat trong ba loai nim nghien
cuu, Chung F oxysporum cd gia tri MIC va MFC cdn thip hon ca miconazole, dac biet cac loai hat nanochitosan kich thudc tir 100-500 nm cd gii trj MIC la 7,8 pg/ml va MFC la 25 pg/ml, Irong khi gia
161
Nguyen Thi Kim Cue et ai tri tuong ting ciia thuoc chdng nam miconazole la 35
|ig/ml va 50 |tg/ml.
Rit it nghien ciiu dupc bao cao ve inh hudng ciia kich thudc hat nanochitosan den hoat tinh lie che sinh trudng cua cac chiing nam. Theo Ing va dong tac gia (2012), cac hat nanochitosan co hoat tinh lic che nam tdt hon so vdl dung dich chitosan v i hieu qua lie che bi anh hudng bdi kich thudc va the Zeta ciia hat nanochitosan. Nhimg nghien ciiu gan day cho thay, mang plasma tao rao chin chitosan trong cic chimg khang chitosan. Trong cac chung nam man cam vdi chitosan cd nhieu acid beo khdng no hon so vdi cua cac chung nam khang chitosan, cho rang tinh tham ciia chitosan co the phu thudc vao tinh luu ddng ciia mang (Hernandez-Lauzardo el al, 2011).
Nanochitosan polycationic cd dien tich be mat ldn tuong tic hieu q u i voi nam va co ai luc cao gan vdi tebao vi nam (Kaur et al., 2012). Cac hat nano cd dien tich be mat tdn va cd Ihl hiit bam chat len b l mat l l
bao nam, pha v o tinh loan ven cua mang te b i o . Ngoii ra, cic hat nanochitosan cd the khuech t i n vao Irong il b i o v i gan k i t vdi DNA ciia te bao, tii dd lic chl s^
tong hpp mRNA, lira anh hudng den viec san xuit protein va enzyme can thiet ciia te bao (Ing et al, 2012) . Kich thudc hat nano giCr vai trd quan trpng trong viec x i c dinh hoat tinh ddi khang vi sinh vat cua cac hat nano bdi chiing di vao trong t l bao thdng qua cac protein van chuyen hoac kenh ion. Vi vay, cac hat nhd hon se de dang di vao trong te bao han. Dien tich be mat ciia cac hat cd vai trd trong hieu qua lie chl ciia cac hat nano la do dien tich duong cua chung cai thien tuong tac giiia hat nanochitosan va b l mat t l hao VI sinh vat tich dien am. Kei qua iam cho thanh t l bao cua nam bi thay doi va cuoi ciing cac chit trong t l bao bi ri ra ngoai va din tdi Ie bao bi chet (Hemindez- Lauzardo et ai, 2011; Ing et ai, 2012; Kaur el al, 2012). Nhin chung, cic hat nanochitosan cd boat tinh ddi khang nam manh hon so vdi dung dich chitosan (Bang 4, 5).
Bang 5. Xac d|nh MICs va MFCs cho cac chung nam nghien cuu (pg/ml).
CSNPsI CSNPs II CSNPs 111 Chitosan Miconazole
MIC C albicans
MFC MIC
F. oxysporum
MFC MIC
A. awamori MFC
TAI LIEU THAM KHAO Vdi viec thay dfli van tdc va thdi gian khuiy hdn
hop chitosan: TPP, ba loai hat nanochitosan kich thudc khoang 1000 nm, 500 nm va 100 nm da dupc tao thanh Cac hat nanochitosan cd kich thudc nhd hon cd hoal tinh doi khang vi smh vat manh hon so vdi cac hat cd kich thudc Idn. Chiing vi khuin Gram (-) L. damsela man cam vdi cac loai hat nanochitosan ban so vdi cac chiing Gram (+). Chiing VI nam Ihupc chi Aspergillus khang tdt cac loai hat nanochitosan nghien citu.
Ldi cam on: Cong trinh dugc hodn ihdnh vdi sic ldi trg kinh phi ciia Di tdt doc lap cdp Nhd nuac, md s6 DTDL.2011-G/66/HD Bo Khoa hgc vd Cong nghe cdp.
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T H E I N F L U E N C E O F P A R T I C L E ' S S I Z E O F N A N O C H I T O S A N O N A N T I M I C R O B I A L A C T I V I T Y
Nguyen Thi Kim Cue'*, Tran Thi Kim DHag^ Pham Viet Cuong''^
'institute of Marine biochemistry, Vielnam Academy of Science and Technology
^Scientific Research Instilule Central, Vietnam Academy of Science and Technology
SUMMARY
Chitosan has been used extensively in many different fields due Co it's biocompaUble, non-toxic nature, anti-microbial, anti-fungal and antioxidant activities The nanochitosan particles inherit not only the properties of chitosan but also possess other special characteristics since small size and large surface area Some reports have been published on the anhmicrobial acUvity of nanochitosans but very few of correlation between particle size and their antibacterial activity We've created 3 types of nanochitosan with different sizes by ionic gelation method changing stirring speed and stirring duration of chitosan . tripolyphosphale (TPP) mixture. When using the stirring speed of 4,000 rpm for two hours, the formed nanochitosan particles were about 1,000 nm, the increase of duration up to 4 hours, the size of particles decreased to a half, about 500 nanometers Increasing the stimng speed up to 8,000 rpm for 1 hour, nanochitosan particles with size about 100 nanometers have been created The antibacterial and antifungal activities of the formed chitosan nanoparticles has been evaluated.
The results showed that received nanochitosans inhibited the growth of investigated bactena and flingi stronger than chitosan solution. The smaller nanoparticles exhibited anUmicrobial acUvity better than bigger one The Gram (-) bacteria L. damsella was more sensitive to all types of nanochitosan particles than the Gram (+) bacteria (Bacillus and Micrococcus). Among three mvestigated fimgi, A awamori strains resisted chitosan solution as well as nanochitosan particles.
Keywords' Antimicrobial, bacteria, fitngi, ionic gelation, nanochitosan
' Author for correspondence: Tel: +84-906221581, E-maiL kcnmivenihi&lgmad.com
