TAP CHI HOA HOC T. 51(1)51-54 THANG 2 N A M 2013
C A M BlfeN HUYNH QUANG CHON LOC ION Hg^* Dl Tir
DAN X U A T FLUOiRESCEINPhan TIT Quy', Nguyen Dinh Luyen^, Nguyen Chi Bao^, Nguyen Dang Dan^ Tran Du•o•ng^
Nguyen Thi Quynh Oanh^, Duo'ng Tuan Quang^"' 'Dgi hgc Toy Nguyen
^Dai hoc Hue Din Tda soan 25-9-2012
Abstract
Fluorescent sensor for Hg'"^ ions based on a fluorescein derivative (FS) has been synthesized and characterized by a variety of methods. FS itself was non-fluorescent but upon the addition of Hg^"^, it gave rise to strong fluorescence emission due to irreversible desulfurization reaction with the spirolactam ring-opening process, followed by cychzation of a thiosemicarbazide to form 1,3,4-oxadiazole. Furthermore, the Hg^*-triggered fluorescence response was not affected by other metal ions such as Ag', Pb^^ Cd^*, Cr^', Zn^\ Fe^\ Co^\ Ni^^ Ca^\ Mg^"", K^ and Na^ indicating that FS could selectively detect Hg^*^ ions.
Keywords- Fuorescenl sensor, fluorescein, mercury.
I.DATVANDE
Kim loai nang la mdi quan tam Idn, khdng chi trong cdng ddng khoa hgc, dac biet la cac nha hoa hgc, sinh hgc, va bao ve mdi trudng, ma ngay ca trong cgng ddng dan cir ndi chung. Trong sd dd, thuy ngan la mgt trong cac chat d nhiem nguy hiem va phi biln, phat thai thdng qua cac hogt ddng ty nhien hoac cac boat ddng cua con ngudi [i-3]_. Mdt si vi sinh vat san xuat metyl thuy ngan-mgt chat doc thin kinh manh, tir cac dgng tdn tgi khac ciia thiiy ngan, gay ra nhung van de sue khde nghiem trgng bing each pha hoai he thdng thin kinh trung uang va tuyin ngi tilt, dan den sy rdi logn ve nhgn thdc va van dpng [4], Diiu nay la do tinh thim rat cao qua da, hd hap va he tieu hda cua ca the con ngudi.
Nhilu con dudng lay lan thiiy ngan thdng qua khdng kht, nudc, thuc pham dem lgi mdi quan ngai ldn bdi . vi nd tdn tgi trong mdi trudng, va sau do tich liiy chit ddc trong ca thi thdng qua chudi thirc an [5, 6].
Nhihig ly do dd da thiic day cac nha khoa hgc tim kilm nhifng phuang phap xac djnh ion thiiy ngan lir cac mlu sinh hgc va mdi trudng. Mdt sd phuang phap, bao gdm quang pho hip thu nguyen tir, quang phd phat xa nguyen tir plasma ghep ddi cam irng, cam biln dien hda,...cd thi phat hien ion thiiy ngan d gidi hgn thIp [7-10]. Tuy nhien, cac phuang phap nay ddi hdi thilt bj dit tiln va cac thao tac cin mil nhilu thdi gian. Trong khi dd, phuang phap huynh
quang cho phep thyc hien pbep phan ti'cb tuang ddi de dang, it tdn kem va rat nhay. Da cd nhieu cdng trinh cdng bd lien quan den viec sir dung phuang phap huynh quang thdng qua cac cam bien phan tir (chemocam bien/chemodosimeler) de phan ti'ch ion thiiy ngan vdi do nhay va do chgn Igc cao. Tuy nhien, cac nha khoa hgc van khdng ngirng lim kiem nhiJng cam bien huynh quang mdi cd do nhay va do chgn Igc cao vdi vdi ion Ihiiy ngan de dap ung nhu clu phan tich ngay cang ldn trong thyc te. Tiep theo cac cdng trinh ciia chiing tdi ve cam bien huynh quang phat hien cac ion kim loai nang [11, 12], bai bao nay trinh bay sy tdng hgp, dac trung va mdt sd tinh chat huynh quang ciia dan xuat fluorescein, cd kha nang ung dung phan ti'cb ion thiiy ngan.
2. THUC NGHIEM 2.1. Thiet bi
Cac pho huynh quang dugc do tren may Hitachi F-4500 sir dyng cuvel thach anb 10 mm. Pho ' H - NMR dugc ghi tren may phd Bruker-400 (400 MHz).
Phd khdi lugng dugc ghi tren may 4021C MS.
2.2. Hoa chat
Fluorescein, benzyl thiocyanate va cac dung mdi dugc mua tir hang Merck, sit dung tryc tiep khdng
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qua tinh che them. Cac muoi AgCI04, Pb(CI04)2, Cd(C104)2, HgClj, CrCb, Zn(CI04)2, FeCb, C0CI3, NiCb, Ca(CI04)2, Mg(C104)2, KCI va NaCI dugc mua tir hang Aldrich, thugc logi PA. Nudc cat hai lan dugc sir dyng trong sudt qua trinh thi nghiem.
2.3. Tdng hgp
Tdng hgp Fluorescein hydrazid: Fluorescein hydrazid dugc tdng hgp nhu sau [1]: Cho 1,9 gam (5 mmol) fluorescein da hda tan trong 100 ml metanol
Duang Tudn Quang vd cgng if vao lugng du hydrazin nggm nudc (5 mL; 0,16 mol) rdi dun hoi luu trong 10 gid. Sau dd dung djch phan irng dugc lam Ignh va cho bay hai trong chan khong se thu dugc chat long mau nau thim. Chat Idng nay dugc ket tinh lgi tir dune djch axeton-nudc (30/70, v/v) se thu dugc chat rln mau vang nhgt (0,92 g;
47%). San pham dugc kiem tra sic ky ban mdngva ghi pho ' H - N M R : (DMSO-d6): 5 9,90 (s, 2H), 7,85 (m, IH), 7,57 (m, 2H), 7,08 (m, IH), 6,60 (d, 2H), 6,50-6,42 (m, 4H), 3,90 (s, 2H).
CH3OH
Sodd J: Phan ung tdng hgp Fluorescein hydrazide Tdng hgp FS: Hda tan 1,73 g (5 mmol)
fluorescein vao 15 mL DMF. Hda tan 1,1 g (7,5 mmol) benzyl thiocyanat vao 10 mL DMF. Trgn lan hai dung djch lgi vdi nhau. Khuay dung dich thu dugc 48 gid d nhiet dg phdng. Cho dung dich vao NaCI bao hda se xuat hien chat ket tiia mau cam.
Lgc kel tiia va rira bang etanol se thu dugc chat ran
mau vang nhgt. San pham sau do dugc ket tinh lgi tir etanol/nudc, thu dugc 1,56 gam FS (63%). San pham dugc kiem tra sac ky ban mdng va ghi pho 'H- NMR: (400 MHz, DMS0-d6): 5 9,89 (s, 2H), 9,46 (s, IH), 8,99 (s, IH), 7,93 (d, IH), 7,66 (m, 2H), 7,23-7,14 (m, 8H), 6,61 (s, 2H), 6,43 (s, 2H), 4,37 (s, 2H). MS (MH'): 498,6 (tinh), 498,3 (tim thay).
cr^'
Sa dd 2: Phan irng tdng hgp FS 3. KET QUA VA THAO LUAN
Sy phat hien ion Hg^* bdi FS dugc thuc hi?n nhu sau. Chuan bj cac dung djch goc ciia FS trong acetonitrile, ion kim loai trong nudc, va dung djch dem Hepes d pH 7. Lugng tinh toan dung dich goc (FS, Hg^*) va dung djch d$m Hepes (10 mM) dugc cho vao dng nghiem. Hdn hgp dugc pha loang bing axetonitril va nudc de dugc dung djch cuoi cd nong dp cac chat mong mudn va ti le axeton itril/nudc la 50/50 theo the tich. Lac nhp dung djch roi dl yen 15 phiit va dem do phd UV-Vis, pho huynh quang d nhiet dg phdng.
Dung dich ciia FS khdng mau nhung khi them ion Hg^"^ vao diing djch axetonitril-H20 (50/50, v/v) cua FS thi se thay dung dich chuyin sang mau vang nhat.
chiing td da cd phan ung tach logi luu huynh gay nen bdi Hg . Do cd cau triic vdng spirolactam nen dung djch cua FS khdng phat huynh quang. Tuy nhien, voi sy cd mgt cua ion Hg^* thi dung djch FS phat huynh quang (d budc sdng 537 nm, mau xanh la cay) kha mgnh khi nd dugc chieu bdi den tu ngogi. Hau het ion kim logi thir nghiem khac khdng gay bien ddi huynh quang, chi cd Ag^ lam phat huynh quang vdi cuong dp yeu. Cudng dg hip thy va cudng dg huynh quang cua dung djch FS-Hg^* khdng thay ddi khi nd du9C xO ly vdi EDTA, cho thay phan limg giira Hg^* vdi FS ia bat thugn nghjch, khdng cd sy hinh thanh phijrc chat ciia Hg^^ vdi FS. Hi?n tugng do dugc ly giai ladoii lye mgnh ciia Hg^* vdi luu huynh, hinh thanh HgS kem theo sy md vdng spirolactam, sau do tgo vong 1,3,4-oxadiazole (sadd 3) [13,14].
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H g "
Cdrn bien huynh quang chon lgc...
*HgS
Sa do 3: Phan lirng md vdng spirolactam dudi tac dyng ciia ion Hg^^
Khi them cac Iugng khac nhau ciia Hg^*^ vao dung djch FS vdi ndng dg 0,1 nmol/L d pH 7,0, cudng dg huynh quang tang len cho den luc ndng dp Hg^* dat 0,1 jimoI/L, sau dd cudng do hlu nhu khong thay doi khi tang Hg'*, chiirng td Hg^* tac dyng vdi FS theo hf so li Iugng 1:1. Sy phy thugc cudng dp vao thdi gian ciia h? FS-Hg^* cung da dugc nghien cuu. Cd thi thay ring, tin hi?u huynh quang ciia FS tang len trong 15 phut dIu va cudng dp hau nhu khdng thay ddi sau dd. Do dd, cac thi nghiem dIu dugc thyc nghi?m sau 15 phiit phan irng.
W a v e l e n g t h (ni
Hinh 1: Phd huynh quang ciia FS (1,0 |j,moI/L) trong axetonitril-nudc (50:50, v/v) vdi sy cd mat ciia Hg^*
pH = 7 (dem Hepes). Ndng dg Hg^"*: (a): 0 p.mol/L;
(b) 0,2 fimoi/L; (c) 0,4 pmol/L; (d) 0,6 ^mol/L; (e) 0,8 nmol/L; (f) 1,0 ^mol/L. Budc sdng kich thich:
509 nm. Hinh Idng: Huynh quang ciia he FS-Hg * khi dugc chieu bdi den tu ngogi Hinh 2 bieu dien sy bien ddi huynh quang ciia dung djch FS khi them cac ion kim logi khac nhau, bao gdm Ag", Pb^^ Cd^^ Cr'', Zn^\ Fe^\ Co^\
Ni^\ Ca^^ Mg^^ K*, Na* va Hg^*. Cd thi thIy ring Ag"^ cijng lam tang cudng dg huynh quang cua FS nhung khong dang ke, cdn cac ion kim logi khac hau nhu khdng gay anh hudng din kha nang phat huynh quang ciia FS. Do chgn Igc cao ciia FS ddi vdi ion Hg^* cd the giai thich la do sy tgo thanh HgS vdi dg tan rlt be iam cho phan ung md vdng cua FS rat hieu qua.
3 0 0 -
-T 2 5 0 -
2. 3
ntenslty
i 1
Fluorescence
0'
- ^
T T T0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 W a v e l e n g t h ( n m )
LPmh 2' Cudng dg huynh quang ciia FS (1,0 |imol/L) khi them cac ion kim logi khac nhau vdi ndng dg 1,0 (imol/L. (1) FS ty do; (2) FS+Ag'; (3) FS+Hg^'; (4)
FS+Pb^"; (5) FS+Cd^^ (6) FS+Cr^"; (7) FS+Zn^^
(8) FS+Fe^*; (9) FS+Co^^ (10) FS+Ni^"; (11) FS+Ca^"; (12) FS+Mg^'; (13) FS+K"; (14) FS+Na'
Chiing tdi cung tien hanh thi nghiem khao sat sy bien ddi huynh quang ciia dung djch chira FS va Hg^* khi thay ddi pH. Kcl qua nghien ciru cho thay cudng do huynh quang tang khi tang pH cua dung djch va giu khdng doi trong khoang pH tir 6,5 din 8,5 Trong khi dd dung dich chi chira FS khdng phat huynh quang trong khoang pH khao sat. Dieu nay cho thay, FS cd the irng dung tdt cho viec phan tich Hg^"* khdng nhung cho cac mau mdi trudng ma cdn cho cac mau sinh vat sdng.
4. KET LUAN
Chiing ldi da tdng hgp dugc dan xuat fluorescein d dgng ddng vdng cd the phat hien chgn loc ion Hg^*. Co sd ciia phuang phap dya tren phan irng tach logi luu huynh bdi Hg^*, tao san pham FS d dgng md vdng cd kha nang phat huynh quang manh.
pH tdi uu cho sy phat huynh quang nam trong khoang 6,5-8,5. Trong sd cac ion kim loai khao sat, chi cd ion Hg * lam cho FS phat huynh quang mgnh. Dieu nay cho thay FS cd the phat trien thanh cam bien tdt cho ion Hg^* de irng dyng trong thyc tl.
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L d i c a m ffn: Cong trinh ndy dirac hoan thdnh vdi sij- ho trg ldi chinh tir Quy Nafosted cho de tdi, ma sd 104.07.17.09
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