Study On The Preparation And Application Of Mercaptothiazole Derivative Modified Gold Electrodes

The preparation and electrochemical behavior of 2-hydroxy-4-methoxy benzaldehyde(HMB), 2-mercapto-1, 3, 4-thiiodiazole(MTD), 2-amino-5-mercapto-1, 3, 4-thiiodiazole(AMTD), and 5-mercapto-1-methyltetrazole(MMT) modified gold electrode were studied by cyclic voltammetry(CV), electrochemical impedance spectroscopy(EIS) and scanning electron microscopy(SEM), respectively. The effects of modification and electrochemical reaction conditions on the electrochemical behavior of the chemical modified electrodes were discussed.1. The morphology of HMB, MTD, AMTD and MMT modified Au electrodes were characterized by SEM, and self-assembled membranes of the modifier were obviously observed.2. The electrochemical behaviors of Fe(CN)63-/4- on bare Au, HMB/Au, MTD/Au, AMTD/Au and MMT/Au electrode were examined by cyclic voltammetry, respectively. The peak potential difference ΔEp of Fe(CN)63-/4- on HMB/Au and AMTD/Au electrode was 68 m V and 81 m V, respectively. The peak current ip was decreased obviously, and the reversibility of the electrochemical reaction of Fe(CN)63-/4- was decreased. The peak potential difference ΔEp of Fe(CN)63-/4- on MTD/Au and MMT/Au electrode was 60 m V and 62 m V, respectively. The peak current ip was increased obviously, which means a positive effect on the electrochemical reaction of Fe(CN)63-/4-.The EIS results indicated that the electrochemical reaction of Fe(CN)63-/4- on HMB/ Au, MTD/Au, AMTD/Au and MMT/Au electrode was mainly diffusion controlling process.3. The promotion effect to the electrochemical reaction of cytochrome c was observed, when bare Au electrode was modified in p H6.0 HMB-phosphate buffer solution(PBS) solution for 6 h. The peak potential difference was about 62 m V. The peak current ip was positively correlated to the square root of potential scanning rate(v1/2), and the peak current ratio ipa/ipc was nearly 1, indicated that it was a diffusion controlled quasi-reversible process.4. The MTD/Au, AMTD/Au and MMT/Au electrode had remarkable promotion effect on the electrochemical reaction of dopamine(DA), but almost had no obvious promotion effect on the electrochemical reaction of cytochrome c.5. The electrochemical behavior of dopamine on MTD/Au, AMTD/Au and MMT/Au electrode was investegated by cyclic voltammetry. There was no significant reduction peak current in the cyclic voltammetric curve of the dopamine on the bare gold electrode. The cathodic reduction peak current ipc of DA on the modified gold electrode was increased with the increasing of potential scan rate, and was positively correlated to the square root of potential scanning rate(v1/2). Meanwhile, the oxidation peak current ipa and the peak potential difference ΔEp of DA was also increased. The peak potential difference ΔEp of DA on MTD/Au, AMTD/Au and MMT/Au electrode under the potential scanning rate of 50 m V/s was 94 m V, 82 m V and 85 m V, respectively.6. The cathodic peak current ipc of DA was linear correlated with DA concentration, which can be used for the selective electrochemical detection of dopamine. The linear correlation curve of DA on MTD/Au electrode was ipc(μA) = 7.6050C(mmol/L) + 0.4363, r=0.9901. The effects of ethanol, glucose or sodium nitrite on the detection of DA were discussed, respectively.7. The peak current ip of DA in 1.0 mmol/L DA-PBS solution on MTD/Au electrode was kept stable atleast for 6 h, when it was exposed to air avoid of light. When the MTD/Au electrode was soaked in distilled water or PBS solution, it can be kept stable for 12 h.