Application Of Metal Nanoparticles / Mercapto - Graphene Composites In Catecholamines Analysis

Dopamine(DA) and epinephrine(EP) are important catecholamine neurotransmitters in the central nervous system, play an important role in human health, and therefore determing the content of catecholamines have important practical significance. Functionalized graphene was highly concerned by researchers because of its unique performance advantages. And the number of research projects was the huge increase. Metal nanoparticles materials due to their high catalytic activity, high sensitivity and stability, can play an important role in improving the electroanalytical performance of the modified electrode. Therefore, it was of important significance to prepare the new electrochemical sensor with functionalized graphene and Metal nanoparticles in the determination of DA and EP.The main work is as follows:1. An electrochemical sensor was prepared by deposited gold nanoparticles on a thiol group functional grapheme(SH-GR) modified glassy carbon electrode(AuNPs/SH-GR/GCE). With DA as a probe,optimal deposition voltage, deposition time, dispensing volume, base solution acidity, scan rate, accumulation time of the modified electrode were discussed via cyclic voltammetry(CV). In the pH=4.0 McIlvaine buffer solution, the modified electrode exhibits good electrical catalysis to DA. The relationship between DA oxidation peak current and concentration was investigated by differential pulse voltammetry(DPV). The anodic peak current of DA was in a good linear relationship with concentration in the range of 1.1×10-5 ~ 3.2×10-4mol/L. The linear regressive equations was I(μA)= 4.1204 + 0.2247 CDA(μmol/L),with correlation coefficients of 0.998. The detection limit was 2.0×10-7 mol/L. The method showed favorable sensitivity, selectivity, reproducibility and stability for the determination of DA without the interference of uric acid(UA) and ascorbic acid(AA), which has been applied to the analysis for serum sample, and the assay result was satisfactory.2. The AuCo alloy nanoparticles(AuCo NPs) were formed on a thiol group functional graphene(HS-GR) modified electrode by an electro-depositing method. The modified electrode was denoted AuCoNPs/SH-GR/GCE. Using DA as a probe, the electrochemical behavior of DA was studied by CV and DPV. Under ideal conditions, the modified electrode can be used for the selective determination of DA, UA and AA. The linear concentration range of DA, AA and UA were 2.1~21.1μmol/L, 10.0~100.0μmol/Land 9.0~60μmol/L, respectively, with the detection limits(S/N =3) of 0.1, 4.0 and 1.0μmol/L. The modified electrode showed high sensitivity and selectivity, can be applied to the determination DA of human serum to obtain satisfactory results.3. The electrochemical behavior of EP was investigated on AuCoNPs/SH-GR/GCE. Thebest conditions of the determination of EP were studied in the experiments. The modified electrode showed good reproducibility and stability. Under the optimal conditions, the DPV oxidation peak current of EP was in a good linear relationship with concentration in the range of1.0×10-6~ 1.0×10-4mol/L. The linear regression equations could be expressed as I( μA)=0.5258CEP(μmol/L)+4.3810,r=0.998. The detection limit was 8.0×10-7mol/L. The method can be applied to the analysis of human serum sample of EP.