Electrochemical Biosensors Based On Surface Grafted Monolayers And Composites Modified Electrodes

A detailed review for the covalently monolayer and multilayers modified carbon electrode and the applications of carbon nanotubes in chemically modified electrode was carried out. Based on the previous results of amino acid and choline modified carbon electrodes in our laboratory, the fabrication and applications of electrochemical biosensors based on surface grafted monolayers and composites modified electrodes are reported. A series of covalent monolayer and multilayers modified carbon electrodes, such as 5-hydroxytryptophan (5-HTP), poly (vinyl alcohol) (PVA) and choline (Ch) covalently modified glassy carbon electrodes (GCEs) were obtained by use of electrochemical methods. These obtained electrodes were characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and electrochemical impedance spectroscopy (EIS). The neuronal monoamines such as dopamine (DA) and serotonin (5-HT), some coexisting substances in physiological system such as ascorbic acid (AA) and uric acid (UA), and some estrogens such as estradiol, estrone and estriol have been analyzed using above obtained modified carbon electrodes. The dissertation is mainly focused on the following aspects:5-hydroxytryptophan (5-HTP), serotonin (5-HT), Tryptophan (TRP) and poly (vinyl alcohol) (PVA) covalently modified glassy carbon electrodes (GCEs) were fabricated using cyclic voltammetry (CV). The reaction mechanism was proposed based on the experimental results, which was some cation radicals could be produced during the anodic scanning, and carbon-nitrogen bond was formed between modified molecules and GCE surface. It was found that these obtained electrodes could catalyze some biologically small molecules such as AA, DA, AA and 5-HT, and some sensitively and selectively electrochemical methods were successfully...