| The chemically modified electrode (CME) is currently a very flourish research realm in the electrochemistry and electroanalytical chemistry. The study of CME on environment and life science fields has become one of the most important chemical applications. Nanoparticles have many extraordinary features such as huge specific surface area, strong catalytic activity and good bio-compatibility. Study on the electrochemical behavior of hydrogen peroxide and monosaccharides on the nanoparticles modified electrode is one of the main research works of the thesis, which involves the following subjects:1. Study on the electrochemical behavior of hydrogen peroxide on the Nano-PB/poly-(L-Cys) modified Pt electrodeA novel Nano-PB/poly-L-cysteine film modified Pt electrode was fabricated. The electrochemical properties of hydrogen peroxide (H2O2) on the modified electrode were studied and a new method for the determination of H2O2 was developed. In the phosphate buffer of pH 4.5, The reduction peak current has a good linear relationship with the H2O2 concentration in the range from 1.5×10-5 to 1.52×10-3 mol/L with a correlation coefficient of 0.9996. The detection limit was 4.2×10-7 mol/L (S/N=3). The time to obtain stable current was below 9 s. The experimental results showed that the modified electrode has the characteristics such as simple fabrication, high sensitivity, rapid response and high selectivity.2. Electrochemical behavior of hydrogen peroxide on prussian blue nanoparticles immobilized platinum electrode 13653405895 A novel hydrogen peroxide sensor was prepared by immobilizing prussian blue nanoparticles on a platinum electrode with positive electrical charge by virtue of the principle of electrostatic adsorption. Cyclic voltommogram and chronoamperometry were employed to study the electrochemical characteristics of the sensor. The immobilized prussian blue nanoparticles exhibited an excellent electrochemical activity toward the reduction of H2O2. The experimental results showed that under optimum conditions, the linear range of the sensor for H2O2 was 4.0×10-6 mol/L to 4.0×10-5 mol/L, and the detection limit was 5.1×10-7mol/L. The sensor exhibits the features of fast response, high sensitivity, easy fabrication and strong anti-interference ability.3. Recognition of glucose at a glassy carbon electrode modified with 4-mercaptop -henylboronic acid/Nano-gold films.A 4-mercaptophenylboronic acid/Nano-gold film modified glassy carbon electrode (MPBA/NG/GCE) was fabricated based on the self-assemble of MPBA on the surface of glassy carbon electrode modified with gold nanoparticles and its surface electrochemical characteristic was evaluated with cyclic voltammetry and electrochemical impedance spectroscopy. The electrchemical behavior of glucose on the modified electrode has been studied and the optimum conditions for the determination of glucose using this modified electrode were discussed. The results showed that the presence of gold nanoparticles could enhance the electroactivity of glucose at the modified electrode. The current response of MPBA/NG/GCE increased linearly with the glucose concentration in the range of 1.0-150.0 mmol/L with a detection limit of 3.8×10-5 mol/L (S/N=3), The linear regression equation is△ip(μA)=0.337+0.0342C (C, mmol/L) with correlation coefficient of 0.999. This method can be used to the recognition of glucose.4. Electrochemical characterization of in situ functionalized gold p-aminothiophenol self-assembled monolayer with 4-formylphenylboronic acid for recognition of sugarsThe surface of a gold (Au) electrode was modified with p-aminothiophenol (p-ATP) and formed well-packed monomolecular layers through a sulfur-Au bond. Functionalization of ATP/Au self-assembled monolayer with 4-formylphenylboronic acid (BA) via Schiff s base formation, through in situ method to fabricate BA/ATP/Au electrode is presented. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements were used to investigate the changes of electrode behavior after each assembly step. The surface pKa value of the BA/ATP/Au electrode was estimated by CV and EIS. In the presence of sugar, the terminal groups of BA/ATP/Au electrode can react with sugar by forming the phenylboronate esters of sugar on the surface of the electrode and the pKa values for the BA/ATP/Au electrode in the presence of different sugars (D-glucose, D-fructose, and D-mannose) were also obtained. The fabricated electrode can be used as a novel biosensor for determining sugars on the basis of the change in ip of the Fe(CN)63-/4- ion in the presence of sugars. The biosensor exhibited excellent performances for determining D-glucose, D-fructose, and D-mannose with low detection limits, wide linear ranges and good sensitivities.
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