The Formation Of Amphiphilic Core Shell Polymer Film Modified Electrodes And Its Enhanced Action In Direct Electron Transfer Of Glucose Oxidase

Polymer has excellent chemical and physical properties. The property makes them very useful in the electrochemical sensor material. In this paper, we modified amphiphilic polymer PDMAEMA-protonated corona and hydrophobic polystyrene core(PDS) on the electrode to obtain polymer film with better stability and excellent electricity. PDS has been adopted as the matrix to immobilize glucose oxidase(GOD) to facilitate the direct electrode transfer between GOD and electrode. Phosphomolybdic heteropoly acid was also adsorbed by electrostatic attraction on the glassy carbon electrode modified by PDS. Our goal is to explore new application of amphiphilic core shell Polymer (PDS) as a new electrode material in modified electrode and biosensor.The dissertation is divided into three sections.In the first part of this paper, the conditions of formation were studied and optimized. We modified PDS on the electrode by dipping. The dipped time and the concentration of polymer were discussed. The polymer film was characterized by Scanning electron microscope (SEM). The stability and electricity of the obtained electrode were discussed. The results showed that PDS has a good infection on the stability, current response.In the second part of this paper, glucose oxidase (GOD) was stably immobilized on glassy carbon electrode modified by PDS. The sorption behavior of GOD immobilized on PDS film was characterized by scan electron microscopy (SEM). Cyclic voltammetry (CV) was used to investigate the electrochemical behavior of the modified electrode and bioelectrocatalytic activity of enzymes. The experimental results showed that GOD underwent effective and stable direct electron transfer reaction at the surface of PDS/GC electrode with a pair of nearly symmetrical,redox peaks in phosphate buffer solution. The formal redox potential, E0, is almost independent on the scan rates and the average value of E0 for GOD is - 0.447 V (vs.SCE, pH6.24). The dependence of E0 on the pH of the buffer solution indicates that the direct electron transfer of GOD is a two-electron-transfer reaction process coupled with two-proton-transfer. The apparent heterogeneous electron transfer rate constant (k) is 3.9s-1. Above all, PDS can alter the microenvironment of the active site of GOD, and facilitate the direct electrode transfer between GOD and electrode. Confirmation of the retained bioactivity can be demonstrated by its bioelectrocatalytic activity to the reduction of dissolved oxygen. The GOD/PDS/GC electrode displayed potential application for the fabrication of glucose biosensors with a linear glucose response up to 8mM in the presence of oxygen. Additionally, the biosensor based on the PDS nanoparticle modified electrode exhibited good stability and selectivity. The successful practice of using the PDS modified electrode for the direct electrochemical analysis of proteins and the bioelectrocatalytic activity of enzymes offers an efficient strategy and a new promising platform for the application of rare earth oxide materials in the field of electrochemical sensors.In the third part of this paper, phosphomolybdic heteropoly acid was adsorbed by electrostatic attraction glassy carbon on modified PDS. The formation of the film was studied. Cyclic voltammetry was used for the characterization and electrochemical properties of the films. Three stable and reversible redox couples were observed in 0.5 mol/L H2SO4 in the range of 0.8~ -0.2 V, which could be attributed to three electrochemical process of phosphomolybdic heteropoly acid. The obtained modified electrode has excellent electrocatalytic activity toward the NO2-,IO3-,BrO3-. The property of PDS makes it very useful in the electrochemical sensor material.