Study Of Conductive-polymers And Carbon Nanotube Modified Biosensors

This paper studies biosensors for detecting the concentrations of glucose and uric acid in physiological solution, which is based on amperometric electrochemistry using modified screen-printed carbon paste electrodes.This paper presents a method to immobilize glucose oxidase and uricase in a polypyrrole film electropolymerized on the surface of screen-printed carbon paste electrodes. Pyrrole can be electropolymerized to polypyrrole in electropositive matrix under potentiostatic condition. Electronegative oxidase enzyme can be immobilized in the matrix due to the electrostatic effect. Based on a number of assays, the condition of electropolymerization has been optimized. Comparison experiments between the sensors with enzyme immobilized by electropolymerization and those with enzymes immobilized by adsorption have been done.The biosensors are prepared by immobilizing glucose oxidase or uricase on the surface of screen-printed carbon paste electrodes while potassium ferricyanide is employed as the electron mediator, which are so called "the third generation sensors". This paper shows that the carbon nanotube modification on the electrodes improves the sensitivities and response of the sensors to glucose and uric acid. Experimental results to compare the characters between the electrodes with and without carbon nanotube modification are illuminated. The advantage of carbon nanotube modification is analyzed based on electrochemical principle. Experimental results indicate that the interference of ascorbic acid in the determination of uric acid is neglectable.