The Study Of A Novel Biosensor Based On Glucose Oxidase

Be of an important enzyme,glucose oxidase (GOD) has good electrocatalytic abilityand high selectivity to glucose.The research of electrochemistry of GOD has a vitalsignificance in life sciences.By combining self-assembled monolayers (SAMs),nanotechnology and sol-gel technology,a novel GOD biosensor was developed using aone-step method which simultaneously immobilized GOD and gold nanoparticles inthree silica sol-gel net on the surface of prepared gold electrodes.The preparationconditions were optimized.The biosensor was prepared under the optimized conditionsand the direct electron transfer between the active center of enzyme and electrode surfacewas realized.A pair of well-defined redox peak was observed at the enzyme electrode incyclic voltammogram.The current ration of the cathodic peak current to the anodic one isnearly 1 and the separation between the anodic and cathodic peak potentials(△E_p=E_pa-E_pc=0.21 V at 100mV s^-1) indicate that the electrode process of GOD isquasi-reversible.The formal potential E^0',calculated according to average of anodic andcathodic peak potentials,is 110 mV versus SCE.The heterogeneous electron transfer rateconstant was evaluated to be about 2.9 S^-1.The chemical research shows that the enzymeimmobilized on the electrode surface can display an excellent electrocatalytic response tothe reduction of glucose.The calibration range of glucose was from 10 to 130μmol L^-1 anda detection limit of 3μmol L^-1 at a signal-to-noise ratio of 3.The K_M^app value of GODimmobilized on the electrode surface was found to be 9.8 mmol L^-1.The biosensorexhibited high sensitivity,rapid response.It was found the response current to glucosedecreased about 8% after storage at 4℃for 100 days.This proposed method is simple andeasy to operate,and it can be used for other enzymes and proteins to obtain the directelectron transfer.