Fast Response Amperometric Biosensor for H2O2 Detection Based on Horseradish-Peroxidase/Titania-Nanowires/Chitosan Modified Glassy Carbon Electrode

A novel amperometric biosensor of H2O2 with very short response time was developed based on the efficient immobilization of horseradish peroxidase and titania-nanowires on a glassy carbon electrode by chitosan. The morphology of titania-nanowires, electrochemical properties and bioelectrocatalytic reactivity of horseradish-peroxidase/titania-nanowires/chitosan/glassy carbon electrode were fully investigated. In all the electrochemical experiments, hydroquinone (1 mM) was used as a free diffusing mediator to assure the electrical contact between horseradish peroxidase and the glassy carbon electrode. The experimental parameters, such as the applied potential of the working electrode, temperature and pH of phosphate buffer solutions, were optimized for best analytical performance. The rapid response of the biosensor to H2O2 may be attributed to the high permeability of enzymatic matrix. The linear range of the biosensor is from 0.004 mM to 1.15 mM. The sensitivity of the biosensor to H2O2 was calculated to be 124 mu A mM(-1) cm(-2) and the detection limit was calculated as 0.32 mu M based on signal/noise = 3 with a correlation coefficient of 0.99996. The apparent activation energy of the enzyme electrode reaction and apparent Michaelis-Menten constant were also investigated. This kind of biosensor with fast response, low applied potential and high sensitivity would be promising for the online determination of H2O2.