Amperometric hydrogen peroxide biosensor based on covalently immobilizing thionine as a mediator.

A novel amperometric hydrogen peroxide biosensor based on the immobilization of hemoglobin on the 2,6-pyridinedicarboxylic acid (PDC) polymer, thionine and nano-Au was successfully fabricated. In this strategy, PDC polymer acted as the matrices to covalently immobilize the thionine, and then hemoglobin was successfully adsorbed on the nano-Au which was electro-deposited on to thionine modified electrode surface. The preparation process of modified electrode was characterized with electrochemical impedance spectroscopy and atomic force microscope. The analytical performance of proposed biosensor toward H(2)O(2) was investigated by cyclic voltammetry and chronoamperometry. The resulted biosensor exhibited fast amperometric response (within 6 s) to H(2)O(2), and linear range was from 9.1 microM to 5.0 mM with the detection limit of 2.6 microM (S/N = 3). The apparent Michaelis-Menten constant (K(M)(app)) was evaluated to be 3.2 mM. Furthermore, the resulted biosensor showed good stability and reproducibility.