Regulate properties of glucose oxidase biosensors through pore sizes of TiO₂ nanotube arrays

Highly ordered TiO₂ nanotube arrays (TNA) with controlled pore sizes in a series of 21, 62, 83 and 102 nm were synthesized using constant current oxidization method. Glucose oxidases (GOx) were immobilized on TNA by physical adsorption, and the GOx activities on TNA were investigated by cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy. All immobilized GOx had good oxidizing activities in glucose solution and GOx on 83 nm-pore-sized TNA showed the best sensibility of 27.2 μA·(mmol·L^-1)^-1·cm^-2, which was probably due to a combination effect of reduced diffusion resistance and small Michaelis constant of the immobilized GOx. The experimental results had demonstrated that controlling pore sizes of TNA could effectively tune sensitivity of glucose biosensors.