Direct electrochemistry of glucose oxidase immobilized on a hexagonal mesoporous silica-MCM-41 matrix

The direct electrochemistry of glucose oxidase (GOD) immobilized on a hexagonal mesoporous silica modified glassy carbon electrode was investigated. The adsorbed GOD displayed a pair of redox peaks with a formal potential of - 417 mV in 0.1 M pH 6.1 phosphate buffer solution (PBS). The response showed a diffusion-controlled electrode process with a two-electron transfer coupled with a two-proton transfer reaction process. GOD immobilized on a hexagonal mesoporous silica retained its bioactivity and stability. In addition, the immobilized GOD could electrocatalyze the oxidation of glucose to gluconlactone by taking ferrocene monocarboxylic acid (FMCA) as a mediator in N₂ saturated solutions, indicating that the electrode may have the potential application in biosensors to analyze glucose. The sensor could exclude the interference of commonly coexisted uric acid, p-acetaminophenol and ascorbic acid and diagnose diabetes very fast and sensitively. This work demonstrated that the mesoporous silica provided a novel matrix for protein immobilization and the construction of biosensors.