The direct electron transfer of glucose oxidase and glucose biosensor based on carbon nanotubes/chitosan matrix

The glucose oxidase (GOD) is entrapped in the composite of carbon nanotubes/chitosan and direct electron transfer reaction between GOD and electrode takes place. The electron transfer rate of GOD is greatly enhanced to 7.73 s^-1 in the system, which is more than one-fold higher than that of flavin adenine dinucleotide adsorbed on the carbon nanotubes (3.1 s ^-1). This maybe results from the conformational change of GOD in the microenvironment enabling the accessibility of active site for GOD to the electrode. Additionally, the bioactivity of GOD modified in the composite on electrode surface is kept. So as-prepared electrode can be used as a glucose biosensor exhibiting higher sensitivity (0.52 μA mM^-1) and better stability. The facile procedure of immobilizing GOD will promote the developments of electrochemical research for protein, biosensors and other bioelectrochmical devices.