Fabrication of reagentless glucose biosensors: A comparison of mono-enzyme GOD and bienzyme GOD–HRP systems

Glucose oxidase (GOD) and horseradish peroxidase (HRP), entrapped alone and simultaneously in silica sol–gel (SG) network on gold nanoparticles (GNPs) modified indium tin oxide (ITO) electrode, were used to fabricate mono-enzyme GOD and bienzyme GOD–HRP glucose biosensors. The optimal conditions for the construction and the analytical performances of the biosensors were studied and compared. The optimal GOD concentration in mixed solution for the mono-enzyme and bienzyme glucose biosensors was about 250 U/mL, and the optimal GOD/HRP ratio was approximately 2 for the bienzyme glucose biosensors. Amperometric response of glucose was evaluated by holding the biosensors at 0.1 V (versus SCE). The linear ranges of detection for glucose were between 0.05–4.0 mmol/L and 0.02–3.2 mmol/L, respectively. The sensitivity of the bienzyme glucose biosensor was approximately 2.4-fold higher than that of mono-enzyme glucose biosensor. Both glucose biosensors showed rapid response, high selectivity and long-term stability.