Preparation and properties of a glucose biosensor based on an ionic liquid-functionalized graphene/carbon nanotube composite

Abstract A novel glucose biosensor was fabricated by loading a glassy carbon electrode with a 1-methyl imidazole based ionic liquid-functionalized graphene/carbon nanotubes(CNTs) composite, which was used to immobilize horse radish peroxidase (HRP) and glucose oxidase (GOD) for glucose detection. SEM, AFM and FTIR were used to investigate the microstructure and morphology of the electrode. The electrochemical performance of the electrode was investigated by cyclic voltammetry(CV) and electrochemical impedance spectroscopy. Results indicates that the electrode has excellent electrocatalytic activity towards glucose. The biosensor prepared at the optimal loading amount and ratio of HRP to GOD has a linear range of 0.004-5 mmol/L, a detection limit of 3.99×10−7mol/L and a sensitivity of 53.89 μA mmol/L−1cm−2 for glucose detection with an excellent stability and reproducibility. The excellent performance of the biosensor is ascribed to the stable three-dimensional structure, where graphene sheets provide a large surface area for immobilizing two enzymes and CNTs insert between graphene sheets to decrease electron transfer resistance.