Electrodeposition of chitosan–ionic liquid–glucose oxidase biocomposite onto nano-gold electrode for amperometric glucose sensing

A sensitive glucose biosensor was fabricated by electrodepositing chitosan–ionic liquid–glucose oxidase biocomposite onto nano-gold electrode. First, nano-gold electrode was constructed by electrochemically depositing gold nanoparticles onto a flat gold electrode surface. Then the nano-gold electrode was immersed in the bath containing p-benzoquinone (BQ), chitosan (CS), glucose oxidase (GOD) and ionic liquid (IL) for electrodeposition of enzymatic electrode. The proton consumption during electroreduction of BQ increased the local solution pH near the electrode surface and led to the deposition of CS hydrogel on the electrode surface. Co-deposition of GOD and IL with the CS hydrogel was achieved. The proposed biosensor exhibited a fast amperometric response (<5 s) to glucose. Under the optimal conditions, the proposed biosensor exhibited a high current sensitivity (14.33 μA mM−1 cm−2), which was 2.8 times of the biosensor prepared by electrodepositing CS–IL–GOD biocomposite on flat gold electrode. The detection limit for glucose was 1.5 μM, which was 20-fold lower compared to the biosensor prepared on flat gold electrode. The linear range for glucose detection was wide from 3.0 μM to 9.0 mM. Moreover, the proposed biosensor exhibited high reproducibility, long-time storage stability and satisfactory anti-interference ability. The applicability of the proposed biosensor to serum samples analysis was also evaluated.