Non-enzymatic glucose detection using nitrogen-doped diamond-like carbon electrodes modified with gold nanoclusters*

Highly sensitive electrochemical electrodes for glucose detection were developed by using Au nanoclusters (NCs) to modify nitrogen-doped diamond-like carbon thin films (DLC:N/Au). The DLC:N/Au electrodes were prepared with a filtered cathodic vacuum arc process followed by electrodeposition and characterized by X-ray photoelectron spectroscopy, Raman spectroscopy, and scanning electron microscopy. The size of the Au NCs covered by Au oxide ranged between 10 and 70 nm with a density of 108–109 clusters per cm2. Glucose oxidation at the DLC:N/Au electrodes started from about –0.5 V due to the high catalytic activities of the Au NCs in NaOH solutions, and the catalytic ability of the electrodes depended on the amount of Au NCs deposited on the electrode surfaces. A linear detection range of glucose with the DLC:N/Au electrodes was identified from about 0.25 to 30 mM (covering blood glucose levels in diabetic patients) with a detection limit of 60 μM. The experimental results showed that the non-enzymatic glucose sensors based on the DLC:N/Au electrodes had high sensitivity and good reproducibility and stability.