Direct voltammetric sensing of L-cysteine at pristine GaN nanowires electrode

The study demonstrates an electrochemical approach for direct sensing of L-Cysteine at gallium nitride nanowires (GaNNWs), a wide band gap semiconductor possessing 1-dimensional nanomaterial-specific high surface-sensitivity and unusually high surface-conductivity. Pristine GaNNWs can respond to L-Cysteine oxidation without any surface-modification: a unique advantage compared with other common electrodes. Cyclic voltammetric investigations on the effects of pH and potential-scan rate reveal an electrocatalytic oxidation of L-Cysteine controlled by the electroactive L-CyS(-) species. Advantages of direct L-Cysteine oxidation at surface-dominated GaNNWs electrodes can achieve an optimum sensitivity of 42 nA/μM with an experimental detection limit of 0.5 μM, over 0.5-75 μM dynamic range, under physiological condition (pH=7.4).