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).