Electrochemical determination of l-Cysteine by an elbow shaped, Sb-doped ZnO nanowire-modified electrode

Elbow shaped Sb-doped ZnO nanowires (SZO NWs) have been synthesized via thermal evaporation and thoroughly characterized. A glassy carbon (GC) electrode was modified by these NWs for the determination of L-cystein (L-CySH). Detailed electrochemical measurements of the modified electrode towards L-CySH oxidation are investigated. The response current of L-CySH oxidation at the SZO/GC electrode is found to be much higher than that of the bare GC and ZnO/GC electrodes. This change in the electrochemical properties of the modified electrode is due to the reduction in band gap and an increased amount of deep-level defects in SZO NWs, which leads to a significant role in the L-CySH determination. The modified electrode exhibits a reproducible sensitivity of 400 nA μM^-1, within a response time of less than 6s, a detection limit of 0.025 μM and a linear range of 0.075 to 100 μM. Furthermore, the modified electrode shows high stability and good resistance to interference. Our investigation demonstrates that SZO NWs are very sensitive to L-CySH and can be employed in the development of biosensors for future biological and medical applications.