Sensitive and Selective Electrochemical Determination of L-Cysteine Based on Cerium Oxide Nanofibers Modified Screen Printed Carbon Electrode

A novel L-cysteine (CysH) electrochemical sensor based on CeO₂ nanofibers (NFs) modified screen printed carbon electrodes (SPCEs) was developed. The morphology and the structure of the as-prepared CeO₂ NFs were first characterized using scanning electron microscopy (SEM) and X-ray diffraction pattern (XRD), respectively. The electrochemical and electrocatalytic performances of the CeO₂ NFs modified SPCEs were then evaluated using cyclic voltammetry and amperometry. Experimental results showed that the CeO₂ NFs modified SPCEs possess excellent electrocatalytic activity toward the detection of CysH. Specifically, the developed electrochemical sensor demonstrated a high sensitivity of 120 μA mM⁻¹ cm⁻², a low detection limit of 20 nM (signal to noise ratio of 3) and a wide linear range up to 200 μM for the determination of CysH, which are among the best values reported in literature. In addition, good selectivity and outstanding intra- and inter-electrode reproducibility have also been observed. Furthermore, the developed CysH sensor was applied to detect CysH spiked into human serum samples with remarkable accuracy. All these features indicate that CeO₂ NFs hold great promise in the development of high performance electrochemical sensor for CysH.