Peroxidase Mimic Activities of Copper Selenide (CuSe) Nanoplates for Sensing H₂O₂ and L-Cysteine

Compared with natural enzymes, artificial mimic enzymes have been widely studied for their high stability and cost effectiveness. In this study, CuSe nanoplates as a simulated enzyme which does not contain precious metals, has peroxidase activity. CuSe nanoplates were prepared and characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray energy dispersive spectrometer (EDS). Kinetic studies show that CuSe nanoplates exhibits a higher affinity for 3,3',5,5'-teramethylbenzidine (TMB) than horseradish peroxidase (HRP). The rapid colorimetric determination of H₂O₂ and L-cysteine were developed based on the catalytic efficiency. The linear range of detection for H₂O₂ is 5.0×10^-6~8.0×10^-5 M, and the detection limit is 2.9×10^-6 M, while the relative standard error is less than 5%. In addition, L-cysteine was detected with a detection limit of 0.2×10^-6 M. The good selectivity of the determination to H₂O₂ and L-cysteine in aqueous solution was also achieved. CuSe nanoplates as a simulated enzyme for sensor applications would be used in environmental monitoring and biomedical analysis.