Co-precipitation synthesis of cobalt doped ZnO nanoparticles: Characterization and their applications for biosensing and antibacterial studies

Abstract

A new modified sensor based on carbon paste electrode (CPE) was developed using cobalt doped ZnO (Co-ZnO) nanoparticles (NPs). In this work, we demonstrated the analytical behavior and applications of CPE modified with Co-ZnO/MCPE for the simultaneous determination of uric acid (UA) and adrenaline (AD) with highly selective and sensitive using voltammetric techniques. The synthesized Co-ZnO NPs were characterized by utilizing XRD, FTIR, FESEM with EDX, TEM, UV–Vis and photoluminescence spectroscopy. XRD suggests that the average size of these NPs was between 21 and 35 nm with a hexagonal wurtzite structure. Tauc plot exhibited that the optical energy bandgap of ZnO NPs gradually decreases with Co doping. Compared with undoped ZnO, Co-ZnO modified carbon paste electrode (Co-ZnO/MCPE) exhibits excellent electrochemical performance towards the oxidation of UA. Influencing factors, including scan rate, concentration, and pH values were optimized. Under the optimal condition, the Co-ZnO/MCPE responded to UA linearly with a detection limit of 3.37 µM and the fabricated sensor exposes diffusion-controlled electrode process. The developed Co-ZnO/MCPC has capable of determination of both UA and AD simultaneously with two different oxidation peaks. The sensitivity, long-term stability and reproducibility of the developed sensor were estimated. The bacterial efficiency of undoped and Co-ZnO NPs was inspected against gram-negative (Escherichia coli) and gram-positive (Enterococcus faecalis) bacteria.