Electrochemical detection of diclofenac and clindamycin using ZnO nanorods/RGO nanocomposite modified electrode

A new electrochemical sensor based on electrochemically reduced graphene oxide (RGO) and zinc oxide (ZnO) nanorods was developed for the determination of the nonsteroidal anti-inflammatory drug (Diclofenac) and antibiotic drug (Clindamycin) for applications in human health monitoring. Graphene oxide (GO) and ZnO nanorods were synthesised by Hummer's and hydrothermal methods, respectively. The ZnO/GO composite (1 : 1 ratio) was prepared using the sonochemical method. As-prepared GO, ZnO, and ZnO/GO nanocomposite materials are characterised by UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), high-resolution scanning electron microscopy (HR-SEM), Energy dispersive spectroscopy (EDAX), Thermogravimetric analysis (TGA), Zeta potential/Dynamic light scattering (DLS), and Electrochemical impedance spectroscopy (EIS). In addition, the ZnO/GO nanocomposite film-coated electrode was reduced electrochemically to ZnO/RGO. The electrochemical reaction of the ZnO/RGO was investigated by using cyclic voltammetry (CV). The ZnO/RGO/GCE-based electrochemical sensor showed the lowest detection limits for diclofenac (DCF) and clindamycin (CMC) as 0.079 µM and 0.018 µM, respectively. The sensitivity of the sensor was 0.127 µA µM^-1 cm^-2 for DCF and 0.153 µA µM^-1 cm^-2 for CMC, and a linear response in the range of 0.5 to 85.0 µM for DCF and 0.05 to 36.50 µM for CMC was observed. The ZnO/RGO/GCE sensor was tested in a real sample of human urine and found a recovery range of 90.0% to 106.0%. Overall, the proposed dual electrochemical sensor can be used in real-world applications.