Au-PDA@SiO₂ core-shell nanospheres decorated rGO modified electrode for electrochemical sensing of cefotaxime

In this work, we have successfully synthesized core-shell structured Au-PDA@SiO₂ nanospheres and decorated on reduced graphene oxide (rGO) modified glassy carbon electrode for the electrochemical detection of cefotaxime. The one-pot hydrothermal method was used to synthesis core-shell nanostructures by loading Au nanoparticles on polydopamine (PDA) coated SiO₂ nanospheres. The as-prepared Au-PDA@SiO₂ nanospheres were used to fabricate electrochemically reduced graphene oxide (rGO) modified glassy carbon electrode (Au-PDA@SiO₂/rGO/GCE) for electrochemical determination of cefotaxime. Scanning electron microscopy, powder x-ray diffraction, transmission electron microscopy, and Fourier-transform infrared spectroscopy were used to confirm the structure and morphology of the as-prepared nanospheres. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were performed for electrochemical characterizations different modified electrodes. It was revealed that the nanocomposite modified electrodes exhibited excellent electrochemical performances for electrooxidation of target analytes and could achieve ultra-sensitive detections. A linear relationship was observed between peak currents and concentrations in the ranges of 1.0 × 10^-9 to 5.0 × 10^-8 M (R² = 0.9877), and 1.0 × 10^-7 to 5.0 × 10^-6 M (R² = 0.9821) for cefotaxime with a detection limit (S/N = 3) of 1.0 × 10^-10 M. It can be deduced that the proposed sensor is suitable for the sensitive detection of cefotaxime in pharmaceutical samples.