Label free Electrochemical Biosensor using Zinc Oxide-Reduced Graphene Oxide Nanocomposite for Uric Acid Detection

We synthesized Zinc Oxide Nanoparticles (ZnONPs) and associated them with Reduced Graphene Oxides (rGO) to create rGO-ZnONCs using ultrasonication. The ZnONPs and rGO-ZnONCs nanocomposites have average diameters of approximately 29.11 nm and 12.5 nm, respectively. A set of characterization tools was used to examine the synthesized nanocomposites. The optical parameters were analyzed using ultraviolet-visible spectroscopy (UV-visible). Fourier Transform Infrared Spectroscopy (FT-IR) confirmed the chemical composition of the nanocomposites. The X-ray diffraction (P-XRD) pattern revealed the existing planes and their crystallized sizes. High-resolution Transmission Electron Microscopy (HR-TEM) provided detailed information about the nanocomposites' structure, size, and interplanar distances. Next, electrophoretic deposition techniques were used to deposit ZnONPs and rGO-ZnONCs nanocomposites onto Indium Tin Oxide (ITO) glass substrates. These fabricated material electrodes were further used to immobilize enzymes using physical and chemical methods. The newly fabricated UOx/ZnONPs/ITO and UOx/rGO-ZnONCs/ITO bioelectrodes showed a wide linear range from 0.005 to 1.0 mM, with limits of detection (LOD) of 0.13 µA/mM and 0.09 µA/mM, respectively. The UOx/ZnONPs/ITO bioelectrode exhibited a 25.98 µA/mM current. In comparison, the UOx/rGO-ZnONCs/ITO bioelectrode showed a higher current of 32.76 µA/mM, demonstrating its higher sensitivity and indicating the excellent electroactive nature of carbon-based materials.