Silky CoO nanostructures for the selective and sensitive enzyme free sensing of uric acid.

In this study, simple, new and functional silky nanostructures of CoO are prepared by hydrothermal method. These nanostructures are successfully used for the enzyme free sensing of uric acid in 0.1 M phosphate buffer solution of pH 7.3. Physical characterization experiments were carried out to explore the morphology, composition and crystalline phase of the newly prepared CoO nanostructures. Scanning electron microscopy (SEM) shows a silk like morphology and energy dispersive spectroscopy (EDS) revealed the presence of Co and O as the main elements. Powder X-ray diffraction (XRD) demonstrates a cubic crystallography with well resolved diffraction patterns. The electrochemical activity of these silky CoO nanostructures was evaluated by cyclic voltammetry (CV) in a 0.1 M phosphate buffer solution at pH 7.3. The high purity and unique morphology of CoO shows a highly sensitive and selective response towards the non-enzymatic sensing of uric acid. This uric acid sensor exhibits a linear range of 0.5 mM to 3.5 mM uric acid and a 0.1 mM limit of detection. The anti-interference capability of this uric acid sensor was monitored in the presence of common interfering species. Furthermore, electrochemical impedance spectroscopy confirms a low charge transfer resistance value of 5.11 K Ω cm for silky CoO nanostructures which significantly supported the CV results. The proposed modified electrode is stable, selective and reproducible which confirms its possible practical use. Silky CoO nanostructures can be of great importance for diverse electrochemical applications due to their excellent electrochemical activity and large surface area.