Non-enzymatic simultaneous detection of l-glutamic acid and uric acid using mesoporous Co3O4 nanosheets

Abstract

Cobalt oxide nanosheets (Co₃O₄ NSs) were synthesized by a facile wet-chemical technique at low-temperature in the alkaline phase. The Co₃O₄ NSs were characterized using various conventional methods, such as Fourier-transform infrared spectroscopy (FTIR), ultraviolet visible spectroscopy (UV/Vis), field emission scanning electron microscopy (FESEM) equipped with X-ray electron dispersive spectroscopy (XEDS), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET) studies, powder X-ray diffraction (XRD), etc. Simultaneously, two selective L-glutamic acid (L-GA) and uric acid (UA) biological sensors were obtained via the fabrication of a thin layer of NSs onto a glassy carbon electrode (GCE, surface area: 0.0316 cm²). Improved electrochemical performance such as higher sensitivity, linear dynamic range (LDR) and long term stability of the preferred L-GA and UA has been achieved using a reliable I–V method. The calibration curves of L-GA and UA are found to be linear (R² = 0.889 and 0.901) over a wide range of concentrations (0.1 nM to 0.1 M). Based on a signal-to-noise ratio of 3, the sensor sensitivity and limit of detection (LOD) of L-GA and UA were calculated to be 9.5 × 10⁻⁵ and 1.6 × 10⁻⁴ μA μM⁻¹ cm⁻², and 10.0 and 60.0 pM, respectively. The synthesis of Co₃O₄ NSs by a wet chemical route is an outstanding approach for the development of nanomaterial based biosensors to aid enzyme-free detection in healthcare fields. Finally, the proposed Co₃O₄ NSs sensor was applied in the selective detection of L-GA and UA simultaneously in real samples such as serum and urine and found to give acceptable and reasonable results.