Fabrication and Application of CuO/ZnO/Rgo Nanocomposite Modified Pencil Graphite Electrodes for Urea and Uric Acid Biosensing in Uremic Samples

Abstract

Gout is a disease associated with defective metabolism of uric acid that also results in arthritis with chalkstone deposits on bones of the feet, causing acute painful episodes. Both gout and hyperuricemia are diseases linked with certain levels of uric acid in suffers and even some patients with renal diseases. With the relationship between serum uric acid and urea as biometabolites, it was necessary to examine their uremic contents as contributive factors to chronic gout. This study was necessary since early detection of urea and uric acid, even at very minute levels, in human blood may foster a better understanding of renal health, facilitate prompt gout diagnosis, and eventually promote healthy living. In the present study, CuO/ZnO/reduced graphene oxide (rGO) nanocomposite modified pencil graphite electrodes are fabricated and appropriately characterized using surface morphological techniques (e.g., atomic force microscopy and scanning electron microscopy) and electrochemical techniques (e.g., cyclic voltammetry and electrochemical impedance spectroscopy). These nanocomposites sensors acted as substrates for adsorbing and detecting of urea and uric acid. Results from this study revealed a fabrication process for making modified electrode-based sensors for effective and simultaneous detection of both biomarkers at exceptionally low limit of detection (LOD) in uremic samples. No matrix interferences were recorded in both plasma and serum test samples. The optimum concentrations of these nanocomposites on the biosensor surfaces significantly recorded detection limits at 1.80 × 10-9 M for urea and 2.69× 10-9 M for uric acid in plasma while levels of urea and uric acid stood at 2.06 × 10-9 and 3.10× 10-9 M, respectively, in serum samples. The efficacy of this biomarker detection protocol was also examined from pharmacokinetic studies for both substances in their standard solutions and spiked uremic samples. Prompt sensing of these kinds of metabolites as disease biomarkers at low LOD is important in the assessment of degrading health conditions of gout patients as well as in monitoring inherent concentration changes for potential treatments. Furthermore, this detection protocol may have a future in bioassay involving gout diagnosis in renal patients, assessment of gross renal health or even in-vitro and in-vivo applications for monitoring drug dosages. Keywords: Gout, Biosensing; Uric acid; Simultaneous detection; Disease biomarker; Limit of detection