Ionic liquid-capped silver-zinc oxide@activated carbon: A Powerful nanocomposite for colorimetric uric acid detection

Abstract

Abnormal levels of uric acid in the human body lead to several diseases such as gout, diabetes, renal impairment, cardiovascular problems, etc. It is imperative to develop an easy-to-use and low-cost sensing platform. The present work reports on a non-enzymatic colorimetric sensor based on the peroxidase-like activity of ionic liquid-capped silver-zinc oxide-doped activated carbon (IL/Ag-ZnO@AC) for the detection of uric acid. The prepared nanocomposite was characterized by various spectroscopic techniques. The prepared nanozyme catalyzed the oxidation of the chromogenic substrate TMB (3,3′,5,5′-tetramethylbenzidine). Based on the redox chemistry of uric acid, it inhibited the peroxidase-like activity of the proposed nanozyme with a visible colorimetric change. Subsequently, various parameters such as time, pH, H₂O₂, and the amount of the nanozyme as well as TMB were optimized. The proposed assay showed linear detection of uric acid in the range of 0.5–180 μM. Other parameters, such as the limit of detection, limit of quantification, and R² were computed to be 0.13 μM, 0.45 μM, and 0.999, respectively. Alongside its sensitivity, the developed assay was found to be highly selective in the presence of various potential interfering species. The proposed assay was successfully employed for the detection of uric acid in real samples under optimum experimental conditions. The proposed nanozyme has the potential to translate into a useful laboratory tool that can routinely be used for the sensing of uric acid in various diseases.