Electrochemiluminescence Sensor for Uric Acid Detection Using Natural Enzyme-Confined Nanozyme Cascade

The detection of metabolites, such as uric acid (UA), is crucial for diagnosing and monitoring various metabolic disorders. Herein, an electrochemiluminescence (ECL) sensor for uric acid (UA) detection was constructed via integrating a cascade of bioenzyme (urate oxidase [UOx]) and confined nanozyme reactions. Gold nanoparticles (AuNPs) were confined within amino-functionalized vertical mesoporous silica film (NH₂-VMSF) via electrochemical deposition. The NH₂-VMSF was synthesized on indium tin oxide (ITO) through electrochemical-assisted self-assembly (EASA) method. Amino groups on the NH₂-VMSF surface served as anchoring sites for AuNPs, which were electrochemically reduced and confined within the nanochannels. The confined AuNPs exhibited strong pseudo-peroxidase-like activity, boosting ECL response of luminol-H₂O₂. Compared to the NH₂-VMSF/ITO electrode, the AuNPs-deposited electrode produced a 3.4-fold increase in ECL intensity. Urate oxidase catalyzed the oxidation of uric acid, producing H₂O₂, which acted as a co-reactant for luminol, enabling indirect uric acid detection. The sensor demonstrated a detection range of 0.1-20 μM with a low limit of detection (LOD, 85 nM). The sensor was used for UA detection in complex biological samples (urine). The nanoconfined AuNPs provided a stable and effective environment for nanozyme-catalyzed reactions, ensuring high sensitivity and long-term stability.