Highly selective and sensitive uric acid sensor based on a self-assembled CdS/CdIn₂S₄ heterojunction

Uric acid (UA) detection plays a crucial role in the early diagnosis and treatment of diseases linked with hypo-/hyper-uricemia. Electrochemical sensing technology has attracted widespread attention due to its fast response, high sensitivity, portability and ease of operation. However, regular electrochemical UA sensors remarkably suffer from unfavorable selectivity, high cost, complexity of fabrication, and over-reliance on blood sampling. Herein, we present a hetero-structured CdS/CdIn₂S₄-modified screen-printed carbon electrode (SPCE) capable of achieving accessible and cost-effective UA determination via a facile hydrothermal self-assembly method, which enhances electrocatalytic activity through optimized band structures and abundant surface sites. Benefiting from the synergy of componential optimization and heterojunction design, the CdS/CdIn₂S₄/SPCE-based electrochemical UA sensor (CEUS) achieves a high sensitivity of 717.5 μA mM^-1 cm^-2, high selectivity, a wide linear range of 0.5-1000 μM and a low detection limit (LOD) of 0.12 μM. Density functional theory (DFT) calculations reveal that the heterojunction interface facilitates electron transfer and promotes hydroxyl radical generation to enhance UA oxidation. Furthermore, food hygiene inspection and gout monitoring are accomplished by probing the UA level in both fish foods and biological fluids, including serum, urine and sweat, obtaining satisfactory accuracy and anti-interference traits. This work provides a promising avenue for the development of ultrasensitive wearable nonenzymatic sweat biosensors for personalized health assessment and food-freshness monitoring.