Single-atom catalysts for electrochemical sensing of dopamine, uric acid, and ascorbic acid: from active-site structure to sensing performance.

Dopamine (DA), uric acid (UA), and ascorbic acid (AA) are important biomarkers whose selective and simultaneous electrochemical determination remains challenging because of their coexistence in biological matrices and overlapping redox responses. Conventional electrode materials often contain heterogeneous and incompletely utilized active sites, limiting precise control over analyte adsorption and electrocatalytic reactions. Single-atom catalysts (SACs) offer atomically defined active sites, high metal utilization, and tunable coordination and electronic structures, providing opportunities to regulate sensing reactions at the atomic level. This Review critically examines SAC-based electrochemical sensing of DA, UA, and AA from a structure-performance perspective. Particular emphasis is placed on how atomic dispersion, coordination environment, metal-support interactions, and electronic structure govern analyte adsorption, reaction energetics, electron-transfer kinetics, selectivity, and analytical response. Representative applications in individual and simultaneous detection are discussed to extract key design principles. Finally, remaining challenges and emerging opportunities in operando characterization, computationally assisted catalyst design, scalable synthesis, and wearable sensing are outlined.