Detection of uric acid using colorimetric method based on iron-doped single-atom catalyst with peroxidase activity

Single-atom catalysts (SACs) have garnered considerable attention owing to their impeccable catalytic activity and unique ability to elucidate the active site. In this work, we synthesized iron-doped single-atom catalysts (Fe SACs) via a soft-template sacrificial approach, which exhibited peroxidase activity. Further investigations revealed that Fe SACs were capable of catalyzing the generation of highly reactive hydroxyl radicals (•OH) from hydrogen peroxide (H2O2), which facilitated the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) to oxTMB, resulting in a discernible color change from colorless to blue. According to the exceptional peroxidase activity of Fe SACs, we designed and fabricated a colorimetric sensor by combining uricase and TMB, achieving highly sensitive and selective detection of uric acid over a wide range of concentrations (0.1–50 μM), with a low detection limit of 0.039 μM (3σ/k). Finally, we demonstrated the feasibility of our sensor in detecting uric acid in real human urine samples, yielding satisfactory recoveries and low relative standard deviations.