Detecting uric acid base on the dual inner filter effect using BSA@Au nanoclusters as both peroxidase mimics and fluorescent reporters

Fluorescent bovine serum albumin-protected gold nanoclusters (BSA@Au NCs) can catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) to produce blue oxTMB for its peroxidase-like activity. The two absorption peaks of oxTMB overlapped with the excitation and emission peaks of BSA@Au NCs, respectively, causing efficient quenching on the fluorescence of BSA@Au NCs. The quenching mechanism can be attributed to the dual inner filter effect (IFE). Based on the dual IFE, BSA@Au NCs were utilized as both peroxidase mimics and fluorescent reporters for H₂O₂ detection and further for uric acid detection with uricase. Under optimal detection conditions, the method can be used to detect H₂O₂ ranging 0.50-50 μM with a detection limit of 0.44 μM and UA ranging 0.50-50 μM with a detection limit of 0.39 μM. The established method had been successfully utilized for the determination of UA in human urine, with massive potential in biomedical applications.