Ratiometric fluorescence based on silver clusters and N, Fe doped carbon dots for determination of H2O2 and UA: N, Fe doped carbon dots as mimetic peroxidase

In this study, a dual-emission ratiometric fluorescent sensing system is developed for the analysis of H2O2 and uric acid (UA). This sensing system is based on N, Fe-doped carbon dots (N, Fe-CDs) and bovine serum albumin (BSA)-stabilized silver nanoclusters (BSA-Ag NCs) with peroxidase activity. By the catalysis of uriase, UA was oxidized by oxygen dissolved in the solution and H2O2 is produced. The carbon site with peroxidase activity can catalyze H2O2 to generate hydroxyl radicals, which etches to the BSA-Ag NCs. At the excitation wavelength of 390 nm, there were dual emission peaks at 450 nm and 650 nm. With increasing concentration of H2O2 or UA, the red fluorescence at 650 nm for BSA-Ag NCs decreases due to the etching of BSA-Ag NCs by hydroxyl radicals, while the blue fluorescence of N, Fe-CDs is restored. Based on the relationship between the fluorescence intensity ratio (I450/I650) to detect H2O2 and UA, the linear range of H2O2 was 0.6–100 μM with a detection limit of 0.30 μM (S/N = 3), while the linear range of UA was 0.8–133 μM with a detection limit of 0.49 μM (S/N = 3). Moreover, the present method was used for the analysis of UA in human urine with satisfactory accuracy as well as recovery. This ratiometric fluorescent approach can be used for analysis of UA and H2O2 for biomedical applications.