A turn-on mode fluorescence detection of cholesterol based on calcein quenched by Co3O4 nanoclusters

Co3O4 nanoclusters (NCs) was prepared, and a novel method based on hydrogen peroxide (H2O2) mediated fluorescence recovery of calcein-Co3O4 NCs system for cholesterol detection was developed. The detection utilizes fluorescence quenching and recovery of calcein. In the absence of H2O2, the fluorescence of calcein is quenched by Co2+ ions on the surface of Co3O4 NCs. However, the fluorescence of calcein is restored in the presence of H2O2 as a result of the oxidation of Co2+ ions to Co3+ ions. Further investigation indicates tha Co3O4t there is a correlation between H2O2 concentration and fluorescence enhancement of calcein. Due to H2O2 being one of the products of cholesterol catalytic oxidation, a novel cholesterol fluorescence measurement method has been established, which can achieve sensitive detection of cholesterol in the range of 1.0–50 μM, with a limit of detection (LOD) as low as 0.48 μM. More importantly, the feasibility of the method was verified in human serum total cholesterol determination with satisfactory results, indicating its potential application in real sample analysis.