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

Co 3 O 4 nanoclusters (NCs) was prepared, and a novel method based on hydrogen peroxide (H 2 O 2 ) mediated fluorescence recovery of calcein-Co 3 O 4 NCs system for cholesterol detection was developed. The detection utilizes fluorescence quenching and recovery of calcein. In the absence of H 2 O 2 , the fluorescence of calcein is quenched by Co 2+ ions on the surface of Co 3 O 4 NCs. However, the fluorescence of calcein is restored in the presence of H 2 O 2 as a result of the oxidation of Co 2+ ions to Co 3+ ions. Further investigation indicates tha Co 3 O 4 t there is a correlation between H 2 O 2 concentration and fluorescence enhancement of calcein. Due to H 2 O 2 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.