An off-on fluorescence method for acid phosphatase assay based on the inner filter effect of MnO2 nanosheets on vitamin B2.

[Display omitted] • The fluorescence of VB 2 quenched by MnO 2 NSs was revealed. • VB 2 -MnO 2 NSs could be used as a probe for acid phosphatase fluorescence detection. • The method exhibited excellent sensitivity and high selectivity. Fluorescence analysis has attracted much attention due to its rapidity and sensitivity. The present work describes a novel fluorescence detection method for acid phosphatase (ACP) on the basis of inner-filter effect (IFE), where MnO 2 nanosheets (MnO 2 NSs) and vitamin B 2 (VB 2) are served as absorbers and fluorophores, respectively. In the absence of ACP, the absorption band of MnO 2 NSs overlaps well with the excitation band of VB 2 , resulting in effective IFE and inhibition of VB 2 fluorescence. In the presence of ACP, 2-phospho-L-ascorbic acid trisodium salt (AAP) is hydrolyzed to generate ascorbic acid (AA), which efficiently trigger the reduction of MnO 2 NSs into Mn2+ ions, causing the weakening of the MnO 2 NSs absorption band and the recovery of VB 2 fluorescence. Further investigation indicates that the fluorescence recovery degree of VB 2 increases with the increase of ACP concentration. Under selected experimental conditions, the proposed method can achieve sensitive detection of ACP in the ranges of 0.5–4.0 mU/mL and 4.0–15 mU/mL along with a limit of detection (LOD) as low as 0.14 mU/mL. Finally, this method was successfully applied for the detection of ACP in human serum samples with satisfactory recoveries in the range of 95.0 %-108 %. [ABSTRACT FROM AUTHOR]