A label-free fluorescent sensor based on silicon quantum dots-MnO₂ nanosheets for the detection of α-glucosidase and...

α-Glucosidase and its inhibitors play a key role in diagnosis and treatment of diabetes. In the present work, we established a facile, sensitive and selective fluorescence method based on silicon quantum dots (SiQDs) and MnO₂ nanosheets for the determination of α-glucosidase and one of its inhibitors acarbose. The fluorescence of SiQDs was greatly quenched by MnO₂ nanosheets due to the inner filter effect. α-Glucosidase could easily catalyze the hydrolysis of l-ascorbic acid-2-O-α-d-glucopyranosyl (AAG) to produce ascorbic acid (AA), which could reduce MnO₂ nanosheets to Mn²⁺, resulting in dramatic recovery of the fluorescence of SiQDs. The proposed sensing platform could provide a good linear relationship between the fluorescence intensity of SiQDs and the concentration of α-glucosidase in the range of 0.02-2.5 U mL^-1 with a detection limit of 0.007 U mL^-1. In addition, the sensing platform could be used for α-glucosidase inhibition. Acarbose was one of the most common and typical inhibitors, and this sensing platform can be utilized to detect acarbose in the range of 1-1000 μM. The developed fluorescence method was successfully validated for the determination of α-glucosidase in human serum samples.