Sensitive fluorimetric assays for α-glucosidase activity and inhibitor screening based on β-cyclodextrin-coated quantum dots

A fluorescence method was established for a alpha-glucosidase activity assay and inhibitor screening based on beta-cyclodextrin-coated quantum dots. p-Nitrophenol, the hydrolysis product of the alpha-glucosidase reaction, could quench the fluorescence of beta-cyclodextrin-coated quantum dots via an electron transfer process, leading to fluorescence turn-off, whereas the fluorescence of the system turned on in the presence of alpha-glucosidase inhibitors. Taking advantage of the excellent properties of quantum dots, this method provided a very simple, rapid and sensitive screening method for alpha-glucosidase inhibitors. Two alpha-glucosidase inhibitors, 2,4,6-tribromophenol and acarbose, were used to evaluate the feasibility of this screening model, and IC50 values of 24 mu M and 0.55 mM were obtained respectively, which were lower than those previously reported. The method may have potential application in screening a-glucosidase inhibitors. Copyright (C) 2015 John Wiley & Sons, Ltd.