A ratiometric fluorescence platform based on WS QDs/CoOOH nanosheet system for α-glucosidase activity detection.

In this study, we have constructed a ratiometric fluorescence sensor for sensitive sensing of α-glucosidase activity based on WS QDs/ CoOOH nanosheet system. In this system, as an oxidase-imimicking nanomaterial, CoOOH nanosheet could convert o-phenylenediamine into 2,3-diaminophenazine (DAP), which had a high fluorescence emission at 575 nm. The DAP subsequently could quench the fluorescence of WS QDs via the inner filter effect (IFE). L-Ascorbic acid-2-O-α-D-glucopyranose could be hydrolyzed by α-glucosidase to yield ascorbic acid. CoOOH nanosheet can be converted to Co ions by ascorbic acid, leading to the fluorescence decrease of DAP and the fluorescence recovery of WS QDs. Therefore, a novel ratio fluorescence sensing strategy was established for α-glucosidase detection based on WS QDs/CoOOH nanosheet system. This WS QDs/CoOOH nanosheet system has a low detection limit of 0.009 U/mL for α-Glu assay. The proposed strategy succeeded in detecting α-Glu in human serum samples.