Ultrasensitive determination of α-glucosidase activity using CoOOH nanozymes and its application to inhibitor screening

In this work, a novel method for the colorimetric sensing of alpha-glucosidase (alpha-Glu) activity was developed based on CoOOH nanoflakes (NFs), which exhibit efficient oxidase-mimicking activity. Colorless 3,3 ',5,5 '-tetramethylbenzidine (TMB) can be oxidized by CoOOH NFs into blue-colored oxidized TMB (oxTMB) in the absence of H2O2. l-Ascorbic acid-2-O-alpha-d-glucopyranose (AAG) can be hydrolysed by alpha-glucosidase to produce ascorbic acid, resulting in a significant decrease of catalytic activity of CoOOH NFs. Thus, a colorimetric alpha-glucosidase activity detection method was designed with a limit of detection of 0.0048 U mL(-1). Furthermore, the designed sensing platform exhibits favorable applicability for the alpha-glucosidase (alpha-Glu) activity assay in real samples. Meanwhile, this method can be expanded to study the inhibitors of alpha-Glu. Finally, the as-proposed method combined with a smartphone would be a color recognizer, which was successfully applied for the determination of alpha-Glu activity in human serum samples.