Colorimetric detection of α-glucosidase activity based on the etching of gold nanorods and its application to screen anti-diabetic drugs

An ultrasensitive colorimetric method for alpha-glucosidase sensing based on iodine-mediated etching of gold nanorods (AuNRs) was developed. In this method, 2-O-alpha-D-glucopyranosyl-L-ascorbic acid (AA-2G) was used as an enzymatic substrate. The hydrolysate ascorbic acid in situ reduced KIO3 to I-2, which subsequently etched the AuNRs. A blue-shift of the localized surface plasmon resonance (LSPR) absorption of AuNRs was clearly observed by UV-vis spectroscopy and reflected with visual color changes. The shift showed a good linear relationship with the concentration of alpha-glucosidase during 2.5-45 U/L and a low alpha-glucosidase detection limit of 0.5 U/L was provided. This strategy was featured with low cost, simplicity, excellent sensitivity, high selectivity and successfully applied in the alpha-glucosidase inhibitor screening with Chinese Wolfberries as candidates.