New method for in situ assay of α-glucosidase activity and the inhibitor screening through enzyme substrate mediated DNA hybridization chain reaction
A new strategy has been proposed for in situ analysis of α-glucosidase (α-Glu) based on small molecule mediated DNA hybridization chain reaction (HCR) in this work. As an important digestion enzyme, α-Glu can catalyze the hydrolysis of the substrate, para-aminophenyl-α-D-glucopyranoside (pAPG), into para-aminopheny (pAP) and α-D-glucopyranoside. Among them, pAPG with cis-diols groups, can coordinate with boronic acid tagged initiation chain so as to drive HCR around assembly magnetic nanospheres (AMNSs). Nevertheless, the product of the catalytic reaction, pAP, has no capability for capturing boronic acid tagged initiation chain onto the surface of AMNSs, resulting in no occurrence of HCR. So α-Glu activity correlates with the extent of HCR around AMNSs and it can be tested in situ in cell medium with the aid of magnet. The enzyme activity has been analyzed in the wide linear range from 0.4 U/mL to 1.7 U/mL with the lowest detection limit of 0.023 U/mL. Furthermore, the established method can also be successfully utilized for in situ evaluation of enzyme inhibitors including gallic acid and quercetin. This study may provide a new insight for development of new method for in situ analysis of α-Glu in cell medium.