A colorimetric sensing strategy based on chitosan-stabilized platinum nanoparticles for quick detection of α-glucosidase activity and inhibitor screening

alpha-Glucosidase (alpha-Glu) is implicated in the progression and pathogenesis of type II diabetes (T2D). In this study, we developed a rapid colorimetric technique using platinum nanoparticles stabilized by chitosan (Ch-PtNPs) to detect alpha-Glu activity and its inhibitor. The Ch-PtNPs facilitate the conversion of 3,3 ',5,5 '-tetramethylbenzidine (TMB) into oxidized TMB (oxTMB) in the presence of dissolved O-2. The catalytic hydrolysis of 2-O-alpha-D-glucopyranosyl-L-ascorbic acid (AA-2G) by alpha-Glu produces ascorbic acid (AA), which reduces oxTMB to TMB, leading to the fading of the blue color. However, the presence of alpha-Glu inhibitors (AGIs) hinders the generation of AA, allowing Ch-PtNPs to re-oxidize colorless TMB back to blue oxTMB. This unique phenomenon enables the colorimetric detection of alpha-Glu activity and AGIs. The linear range for alpha-Glu was found to be 0.1-1.0 U mL(-1) and the detection limit was 0.026 U mL(-1). Additionally, the half-maximal inhibition value (IC50) for acarbose, an alpha-Glu inhibitor, was calculated to be 0.4769 mM. Excitingly, this sensing platform successfully detected alpha-Glu activity in human serum samples and effectively screened AGIs. These promising findings highlight the potential application of the proposed strategy in clinical diabetes diagnosis and drug discovery.