In situ formation of fluorescent non-conjugated polymer dots for α-glucosidase activity assay and inhibitor screening.

A novel and facile fluorescence turn-on assay for detecting α-glucosidase (α-Glu) activity and screening inhibitors is reported. This assay exploits α-Glu-catalyzed hydrolysis of L-ascorbic acid-2-O-α-D-glucopyranosyl (AA2G) to release ascorbic acid (AA), triggering an in situ fluorogenic reaction with N-methylethylenediamine (N-MEDA) that generates non-conjugated polymer dots (NCPDs). These NCPDs emit blue fluorescence at 425 nm upon excitation at 350 nm, and the fluorescence intensity increases proportionally with the concentration of α-Glu, enabling quantitative detection of enzymatic activity. The fluorescent assay demonstrates a linear response ranging from 0.01 to 10 U/mL and achieves a low detection limit of 0.0034 U/mL, surpassing most existing methods in sensitivity and width of linear range. In addition, the proposed method has been successfully applied to screen α-Glu inhibitors (AGIs) and determine α-Glu activity in real samples, yielding satisfying results. This work introduces a robust analytical framework and promising approach for clinical diagnosis and anti-diabetic drug discovery.