Surface engineering of carbon dots for highly sensitive α-glucosidase assay and inhibition evaluation

Monitoring α-glucosidase (α-Glu) activity is of great significance for the early diagnosis of type II diabetes. Here the blue fluorescent carbon dots (CDs) were integrated with two different recognizing molecules, β-cyclodextrin and phenylboronic acid, for assembling a multifunctional CDs (mCDs) nanoplatform for sensitively analyzing α-Glu and its inhibitors. The hydrolyzed product of 4-nitrophenyl-α-d-glucopyranoside (α-Glu substrate), p-nitrophenol, could efficiently quench the fluorescence of mCDs due to its cooperative molecular recognition with β-cyclodextrin and phenylboronic acid. The mCDs could be utilized for the detection of α-Glu activity with the limit of detection of 0.030 U/L. Moreover, the present α-Glu detection platform revealed a high selectivity, and other natural enzymes showed scarcely any effect on the present mCDs system. The proposed method could be facilely used to screen α-Glu inhibitors with satisfying performance. The rational mCDs is expected to supplement more comprehensive biosensing platforms for highly sensitive and specific recognition of disease-relevant biomarkers with clinical importance.