Direct and single-step sensing of primary ovarian cancers related glycosidases

High sensitive, accurate detection for tumor-associated overexpressed enzyme activity is highly significant for further understanding enzyme function, discovering potential drugs, and early diagnosis and prevention of diseases. In this work, we developed a facile, direct and single-step detection platform for primary ovarian cancers related glycosidase activity based on the inner filter effect (IFE) between glycosidase catalytic product and black phosphorus quantum dots (BPQDs). Highly fluorescent BPQDs were successfully synthesized from bulk black phosphorus by a simple liquid exfoliation method. Under the catalysis of β-galactosidase, p-nitrophenyl-β-D-galactopyranoside (PNPG) was transformed into pnitrophenol (PNP) and β-D-galactopyranoside. Meanwhile, the absorption of catalytic product PNP greatly overlapped with the excitation and emission spectra of fluorescent BPQDs, leading to the fluorescence quenching of BPQDs with a high quenching efficiency. The proposed sensing strategy provided a low detection limit of 0.76 U/L, which was 1-2 orders of magnitude lower than most unmodified sensing platforms. D-Galactal was selected as the inhibitor for β-galactosidase to further assess the feasibility of screening potential inhibitors. The fluorescence recovery of BPQDs suggests that the unmodified sensing platform is feasible to discover potential drugs of β-galactosidase. Our work paves a general way in the detection of glycosidase activity with fluorescent BPQDs, which can be promising for glycosidase-related disease diagnosis and pathophysiology elucidation.