A fluorescent light-up probe based on AIE and ESIPT processes for beta-galactosidase activity detection and visualization in living cells

摘要

A novel fluorescent probe SA-beta Gal is reported here with light-up response to beta-galactosidase. SA-beta Gal possesses the beta-galactopyranoside group to react with beta-galactosidase and releases the fluorescent salicylaldehyde azine with both aggregation induced emission (AIE) and excited-state intramolecular proton transfer (ESIPT) characteristics. The linear fluorescent response enables the in vitro quantification of beta-galactosidase activity in a range of 0-0.1 U mL(-1) with a detection limit of 0.014 U mL(-1). The probe exhibits significant advantages, such as no self-quenching at high concentrations, a large Stokes shift (190 nm) and high specificity to beta-galactosidase with an excellent light-up ratio of 820 fold. Moreover, thanks to its good retention in living cells, the application of SA-beta Gal for the imaging of cellular beta-galactosidase was also achieved with high contrast.