A turn-on fluorescent probe for ultra-sensitive detection of β-galactosidase

The detection of beta-galactosidase is significant for identifying the occurrence of ovarian cancer and cellular senescence. Since the complexity and diversity of biological systems, fluorescent probes for biological detection are required to own good selectivity, high selectivity and strong anti-interference ability. To meet this challenge, we designed a turn-on fluorescent probe TC-gal by adjusting the effect of twisted intramolecular charge transfer (TICT) between intramolecular charge transfer (ICT) of the fluorophore for ultra-sensitive detecting of beta-galactosidase. The beta-galactosidase can specifically trigger an enhanced (more than 800 folds) light-up fluorescence of TC-gal due to attenuated TICT effect of tetraphenylethylene part and increased ICT effect induced by electron donating effect of generated hydroxyl. Such turn-on fluorescence selectively triggered by beta-galactosidase endows probe TC-gal with low background fluorescence and high signal-to-noise ratio. It is demonstrated that designed TC-gal exhibits high selectivity, ultra-high sensitivity (LOD = 8.4 x 10(-5) U/mL) and strong affinity (K-m = 18.4 pM) to beta-galactosidase in buffer solution with good anti-interference ability to other biological analytes. Furthermore, biocompatible probe TC-gal is successfully applied to detect endogenous beta-galactosidase in ovarian cancer cells and distinguish senescent cells. We anticipate this work can inspire the generation of superior fluorescent biosensors for biological and medical application.

Automated summary

The designed fluorescent probe TC-gal shows high selectivity and ultra-high sensitivity for detecting beta-galactosidase, with strong anti-interference ability to other biological analytes. By adjusting the intramolecular charge transfer effect, the probe achieves specific turn-on fluorescence triggered by beta-galactosidase.