In vivo ratiometric tracking of endogenous β-galactosidase activity using an activatable near-infrared fluorescent probe

Herein, we developed a dual-channel and light-up near-infrared fluorescent probe for ratiometric sensing of beta-galactosidase (beta-gal) activity. The well-designed probe, which shows ratiometric optical response with a significant red-shift (from 575 nm to 730 nm), was successfully applied to detect endogenous beta-gal activity in SKOV-3 cells and tumor-bearing mice.