A novel two-photon ratiometric fluorescent probe platform was developed using a FRET strategy.
A FRET-based two-photon ratiometric fluorescent probe NRLys was developed to monitor pH change in lysosome.
NRLys possesses two well-resolved emission peaks separated by 60 nm.
The NRLys shows high ratiometric imaging resolution and deep-tissue imaging depth of over 180 μm.