CQPP

CQPP is a Fluorescent probe designed for monitoring polarity changes in the cellular microenvironment, including polarity tracking of lipid droplets/nuclei during ferroptosis. CQPP exhibits ratiometric fluorescence emission and fluorescence lifetime variations in response to polarity changes; a nonpolar environment stimulates fluorescence from the locally excited (LE) state, while a polar environment drives solvation relaxation to the intramolecular charge transfer (ICT) state, which attenuates the LE emission at ~470 nm and simultaneously enhances the ICT emission at ~670 nm. CQPP binds to intranuclear DNA through electrostatic interactions and hydrogen bonds in the DNA minor groove, which enhances its emission at ~670 nm and prolongs its fluorescence lifetime. CQPP can simultaneously target lipid droplets (green LE fluorescence) and the nucleus (red ICT fluorescence). The detection wavelengths of CQPP are Ex/Em = 405/470 nm and Ex/Em = 405/670 nm, and it also supports fluorescence lifetime imaging via 810 nm two-photon excitation .