Hantzsch ester modified asymmetric BODIPY probe with ultra-high sensitivity for ultra-fast detection of endogenous hypochlorite in living cells

Hypochlorite (ClO - ) is an important reactive oxygen species produced by the immune system to fight off invading pathogens, but its over-expression can interfere with normal physiological process and induce serious diseases. Although a variety of molecular probes have been reported for detecting ClO - , the development of advanced fluorescent tools with faster response and higher sensitivity to precisely monitor ClO - remains a challenge. In this work, two Hantzsch ester (a derivative of 1,4-dihydropyridine) derived fluorescent probes MeDHP-BCl and MeDHP-PhBCl were constructed based on asymmetric BODIPY-matrix. These probes exhibit significant fluo-rescence turn-on in the ultra-sensitive (detection limit < 1 nM) and ultra-fast response (≤ 5 s) to ClO - , the reaction has determined to be a highly selective N-Chlorination of Hantzsch ester which cannot be activated by various common bioactive species, including nitric ox-ide (NO) that could oxidize Hantzsch ester under aerobic physiological conditions in most reports. MeDHP-PhBCl possess a relatively longer fluorescence emission wavelength and higher quantum yield after activation, while more notably, MeDHP-BCl displayed lower cytotoxicity and more remarkable fluorescence increasement in the response to ClO - , enabling selective and precise visualization of endogenous ClO - over-expression in living RAW264.7 cells.