Design and synthesis of a library of BODIPY-based environmental polarity sensors utilizing photoinduced electron-transfer-controlled fluorescence ON/OFF switching

A study was conducted to systematically examine the mechanism of the solvent polarity dependence of the fluorescence ON/OFF threshold of the BODIPY (boron dipyrromethene) fluorophore and the role of photoinduced electron transfer (PeT). The findings revealed that polarity at the surface of albumin was found to be similar to that of acetone while the polarity of the internal membranes of HeLa cells was similar to that of dichloromethane.