title: Design and synthesis of a library of BODIPY-based environmental polarity sensors utilizing photoinduced electron-transfer-controlled fluorescence ON/OFF switching.
abstract: We systematically examined 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). In a series of BODIPY derivatives with variously substituted benzene moieties at the 8-position, the oxidation potential of the benzene moiety became more positive and the reduction potential of the BODIPY fluorophore became more negative as the solvent polarity was decreased; consequently, the free energy change of PeT from the benzene moiety becomes larger in a more nonpolar environment. Utilizing this finding, we designed and synthesized a library of probes in which the threshold of fluorescence ON/OFF switching corresponds to different levels of solvent polarity. These environment-sensitive probes were used to examine bovine serum albumin (BSA) and living cells. The polarity at the surface of albumin was concluded to be similar to that of acetone, while the polarity of the internal membranes of HeLa cells was similar to that of dichloromethane.
authors.affiliation: Graduate School of Pharmaceutical Sciences, the University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Hisato
authors.initials: H
authors.lastname: Sunahara
authors.forename: Yasuteru
authors.initials: Y
authors.lastname: Urano
authors.forename: Hirotatsu
authors.initials: H
authors.lastname: Kojima
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Nagano
mesh_terms: D015374:Biosensing Techniques; D001896:Boron Compounds / Q000737:chemistry*; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D004563:Electrochemistry; D005456:Fluorescent Dyes / Q000737:chemistry*; D006367:HeLa Cells; D006586:Hexanes / Q000737:chemistry; D006801:Humans; D007202:Indicators and Reagents; D009682:Magnetic Resonance Spectroscopy; D018613:Microscopy, Confocal; D010084:Oxidation-Reduction; D012710:Serum Albumin, Bovine / Q000737:chemistry; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D013499:Surface Properties; D013816:Thermodynamics
chemical_list: C095489:4,4-difluoro-4-bora-3a,4a-diaza-s-indacene; D001896:Boron Compounds; D005456:Fluorescent Dyes; D006586:Hexanes; D007202:Indicators and Reagents; D012710:Serum Albumin, Bovine