title: A polarity dependent fluorescence "switch" in live cells.
abstract: The spectroscopic properties, ultrafast kinetics and utilization of a photochromic molecule as a bi-stable fluorescing sensor of polarity in live cells are described. This molecule is a photochromic fulgimide, 2,3-dialkylidenesuccinimide, which emits fluorescence that can be switched optically on and off. The fluorescence intensity is a function of the polarity of the molecular environment, namely it fluoresces strongly when the molecule is in its polar isomeric structure form. We demonstrate that this molecule enters live cells without inducing damage, it binds primarily to internal membranous organelles (mitochondria) and its fluorescence can be switched optically "on" and "off" repeatedly while inside the living cell. A possible use as a bi-stable, on/off sensor is discussed.
authors.affiliation: Department of Biomedical Engineering, Beckman Laser Institute, University of California, 1002 Health Sciences Rd. East, Irvine, CA 92612, USA. mberns@laser.bli.uci.edu
authors.forename: Michael W
authors.initials: MW
authors.lastname: Berns
authors.forename: Tatiana
authors.initials: T
authors.lastname: Krasieva
authors.forename: Chung-Ho
authors.initials: CH
authors.lastname: Sun
authors.forename: Alexander
authors.initials: A
authors.lastname: Dvornikov
authors.forename: Peter M
authors.initials: PM
authors.lastname: Rentzepis
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D005453:Fluorescence; D005454:Fluorescence Polarization; D005456:Fluorescent Dyes / Q000737:chemistry / Q000528:radiation effects*; D007211:Indoles / Q000737:chemistry / Q000378:metabolism / Q000528:radiation effects*; D018613:Microscopy, Confocal; D008928:Mitochondria / Q000737:chemistry / Q000378:metabolism; D048328:Potoroidae; D011760:Pyrrolidinones / Q000737:chemistry / Q000378:metabolism / Q000528:radiation effects*; D012997:Solvents; D013053:Spectrophotometry; D013237:Stereoisomerism
chemical_list: C501934:2-(1-carboxy-3-isopropylidene-2,5-dioxopyrrolidin-4-ylidene)-1,3-dimethylindole; D005456:Fluorescent Dyes; D007211:Indoles; D011760:Pyrrolidinones; D012997:Solvents