title: ICPBC and C12-ICPBC: two new red emitting, fluorescent Ca2+ indicators excited with visible light.
abstract: Two new, visible-excited and red-emitting fluorescent Ca(2+) indicators were synthesized and the spectral profiles of their free and Ca(2+) bound forms were studied. The fluorescent properties of these probes are due to the extended conjugation of the chromeno[3',2':3,4]pyrido[1,2a][1,3]benzimidazole chromophore incorporated in their BAPTA-type, Ca(2+) chelating structure. The compounds, namely ICPBC and its N-dodecyl analog C12-ICPBC exhibit Ca(2+) dissociation constants of 7.7 and 18.0 microM, respectively. The fluorescence spectra of the probes showed a clear shift in excitation wavelength maxima upon Ca(2+) binding along with a large Stokes shift and changes in fluorescence intensity, indicating their potential use as Ca(2+) indicators. The ability of ICPBC to trace high calcium spikes was tested in the human HepG2 cell line with positive results.
authors.affiliation: Department of Chemistry, University of Crete, Heraklion, 71409 Crete, Greece.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Roussakis
authors.forename: Fotini
authors.initials: F
authors.lastname: Liepouri
authors.forename: Artemissia-Phoebe
authors.initials: AP
authors.lastname: Nifli
authors.forename: Elias
authors.initials: E
authors.lastname: Castanas
authors.forename: Todor G
authors.initials: TG
authors.lastname: Deligeorgiev
authors.forename: Haralambos E
authors.initials: HE
authors.lastname: Katerinopoulos
mesh_terms: D000465:Algorithms; D001562:Benzimidazoles / Q000138:chemical synthesis* / Q000737:chemistry; D001578:Benzopyrans / Q000138:chemical synthesis* / Q000737:chemistry; D002118:Calcium / Q000032:analysis*; D002460:Cell Line; D005456:Fluorescent Dyes / Q000138:chemical synthesis* / Q000737:chemistry; D006801:Humans; D007202:Indicators and Reagents / Q000138:chemical synthesis / Q000737:chemistry; D008027:Light; D018613:Microscopy, Confocal / Q000379:methods; D008856:Microscopy, Fluorescence
chemical_list: D001562:Benzimidazoles; D001578:Benzopyrans; C508761:C12-ICPBC compound; D005456:Fluorescent Dyes; C508760:ICPBC compound; D007202:Indicators and Reagents; D002118:Calcium