Chloride-sensitive fluorescent indicators.
Three fluorescent halide-sensitive quinolinium dyes have been produced by the reaction of the 6-methylquinoline heterocyclic nitrogen base with methyl bromide, methyl iodide, and 3-bromo-1-propanol. The quaternary salts, unlike the precursor molecule, are readily water soluble and the fluorescence intensity of these salts is reduced in the presence of aqueous chloride, bromide, and iodide ions, allowing halide solution concentrations to be determined using well-known Stern-Volmer kinetics. One of the dyes, dye 1, has a chloride Stern-Volmer constant of 255 mol(-1) dm(3) which is more than twice that of SPQ [6-methoxy-N-(3-sulfopropyl)quinolinium] used in recent physiological measurements to measure intracellular chloride levels. The dyes have been characterized using steady-state fluorescence spectroscopy and are compared to three similar dyes based on the 6-methoxyquinoline nucleus, reported earlier by the authors, and also to dyes reported by Krapf et al. (Anal. Biochem. 169, 142-150, 1988). The interference of aqueous anions and the potential for using these dyes in biological halide-sensing applications are discussed.
Geddes
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The Photophysics Group, Department of Physics and Applied Physics, University of Strathclyde, John Anderson Building, 107 Rottenrow, Glasgow G4 ONG, United Kingdom.
Apperson
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Karolin
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Birch
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D002712:Chlorides / Q000032:analysis*; D005456:Fluorescent Dyes / Q000032:analysis* / Q000138:chemical synthesis; D007202:Indicators and Reagents; D011806:Quinolinium Compounds / Q000032:analysis* / Q000138:chemical synthesis; D012995:Solubility; D013050:Spectrometry, Fluorescence; D013053:Spectrophotometry; D013329:Structure-Activity Relationship
D002712:Chlorides; D005456:Fluorescent Dyes; D007202:Indicators and Reagents; D011806:Quinolinium Compounds