title: A spectroscopic study of the fluorescence quenching interactions between biomedically important salts and the fluorescent probe merocyanine 540.
abstract: The effects of several biologically important inorganic salts, including NaCl, NaI, NaBr, KCl, MgCl2, MgSO4 and CaCl2 on the electronic absorption and fluorescence spectra of Merocyanine 540 (MC-540) have been investigated in aqueous media at 25 degrees C. Depending on both the MC-540 concentration and the nature of salt, a new absorption band appears at about 515 nm, above the critical salt concentration (CSC), corresponding to salt-induced MC-540 aggregation. Several types of MC-540 fluorescence quenching by the salts are observed, according to their cationic charge and the nature of anion: in the case of monovalent ions (Na+, K+), a non-linear Stern-Volmer behaviour is observed, indicating variable contributions of dynamic and static quenching mechanisms, whereas for divalent alkaline-earth (Mg2+, Ca2+) ions, linear Stern-Volmer relationships are obtained. Using these results, an analytical quenchofluorimetric approach is proposed for the determination of magnesium ions.
authors.affiliation: Institut de Topologie et de Dynamique des Systèmes, Associé au CNRS, UPRESA 7086, Université Paris 7 Denis Diderot, France.
authors.forename: A
authors.initials: A
authors.lastname: Adenier
authors.forename: J J
authors.initials: JJ
authors.lastname: Aaron
mesh_terms: D000838:Anions; D002118:Calcium / Q000737:chemistry; D004305:Dose-Response Relationship, Drug; D006863:Hydrogen-Ion Concentration; D008274:Magnesium / Q000737:chemistry; D008278:Magnesium Sulfate / Q000737:chemistry; D008956:Models, Chemical; D011188:Potassium / Q000737:chemistry; D011744:Pyrimidinones / Q000737:chemistry*; D012492:Salts / Q000737:chemistry* / Q000494:pharmacology; D012964:Sodium / Q000737:chemistry; D012965:Sodium Chloride / Q000737:chemistry; D013050:Spectrometry, Fluorescence / Q000379:methods*; D013696:Temperature
chemical_list: D000838:Anions; D011744:Pyrimidinones; D012492:Salts; D012965:Sodium Chloride; C003954:merocyanine dye; D008278:Magnesium Sulfate; D012964:Sodium; D008274:Magnesium; D011188:Potassium; D002118:Calcium