title: Photophysics of the interaction between a fluorescein derivative and Ficoll.
abstract: Ficoll has been widely used as a crowding agent to mimic intracellular media because it is believed to be noninteracting and is composed of mixed sizes such that smaller and larger diffusing solutes can be studied. Due to the interest that the fluorescent dye 9-[1-(2-methyl-4-methoxyphenyl)]-6-hydroxy-3H-xanthen-3-one (TG-II) as a fluorometric probe of phosphate ions in intracellular media could generate, we describe the spectral characteristics of the system TG-II-Ficoll in aqueous solution by means of absorption spectroscopy, steady-state fluorescence, time-resolved fluorescence, time-resolved emission spectroscopy, and fluorescence lifetime correlation spectroscopy. The spectral characteristics found are consistent with the formation of an adsorption complex on the surface of Ficoll, probably due to hydrogen bonding between TG-II and Ficoll. In addition, the diffusion coefficient calculated for the association was similar to the diffusion coefficient previously recovered for Ficoll in the same experimental conditions. Therefore, our overall data clearly demonstrate that Ficoll is not an inert crowding agent when in the presence of fluorescein derivative dyes.
authors.affiliation: Department of Physical Chemistry, University of Granada, Granada, Spain.
authors.forename: Jose M
authors.initials: JM
authors.lastname: Paredes
authors.forename: Luis
authors.initials: L
authors.lastname: Crovetto
authors.forename: Angel
authors.initials: A
authors.lastname: Orte
authors.forename: Sergio G
authors.initials: SG
authors.lastname: Lopez
authors.forename: Eva M
authors.initials: EM
authors.lastname: Talavera
authors.forename: Jose M
authors.initials: JM
authors.lastname: Alvarez-Pez
mesh_terms: D005362:Ficoll / Q000737:chemistry*; D019793:Fluorescein / Q000737:chemistry*; D005453:Fluorescence; D005456:Fluorescent Dyes / Q000737:chemistry; D015394:Molecular Structure; D055668:Photochemical Processes
chemical_list: D005456:Fluorescent Dyes; D005362:Ficoll; D019793:Fluorescein