title: Photodegradation in Micellar Aqueous Solutions of Erythrosin Esters Derivatives.
abstract: Strong light absorption and high levels of singlet oxygen production indicate erythrosin B as a viable candidate as a photosensitizer in photodynamic therapy or photodynamic inactivation of microorganisms. Under light irradiation, erythrosin B undergoes a photobleaching process that can decrease the production of singlet oxygen. In this paper, we use thermal lens spectroscopy to investigate photobleaching in micellar solutions of erythrosin ester derivatives: methyl, butyl, and decyl esters in low concentrations of non-ionic micellar aqueous solutions. Using a previously developed thermal lens model, it was possible to determine the photobleaching rate and fluorescence quantum efficiency for dye-micelle solutions. The results suggest that photobleaching is related to the intensity of the dye-micelle interaction and demonstrate that the thermal lens technique can be used as a sensitive tool for quantitative measurement of photochemical properties in very diluted solutions.
authors.affiliation: Universidade Tecnológica Federal do Paraná, Santa Helena, PR 85892-000, Brazil.
authors.forename: Leandro Silva
authors.initials: LS
authors.lastname: Herculano
authors.forename: Gustavo Vinicius Bassi
authors.initials: GV
authors.lastname: Lukasievicz
authors.forename: Elizandra
authors.initials: E
authors.lastname: Sehn
authors.forename: Wilker
authors.initials: W
authors.lastname: Caetano
authors.forename: Diogo Silva
authors.initials: DS
authors.lastname: Pellosi
authors.forename: Noboru
authors.initials: N
authors.lastname: Hioka
authors.forename: Nelson Guilherme Castelli
authors.initials: NG
authors.lastname: Astrath
authors.forename: Luis Carlos
authors.initials: LC
authors.lastname: Malacarne
mesh_terms: D004923:Erythrosine / Q000737:chemistry*; D004952:Esters / Q000737:chemistry; D005456:Fluorescent Dyes / Q000737:chemistry*; D008823:Micelles; D038761:Photobleaching; D010782:Photolysis; D017319:Photosensitizing Agents / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D004952:Esters; D005456:Fluorescent Dyes; D008823:Micelles; D017319:Photosensitizing Agents; D014867:Water; D004923:Erythrosine