title: Development of Singlet Oxygen Luminescence Kinetics during the Photodynamic Inactivation of Green Algae.
abstract: Recent studies show the feasibility of photodynamic inactivation of green algae as a vital step towards an effective photodynamic suppression of biofilms by using functionalized surfaces. The investigation of the intrinsic mechanisms of photodynamic inactivation in green algae represents the next step in order to determine optimization parameters. The observation of singlet oxygen luminescence kinetics proved to be a very effective approach towards understanding mechanisms on a cellular level. In this study, the first two-dimensional measurement of singlet oxygen kinetics in phototrophic microorganisms on surfaces during photodynamic inactivation is presented. We established a system of reproducible algae samples on surfaces, incubated with two different cationic, antimicrobial potent photosensitizers. Fluorescence microscopy images indicate that one photosensitizer localizes inside the green algae while the other accumulates along the outer algae cell wall. A newly developed setup allows for the measurement of singlet oxygen luminescence on the green algae sample surfaces over several days. The kinetics of the singlet oxygen luminescence of both photosensitizers show different developments and a distinct change over time, corresponding with the differences in their localization as well as their photosensitization potential. While the complexity of the signal reveals a challenge for the future, this study incontrovertibly marks a crucial, inevitable step in the investigation of photodynamic inactivation of biofilms: it shows the feasibility of using the singlet oxygen luminescence kinetics to investigate photodynamic effects on surfaces and thus opens a field for numerous investigations.
authors.affiliation: Department of Physics, Humboldt-Universität zu Berlin, Berlin 10099, Germany. Tobias.Bornhuetter@physik.hu-berlin.de.
authors.forename: Tobias
authors.initials: T
authors.lastname: Bornhütter
authors.affiliation: Department of Physics, Humboldt-Universität zu Berlin, Berlin 10099, Germany. Judith.Pohl@physik.hu-berlin.de.
authors.forename: Judith
authors.initials: J
authors.lastname: Pohl
authors.affiliation: Department of Physics, Humboldt-Universität zu Berlin, Berlin 10099, Germany. chrisf87@live.de.
authors.forename: Christian
authors.initials: C
authors.lastname: Fischer
authors.affiliation: Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa 32000, Israel. saltsman@tx.technion.ac.il.
authors.forename: Irena
authors.initials: I
authors.lastname: Saltsman
authors.affiliation: Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa 32000, Israel. chatif@tx.technion.ac.il.
authors.forename: Atif
authors.initials: A
authors.lastname: Mahammed
authors.affiliation: Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa 32000, Israel. chr10zg@tx.technion.ac.il.
authors.forename: Zeev
authors.initials: Z
authors.lastname: Gross
authors.affiliation: Department of Physics, Humboldt-Universität zu Berlin, Berlin 10099, Germany. Beate.Roeder@physik.hu-berlin.de.
authors.forename: Beate
authors.initials: B
authors.lastname: Röder
mesh_terms: D018441:Biofilms / Q000254:growth & development* / Q000528:radiation effects; D000460:Chlorophyta / Q000254:growth & development* / Q000528:radiation effects; D007700:Kinetics; D008027:Light; D049449:Luminescence; D008856:Microscopy, Fluorescence; D017319:Photosensitizing Agents / Q000737:chemistry*; D026082:Singlet Oxygen / Q000737:chemistry*; D013499:Surface Properties / Q000528:radiation effects
chemical_list: D017319:Photosensitizing Agents; D026082:Singlet Oxygen
keywords: biofilms; corroles; photodynamic inactivation; phototoxicity; singlet oxygen