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Journal of Biomedical Optics • Open Access

Ion-induced stacking of photosensitizer molecules can remarkably affect the luminescence detection of singlet oxygen in Candida albicans cells
Author(s): Ariane Felgenträger; Fernanda P. Gonzales; Tim Maisch; Wolfgang Baeumler

Paper Abstract

Singlet oxygen (1O2 ) is an important reactive intermediate in photodynamic reactions, particularly in antimicrobial PDT (aPDT). The detection of 1O2 luminescence is frequently used to elucidate the role of 1O2 in various environments, particularly in microorganisms and human cells. When incubating the fungus, Candida albicans, with porphyrins XF73 (5,15-bis-[4-(3-Trimethylammonio-propyloxy)-phenyl]-porphyrin) or TMPyP (5,10,15,20-Tetrakis(1-methyl-4-pyridinio)-porphyrin tetra(p-toluenesulfonate)), the 1O[sub]2 luminescence signals were excellent for TMPyP. In case of XF73, the signals showed strange rise and decay times. Thus,1O2 generation of XF73 was investigated and compared with TMPyP. Absorption spectroscopy of XF73 showed a change in absorption cross section when there was a change in the concentration from 1×10 −6   M to 1×10 −3   M indicating an aggregation process. The addition of phosphate buffered saline (PBS) substantially changed 1O2 luminescence in XF73 solution. Detailed experiments provided evidence that the PBS constituents NaCl and KCl caused the change of 1O2 luminescence. The results also indicate that Cl ions may cause aggregation of XF73 molecules, which in turn enhances self-quenching of 1O2 via photosensitizer molecules. These results show that some ions, e.g., those present in cells in vitro or added by PBS, can considerably affect the detection and the interpretation of time-resolved luminescence signals of 1O2 , particularly in in vitro and in vivo. These effects should be considered for any other photosensitizer used in photodynamic processes.

Paper Details

Date Published: 3 April 2013
PDF: 9 pages
J. Biomed. Opt. 18(4) 045002 doi: 10.1117/1.JBO.18.4.045002
Published in: Journal of Biomedical Optics Volume 18, Issue 4
Show Author Affiliations
Ariane Felgenträger, Univ. Hospital Regensburg (Germany)
Fernanda P. Gonzales, Univ. Hospital Regensburg (Germany)
Tim Maisch, Univ. Hospital Regensburg (Germany)
Wolfgang Baeumler, Univ. Hospital Regensburg (Germany)


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