12 January 1995 Photomodification of ALA-induced protoporphyrin IX in cells in vitro
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Proceedings Volume 2325, Photodynamic Therapy of Cancer II; (1995) https://doi.org/10.1117/12.199173
Event: International Symposium on Biomedical Optics Europe '94, 1994, Lille, France
Cells of the line WiDr were incubated with media containing different concentrations of (delta) -aminolevulinic acid (ALA) and the amount of the produced protoporphyrin (Pp) IX was evaluated by means of steady-state fluorescence. The photomodification process of ALA- induced Pp IX was investigated by measuring spectroscopic properties of cells suspensions incubated with 0.2 mM and 1 mM of ALA. Light exposure of cells containing Pp IX resulted in a decrease of fluorescence intensities at 635 and 705 nm ((lambda) exc equals 413 nm) due to photobleaching and in an increase of fluorescence intensity at around 670 nm due to the formation of a photoproduct. These spectral changes arise from photochemical reactions resulting in the formation of photoprotoporphyrin and destruction of porphyrin ring. The fluorescence kinetics indicate that for ALA-induced Pp IX in cells the ring opening reaction prevails the photoprotoporphyrin formation. Singlet oxygen may be involved in both processes since the photobleaching is slowed down on bubbling N2 through the samples and photoprotoporphyrin formation is slightly faster in suspensions in phosphate buffered saline (PBS) made of D2O compared with suspensions in PBS made of H2O.
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Giedre Streckyte, Giedre Streckyte, Kristian Berg, Kristian Berg, Johan Moan, Johan Moan, "Photomodification of ALA-induced protoporphyrin IX in cells in vitro", Proc. SPIE 2325, Photodynamic Therapy of Cancer II, (12 January 1995); doi: 10.1117/12.199173; https://doi.org/10.1117/12.199173

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