Intracellular relocalization of anionic photosensitizers measured by cw and time-gated microscopy and spectroscopy

摘要

Intracellular modifications of anionic photosensitizers during PDT were observed, dependent on the growth phase of the incubated cells. In addition to steady-state spectroscopy, time- resolved fluorescence spectra between different time gates were measured. Comparative results were obtained for the sensitizers meso-tetra(4-sulfonatophenyl)porphyrine (TPPS$-4$/) and aluminumsulfophthalocyanine (AlS$-2$MIN@3$/Pc). In both cases relocalization of the sensitizer could be observed exclusively for cells in the growing phase, whereas no relocalization was detected for cells in the stationary phase. Moreover, time-gated spectra were different for the two cell types. The formation of a fluorescent band around 615 nm during PDT for the sensitizer TPPS$-4$/ was observed mainly for cells in the growing phase. This species was correlated with a short fluorescence decay time ($LS 5 ns). Similar observations were done with AlS$-2$MIN@3$/Pc. A fluorescence band blue-shifted in the same order of magnitude (about 30 nm from the original band) and measured predominantly between an `early' time-gate (0-5 ns) was detected for cells in the growing phase.