Spectral- and time-resolved phosphorescence of photosensitizers and singlet oxygen: From in vitro towards in vivo
Abstract
Spectral- and time-resolved infrared phosphorescence set-up was adapted for detection from surfaces of solid samples by utilizing fiber optics. Its abilities are demonstrated on the detection of singlet oxygen photosensitization by intrinsic (protoporphyrin IX synthesized from ALA) and extrinsic (TPPS4 and TMPyP) photosensitizers in in vitro layers of cultured 3T3 murine fibroblasts and HeLa cells mimicking in vivo tissues.
Complex decays of phosphorescence of the photosensitizers were detected. The data were approximated by multi-exponential decays, however, no straightforward explanation of the individual components was found.
Singlet oxygen phosphorescence kinetics were obtained with rise-times corresponding to singlet oxygen lifetimes ranging from 0.7 mu s to 1.0 mu s and single-exponential decay times between 5.3 mu s and 6.5 mu s for different photosensitizers and cell lines.