Abstract
A fluorescence micro-spectroscopic technique was applied to investigate intracellular photobleaching of mTHPC (Foscan) from micron-scale locations within individual formalin-fixed keratinocytes. The experimental results show that Foscan is highly photolabile in a cellular environment and the photobleaching phenomenon can be analysed via the modification of the fluorescence emission at 410 nm laser light. The progressive depletion of the 652 nm mTHPC fluorescence peak can be explained using bi-exponential decay kinetics which is consistent with singlet oxygen mediated process. The photobleaching plot against light dose shows an inverse-dose-rate dependence.