Measurement and comparison of the lifetime of Hematoporphyrin dihydrochloride <Hp. 2HCl>, Hematoporphyrin Derivative <HpD> and Pheophorbide a in PBS solution and TE-2 cultured esophagus cancer cells were performed using a N2 pulsed gas laser oscillating at 337.1nm in the ultraviolet region. The fluorescence decays of these three dyes in PBS solution were found to be approximated by the superposition of two exponential curves with different amplitudes and lifetimes. In the cases of Hp. 2HCl and HpD in TE-2 cancer cells, however, only one component was dominated and its lifetime was derived to become longer than that in the PBS solution. On the other hand, we obtained two components with different lifetimes from obserbed decay curves for Pheophorbide a uptaken in TE-2 cancer cells. It is conjectured that these different characteristics arise from the differece of accumulated portion of these dyes in the cancer cells.
