31 January 1996 Photophysics of photosensitizing dyes in living cell suspensions
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The use of photosensitizers to generate cytotoxic species in situ following exposure to light is finding a wide range of applications. The photophysics of these sensitizers have been well characterized in homogeneous solution and in some microheterogeneous phases, however there have only been limited studies of the photophysics of the sensitizers inside living cells. Such studies are crucial to the unambiguous elucidation of the photodynamic mechanism within the cell and to the development of improved sensitizers and treatment modalities. We have constructed a laser flash photolysis system designed specifically to probe the fate of the triplet state of excited sensitizer molecules in living cell suspensions. Steady state and time resolved fluorescence techniques have also been applied to characterize the photophysics of aluminum disulphonated phthalocyanine (AlPcS2) in aqueous suspensions of bacteria, yeast and murine cell lines. We have observed considerable aggregation of AlPcS2 in all cell lines. We report triplet lifetimes in the absence of oxygen which suggest that sensitizer triplet state deactivation is primarily oxygen dependent. Fluorescence lifetime measurements suggest that there is no quenching of the singlet state. We have also made progress towards the reduction of early time spikes which render singlet oxygen luminescence detection in aqueous solution difficult.
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Timothy C. Oldham, Timothy C. Oldham, Ilya V. Eigenbrot, Ilya V. Eigenbrot, Ben Crystall, Ben Crystall, David Phillips, David Phillips, } "Photophysics of photosensitizing dyes in living cell suspensions", Proc. SPIE 2625, Photochemotherapy: Photodynamic Therapy and Other Modalities, (31 January 1996); doi: 10.1117/12.231011; https://doi.org/10.1117/12.231011

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