The effect of hypoxia on photocytotoxicity of TICS tricarbocyanine dye in vitro

To evaluate the effect of cell oxygenation on photocytotoxicity of a novel tricarbocyanine indolenine dye covalently bound to glucose (TICS). HeLa cells were incubated with 5 microM TICS, 2 h later irradiated by laser at 740 nm with a light dose of 10 J/cm(2), delivered at a power density of 10, 20, 25 or 30 mW/cm(2), in air or in argon atmosphere, and then scored for viability. The photocytotoxicity of TICS increased dramatically as the power density was reduced. Under hypoxia TICS-photosensitized cell death was determined but its value was lowered, compared to photoirradiation in the air. Photosensitizing effect of TICS is only partially dependent on the oxygenation of tumor cells.