Factors influencing the haematoporphyrin-sensitized photoinactivation of Candida albicans.

Photosensitizing activity of haematoporphyrin (Hp) on Candida albicans cells is mainly promoted by unbound dye molecules in the bulk aqueous medium. Moreover, the death of photosensitized cells is dependent on the dye concentration, irradiation time, irradiation temperature, and the composition of the growth media. Morphological and biochemical studies indicate that the photoprocess involves an initial limited alteration of the cytoplasmic membrane, which allows the penetration of the dye into the cell with consequent photodamage of intracellular targets. In this respect, the Hp-sensitized photoinactivation of eukaryotic microbial cells differs from that in prokaryotic cells.