Figure 4.

Cytotoxicity of PS without illumination. The cytotoxic effect of the four tested PSs in the dark was determined for cells seeded into microplates that were preincubated with PS and for cells that were seeded into microplates before PS was added (standard protocol). Twenty-four hours thereafter, cellular survival was assessed by means of resazurin assay. Results are expressed as ratio relative to untreated control. Abbreviations: exp, experiment; PS, photosensitizer; (PVP-)Hyp, (polyvinylpyrrolidone-)Hypericin.