[Photosensitizing properties of 3,3'-diethylthiacarbocyanine in biological media]

The objective of the study is elucidation of perspectives of 3,3'-diathylcarbocyaine application as a photosensitizer for curing viral infections by photodynamic therapy. Lipid-containing bacteriophage PM-2 of Pseudoalteromonas espejiana was used as a model. The testing was carried out at a special installation modeling photodynamic exposure conditions towards a non-fractionated phage lysate. 3,3'-DECC demonstrated a rapid photo-bleaching when added tothe phage lysate but not to water. The initial rate of PM-2 phage photoinactivation was proportional to the square concentration of the dye in the range of 0.5-9 μmol/L. This confirms a hypothesis that the dimer is the principal photochemically active form of the dye. An improved ability to form dimers was found in the dye in the phage lysate (10-folds better than in the water). The dye formed a stable adduct with the bacteriophage material. This adduct had an extinction maximum at λ(max) = 594 nm and demonstrated the properties of a polymer (sedimentation under a low-speed centrifugation).