Spectral properties of stilbazolium merocyanines - potential sensitizers in photodynamic therapy and diagnosis

The efficiency of triplet states generation of the dyes incorporated into stimulated cells has been evaluated using time-resolved photothermal spectroscopy. As follows from the photographs of stained cancerous cells taken by means fluorescence microscope, merocyanines are located predominantly in cell membranes. The spectral properties of the dye-sensitizes in solutions and in the cells can differ therefore the selection of proper sensitizers for medical applications made on the ground of the investigation of dye molecules in simple artificial model systems is only preliminary. The selected dyes have to be further investigated after introducing them into resting and PHA-stimulated lymphocytes. It has been shown that the dyes exhibiting high yields of triplet state generation in the stimulated cells usually are also efficient sensitizers of photodynamic reactions. The exceptions are the dyes undergoing fast photobleaching in the cells.