Photophysical properties of porphyrin photosensitizers

The photodynamic properties of a new photosensitizer—dimegin (disodium salt of 2,4-di(1- methoxyethyl)-deuteroporphyrin-IX)—are studied in comparison with the properties of photosensitizers used in medical practice, namely, Photoditazine (dimethylglucamine salt of chlorin e6) and Radachlorin (trisodium salt of chlorin e6). The spectral characteristics, singlet oxygen generation ability, luminescence efficiency, and photostability of these photosensitizers are studied upon irradiation by light-emitting diode arrays in different spectral ranges. The ability of photosensitizers to generate singlet oxygen was estimated with the use of tryptophan as a chemical trap. The photostability was estimated by a change in the optical density of solutions in the Soret band after irradiation. It is shown that the photodynamic properties are related to the specific features of the optical absorption spectrum of the material. The results of this work testify to the possibility of using the Dimegin photosensitizer as an efficient drug for photodynamic therapy and fluorescent diagnostics. Comparative studies of luminescence, singlet oxygen generation, and photostability have shown that Dimegin surpasses Photoditazine and Radachlorin in many characteristics. In the future, these studies will help to choose the most efficient irradiation sources for photodynamic therapy and fluorescent diagnostic.