"Fundamental principles of photodynamic, laser and PUVA therapy": a session of the Russian Photobiology Society 9th Congress (Shepsi, Krasnodar region, Russia; September, 12-19, 2021).

At the section "Fundamentals of photodynamic, laser and PUVA therapy," 32 reports were presented in full-time and on-line format. Representatives of various scientific schools reported on the results of fundamental and applied research on the processes occurring at the cellular and organismal levels upon irradiation with low-intensity red light and upon the introduction of photosensitizers of various nature, followed by laser irradiation. Scientific reports proposed new photosensitizers, as well as their conjugates with biologically active molecules for fluorescent diagnostics and photodynamic therapy of oncological diseases. Plenary reports were presented by Professor Mikhail Grin "Natural chlorins as a promising platform for creating drugs with photoinduced antitumor and antimicrobial activity," Professor Alexander Krasnovsky "Laser activation of dissolved oxygen in natural conditions," and Professor Elena Filonenko "Photodynamic therapy in the treatment of demodicosis of the facial skin with topical application of a gel based on 5-ALA." At the poster section, young scientists presented 18 posters, which describe in detail the research voiced in the section reports.