Commentary to "Biophotonics of molecules and nanoparticles": a session of the Russian Photobiology Society 9th Congress Shepsi, Krasnodar region, Russia; September 12-19, 2021.

Commentaries on the section "Biophotonics of molecules and nanoparticles" of the 9th Congress of the Russian Photobiological Society are presented. Presentations are briefly introduced along with the main conclusions made by their authors. This section included a plenary lecture, oral presentations, and posters with interesting talks and follow-up discussions.