Photodynamic therapy exploits the combined action of three elements, a sensitizing agent (the drug), light and oxygen to treat various kinds of tumors and diseases or to eradicate microbial pathogens. The photosensitizer agent is first administrated and becomes active only when irradiated with light. The activated drug transfers energy to molecular oxygen to generate reactive oxygen species (ROS), in particular singlet oxygen, that causes cell death. Our R&D result verified that pentaphyrins are efficient photosensitizers for the antimicrobial application of photodynamic inactivation (PDI). Pentaphyrins are a class of conjugated macrocycles in which five pyrrole units are connected together.
The pentaphyrinic compounds synthetized by the team has been shown to have significant antimicrobial activity, especially on bacteria, as a result of photo-oxidation of synthetic (bacterial monocultures) and real matrices (wastewater).
This new generation of photosensitizers demonstrated to be able, at nanomolar concentrations, to reach 4 log of photoinactivation of S. Aureus after 15 minutes of irradiation, 6 log after 30 min of treatment. The treatment is effective at low concentrations of photosensitizer and short treatment time. The intensity of the radiation required to activate the disinfectant process is extremely low, allowing to reduce environmental effects such as heating, and the light source wavelength of activation falls in a spectral range that prevents the administration of harmful UV radiation.