Revisiting Tetra-p-Sulphonated Porphyrin as Antimicrobial Photodynamic Therapy Agent

Photodynamic inactivation is known as a new antimicrobial photodynamic therapy (aPDT). It is based on the administration of a photosensitizer located in the bacterial/viral cell followed by exposure to light radiations (with a proper wavelength corresponding with the maximum value of absorption of the photosensitizer) that generate singlet oxygen or reactive oxygen species, which lead to the death of different microorganisms. This review will present an overview beyond the state-of-the-art of the photosensitizer types (based on tetra-p-sulphonated-phenyl porphyrin—TSPP, which is able to form cationic and J-aggregates forms at different pH values ((1–4) and concentrations around 10−5 M) and their applications of PDT for viruses, especially. The mechanism of dicationic and J-aggregates formation is presented in this paper, and the photophysical parameters have been collected and harmonized to support their behaviours. Studies on Herpes Simplex virus type 1 (HSV-1) are useful, because without the help of HSV-1, the COVID-19 virus may not be able to cause serious illness or death in humans. This method could be a new direction for COVID treatment and immunization, either to prevent infections or to develop photoactive fabrics (e.g., masks, suits, gloves) to disinfect surfaces, under artificial light and/or natural sunlight. The use of photodynamic therapy (PDT) can be an alternative approach against SARS-CoV-2 that deserves to be explored.