The photodynamic inactivation of Staphylococcus aureus in water using visible light with a new expanded porphyrin

In this work, the results of the application of organic expanded porphyrins in the disinfection of water by the photodynamic inactivation (PDI) technique are presented. The photoinactivation properties of a novel, expanded porphyrin, namely 20-(4-carboxyphenyl)-2,13-dimethyl-3,12-diethyl-(22π) pentaphyrin (PCCox), were tested in the disinfection of water using Staphylococcus aureus as a Gram-positive bacteria model. The data showed that PCCox was effective against S. aureus bacteria at nanomolar concentrations. The variation with irradiation time and concentration was studied using both a multi-LED monochromatic light (λ = 470 nm) and an incandescent light bulb with a wide emission spectrum. A PCCox dosage of 5 μM was sufficient to achieve a 99.997% abatement of S. aureus within 1 h of 40 W/m² irradiation with monochromatic light (λ = 470 nm), whereas under the same conditions using irradiation with white light, the abatement was 99.9997%.