Water-soluble pyrazole-pyridinium phthalocyanines for photodynamic inactivation of phage Phi6 as SARS-CoV-2 model

The severe acute respiratory syndrome coronavirus (SARS-CoV-2) is the leading cause of the COVID19 pandemic and is transmitted by virus laden respiratory, water droplets or contaminated surfaces. However, its presence in water bodies might be responsible for virus persistence and propagation to the human population. A significant amount of the wastewater released into the environment is not properly treated to efficiently eliminate microorganisms as e.g., viruses [1]. Photodynamic inactivation (PDI) of microorganisms has already shown to be effective against bacteria, fungi, and viruses [2-4]. During this treatment process, the short-lived excited state of the PS is converted into a long-lived triplet state that allows obtaining the reactive oxygen species (ROS), such as 1O2, which lead to severe oxidation of the vital cellular constituents of the microbial targets [4]. This study evaluated the use of quaternized zinc(II) phthalocyanines (ZnPcs) 2a and 3a for the PDI hypothesis to be considered a suitable approach for the inactivation of Phage φ6 as a surrogate for SARS-CoV-2 in wastewater treatment [5]. Thus, two new octa-substituted ZnPcs (2a and 3a, Fig. 1), bearing pyrazole-pyridinium groups, were synthetized and characterized. The PDI assays were performed with the quaternized ZnPcs 2a and 3a at low concentrations under white light irradiation with two irradiance intensities (50 and 150 mW.cm-2 ). For the PDI assays, the Phage φ6 was used as a surrogate for SARS-CoV-2.