Fig. 1.

Screening of two photosensitizers by SARS-CoV-2 pseudoviruses entry assay. (A) Dose-responses of the inhibition of viral infectivity were also measured for photosensitizer ZnPc5K and ce6, giving the EC₅₀ and EC₉₀. The photosensitizers completely inhibited the viral infectivity at 1 μM concentration upon LED illumination. The EGFP intensities of all fields in a microplate well at different concentrations were summed to represent the virus infected into the cells. Error bars represent the SD of duplicates in one experiment. Scale bar, 500 μm. (B) Photocytotoxicity of ZnPc5k and ce6 on hACE2-293T cells was measured by CCK-8 assay and showed almost no phototoxicity up to 5 μM with a light dose of 0.48 J/cm². (C) Photosensitizers inactivated the SARS-CoV-2 pseudoviruses and reduced virus load inside ACE2-293T cells upon LED illumination. Serially diluted ZnPc5K or ce6 and pseudoviruses were incubated with ACE2-293T cells for 4 h, and illuminated by LED to a light dose of 0.48 J/cm². After further 44 h incubation, the fluorescent images (green for EGFP for virus and blue for Hoechst for nucleus staining) were recorded and analyzed. Error bars represent the SD of triplicates in one experiment. Scale bar, 500 μm.