Post-Synthetic Functionalization of Porous Materials (MOFs and Silica) with Tetrapyrrole Macrocycles as Antiviral Materials against Coronaviruses and Hepatitis C Virus

Mesoporous silica SBA-15 and two Metal-Organic Frameworks (MOFs), UiO-66(Zr)-NH₂ and MIL-125(Ti)-NH₂, were functionalized with tetrapyrrole macrocycles (TpM), two chlorin, and two porphyrin molecules with a simple coupling reaction, creating a strong covalent amide bond. Next, their antiviral activity was assessed against HCoV-229E, two highly pathogenic coronaviruses, SARS-CoV-2 and MERS-CoV, and Hepatitis C virus (HCV). Infection tests in vitro took place under dark or visible light exposure for different contact times, and it was found that 15 min of exposure for pheophorbide A (PhA)-functionalized materials was enough to safely inactivate the viruses. A drop in the infectivity of HCoV-229E by more than 99.99% was achieved with all three PhA-functionalized materials, while for SARS-CoV-2, only SBA-15-NH-PhA and UiO-66(Zr)-NH-PhA showed a potent antiviral activity of >99.99%. Furthermore, these two materials were tested against MERS-CoV and HCV, having an effect of 99.88% and 92.31% for MERS-CoV and 91.84% and 90.63% for HCV, respectively. The effect of the photosensitizer on the functionalization of silica, as the best-performing material, was studied, and it was found that protoporphyrin IX (PPIX) and chlorin e6 (Ce6) had better antiviral activity than PhA and TCPP. The antiviral activity of these materials springs from the photosensitizer, which can produce singlet oxygen ¹O₂ (in the case of PhA) or hydroxyl radicals HO• (for PPIX and Ce6), two ROS species that oxidize the envelope of the viruses.