Virucidal action in cotton fabrics and facial masks promoted by phenothiazines

Virucidal action in cotton fabrics and facial masks promoted by phenothiazines

• Autor
• Lilian dos Santos Martins
• Co-autores
• Adrianne M. M. Brito , Julia D. Bronzato , Martha T. Oliveira , Otaciro R. Nascimento , Silgia A. Costa , Sirlene M. Costa , Iseli Lourenço Nantes
• Resumo

• During the current pandemic, SARS-CoV-2 has constantly changed through mutation, thus creating new variants. Self-disinfecting materials, including face masks, are one important tool to interrupt virus transmission chains within the community. Photosensitizers have been studied as self-disinfecting materials because they can generate biocidal reactive oxygen species (ROS) under light exposure. Phenothiazines are photosensitizers and, in the aggregated state form stable long-lived cation radicals by type I mechanism. In the present study, phenothiazine nucleus (PTZ) was impregnated in cotton fabrics and face masks to provide virucidal properties by the oxidative action of its cation radical. The samples were inoculated with the enveloped virus Human coronavirus-229E (HCoV-229E) to investigate the capacity of PTZ free radicals to promote pro-oxidant destruction of the viral envelope. A significant decrease of genome copies of HCoV-229E was detected by qRT-PCR from cells inoculated with viral particles removed from cotton fabric treated with Fluphenazine (FP), Phenothiazine (PHT) and Sulphur Black (SB), but not from untreated cotton fabric. In the other words, FP and PHT were able to inactivate the enveloped virus HCoV-229E. The industrial dye SB exhibited the same photochemical properties and is also a promising virucidal agent. Face masks with PHT as well showed virucidal properties. To the best of our knowledge, this is the first demonstration of the free radical generation in cotton fabrics and face masks for the prevention of viral infection, especially by the industrial sulfur black dye. The samples were characterized by UV-visible spectrometry, FTIR, FT-Raman, EPR, and colorimetry. The UV-visible spectrum of the original cotton fabric does not exhibit a significant contribution in the UV and visible spectral range. In UV-visible spectra, cotton fabrics treated with PTZ exhibited spectral contributions in the UV region, due to the presence of the aromatic rings, and in the visible region due to the persistence of the cation radicals peaking at 510 nm (FP), 530 nm (PHT) and 650 nm (SB). The FTIR spectra of treated fabrics were dominated by the vibrational contributions of the cotton molecules. However, the signals at 1248 cm-1 (C-F), 1595 cm-1 (N-H) and 1648 cm?1 (RR’C=NR”) were present only in the fabrics treated with FP, PHT and SB, respectively. EPR measurements were performed to confirm the presence of free radicals and their resistance to washing. All fabrics treated with PTZ exhibited free radical spectra after twice cycles of washing with water under stirring followed by UV irradiation for 15 min. The simulation of the EPR spectrum that reveals the presence of associated nitrogen in the washed fabric corroborated this result, even as the Raman spectrum presents a peak in 1034cm-1 attributed the to C-S ring. The stability of PHT?+ in cotton fabrics was evidenced by direct detection of the EPR signal even after two months of storage in the dark. The PHT?+ exhibits pink color related to a broad visible spectral band with a peak at 520 nm. This color of PHT-modified cotton fabric was also analyzed by colorimetry which indicates a time-dependent increase in color strength. Facial mask samples with PHT also featured 530 nm band in the absorption spectrum, vibrational contributions at 1595 cm-1 (N-H) in FTIR, and cation radical sign in EPR. To determine the mechanism by which the PTZ promotes the inactivation of enveloped virus HCoV-222E, Transmission Electron Cryomicroscopy (CRYO-TEM) was used. HCoV-222E with 13mM aqueous PHT solution presented a three-fold reduction in intact viral particles when compared to the HCoV-229E sample only. The amount of envelope debris increased four-fold when compared to the HCoV-229E sample only and the vesicles with spike decreased seven-fold when compared to the HCoV-229E sample only. These results show that PTZ and its cation radicals to kill and inactivate the virus.

• Palavras-chave
• Virucidal action; cotton fabrics; facial masks; phenothiazines.
• Modalidade
• Comunicação oral
• Área Temática
• Materias Funcionais Avançados