In vitro evaluation of the virucide activity of nanostructured antimicrobial coatings for personal protective equipments

INTRODUCTION One of the most effective personal equipments in preventing infection by respiratory viruses is wearing surgical masks for mouth and nose protection. The aim of this study is to evaluate in vitro whether different nanostructured coatings applied to surgical masks have a virucide activity. MATERIALS AND METHODS The tested coatings contained the following chemical principles: zeine solution (a vegetal protein) in ethanol/H2O and in ethanol/lactic acid, aqueous solutions of CuCl2 and NaOH (precursor to obtain nanometric cupper oxide), aqueous solution of Zn(NO₃)₂ and NaOH (precursor to obtain nanometric zinc), all at the same concentration (25 g/L). The coatings were obtained by soaking small coupons of TNT fabric in each solution for 30’ followed by air drying. For cupper and zinc based coatings, the samples were soaked in a NaOH solution and oxidated at 60°C for 24h. The virucide activity was studied against HCov-OC43, as a SARS-CoV-2 surrogate, Herpes Simplex Virus type-1, Human Adenovirus type 5 and Monkeypox Virus. The coupons coated with the different solutions were contaminated with the viruses under study and after 2’ the fabric samples were soaked in 1ml of cell growth medium and vortexed for 1’ to eluate the survived virus. Viral loads of these suspensions were titrated by end point dilution on cell cultures. RESULTS Preliminary experiments on surgical masks demonstrate a remarkable virucide activity of some coatings, though with different extent depending on the virus tested: the most effective ones appear to be zeine with lactic acid and the two cupper compounds (reduction > 2 Log). CONCLUSIONS Some of these coatings applied to polypropylene surfaces were already tested and demonstrated a considerable virus inhibition (in some cases up to 3 Logs). Therefore, this strategy for virus transmission containment seems to be promising, providing some advantages in comparison with traditional systems, such as lower toxicity and/or ecocompatibility.