Transparent Polymeric Formulations Effective against SARS-CoV-2 Infection

The main route of the transmission of the SARS-CoV-2 virus is through airborne small aerosol particles containing viable virus as well as through droplets transmitted between people within close proximity. Transmission via contaminated surfaces has also been recognized as an important route for the spread of SARS-CoV-2 coronavirus. Among a variety of antimicrobial agents currently in use, polymers represent a class of biocides that have become increasingly important as an alternative to existing biocidal approaches. Two transparent polymeric compounds, containing silver and benzalkonium ions electrostatically bound to a polystyrene sulfonate backbone, were synthesized, through simple procedures, and evaluated for their antimicrobial properties against Gram-positive and Gram-negative bacteria and Candida albicans (ISO EN 1276) and for their antiviral activity toward 229E and SARS-CoV-2 coronaviruses (ISO UNI EN 14476:2019). The results showed that the two tested formulations are able to inhibit the growth of (1.5-5.5) × 10¹¹ CFU of Gram-positive bacteria, Gram-negative bacteria, and of the fungal species Candida albicans. Both compounds were able to control the 229E and SARS-CoV-2 infection of a target cell in a time contact of 5 min, with a virucidal effect from 24 to 72 h postinfection, according to the European Medicines Agency (EMA) guidelines, where a product is considered virucidal upon achieving a reduction of 4 logarithms. This study observed a decrease of more than 5 logarithms, which implies that these formulations are likely ideal candidates for the realization of transparent surface coatings that are capable of maintaining remarkable antibacterial activity and SARS-CoV-2 antiviral properties over time.