Antiviral and antibacterial activity of sodium alginate/poly(diallyldimethylammonium chloride) polyelectrolyte film for packaging applications

Pathogen agents, such as bacteria and virus, can contaminate plastic surfaces, particularly those used in food packaging. This study proposed to prepare a polyelectrolyte film with antiviral and antibacterial activity based on sodium alginate (SA) and poly(diallyldimethylammonium chloride) (PDADMAC), a cationic polymer with sanitizing properties. In addition, the physicochemical properties of the polyelectrolyte films were also evaluated. The polyelectrolyte films showed continuous, compact, and crack-free structures. The FTIR analysis confirmed the ionic interaction between SA and PDADMAC. Adding PDADMAC significantly affected the mechanical properties of the films (p < 0.05), increasing the maximum tensile strength (from 8.66 ± 1.55 MPa to 18.1 ± 1.77 MPa). However, polyelectrolyte films showed higher water vapor permeability values due to the strong hydrophilicity of PDADMAC, representing a 43 % average increase compared with the control film. Also, thermal stability improved with the incorporation of PDADMAC. The selected polyelectrolyte film inactivated 99.8 % of SARS-CoV-2 after 1 min in direct contact with the virus, in addition to having an inhibitory effect against Staphylococcus aureus and Escherichia coli bacteria. Therefore, this study demonstrated the efficacy of using PDADMAC in the preparation of polyelectrolyte sodium alginate-based films with improvements in physicochemical properties and especially with antiviral activity against SARS-CoV-2.