Revealing Commercial Epoxy Resins’ Antimicrobial Activity: A Combined Chemical–Physical, Mechanical, and Biological Study

In our continuing search for new polymer composites with antimicrobial activity, we observed that even unmodified epoxy resins exhibit significant activity. Considering their widespread use as starting materials for the realization of multifunctional nanocomposites with excellent chemical and mechanical properties, it was deemed relevant to uncover these unexpected properties that can lead to novel applications. In fact, in places where the contact with human activities makes working surfaces susceptible to microbial contamination, thus jeopardizing the sterility of the environment, their biological activity opens the way to their successful application in minimizing healthcare-associated infections. To this end, three commercial and widely used epoxy resins (DGEBA/Elan-TechW 152LR, 1; EPIKOTETM Resin MGS®/EPIKURETM RIM H 235, 2 and MC152/EW101, 3) have been investigated to determine their antibacterial and antiviral activity. After 24 h, according to ISO 22196:2011, resins 1 and 2 showed a high antibacterial efficacy (R value > 6.0 log reduction) against Staphylococcus aureus and Escherichia coli. Resin 2, prepared according to the ratio epoxy/hardener indicated by the supplier (sample 2a) and with 10% w/w hardener excess (sample 2b), exhibited an intriguing virucidal activity against Herpes Simplex Virus type-1 and Human Coronavirus type V-OC43 as a surrogate of SARS-CoV-2.