Development of polyurethane antimicrobial coatings by composition with phenolic-, ionic- and copper-based agents

Microorganisms can be found in almost all environments with high-touch surfaces being an important fomite for microbial growth. Considering the health issues associated to acquired infection from inanimate surfaces, as well as the raising hygienic concerns, the incorporation of antimicrobial compounds in high-touch surfaces emerges as an effective solution for biomedical and common daily applications.

In this work, we incorporated different antimicrobial agents (phenolic-, ionic- and copper-based compounds) into polyurethane commercial formulations to produce anti- microbial lacquer-films and evaluated not only their physical/chemical properties, but also their antimicrobial activity against bacteria (Staphylococcus aureus, Escherichia coli), fungi (Candida albicans), and virus (SARS-CoV-2).

The incorporation of antimicrobial agents did not affect the performance of lacquer- films and the main properties were maintained, specifically the visual aspect, gloss values, optical properties and chemical stability.

Among the different compounds tested, copper-based lacquer-films exhibited the strongest antibacterial and antifungal activity, with a >4 log reduction, but not against virus. Importantly, copper-based lacquer-films maintained their cytocompatibility, even at high concentrations. Regarding the ionic lacquer-films, the highest tested concentration also showed a strong antimicrobial action (5 log reduction) against fungi and gram-positive bacteria, but not against gram-negative bacteria and virus. However, at this concentration, the ionic-containing lacquer-films presented cytotoxic potential. The phenolic-based compounds were not associated with antimicrobial activity, regardless the concentra- tions tested.

Collectively, these results highlight the potential of incorporating antimicrobial agents in polyurethane surface coatings as a promising strategy to avoid the microbial colonization on inanimate surfaces and, ultimately, prevent the spreading of potentially harmful pathogens among humans.