Phosphonium Containing UV-Curable Antimicrobials for the Coating and Fabrication of Common Touch Plastics

The attachment and proliferation of antibiotic resistant, biofilm-forming bacteria to oft- handled material surfaces has emerged as a growing concern, particularly in the biomedical,  healthcare and food packaging industries. The development of both biocide-releasing and tethered, immobilized biocide surface coatings has risen to meet this demand. While these surface coatings have demonstrated excellent antimicrobial efficacy, there are few examples of antimicrobial surfaces with long-term durability and efficacy. To that end, UV-curable phosphoniums bearing benzophenone anchors were synthesized with a variety of alkyl, aryl, and fluoroalkyl functional groups at phosphorus to probe their efficacy as thermally stable antimicrobial additives in plastics or as surface coatings. The surface topology and characteristics of these materials were studied to gain insight into the mechanism of antimicrobial activity of these materials. Additionally, general design principals for tailoring phosphoniums to function as both additives during injection molding processes and as UV-curable coatings are described, and evaluation against both Gram-negative and Gram-positive bacteria in both applications were carried out. Crucially, polypropylene (PP) materials containing phosphonium with a perfluoroalkyl substituent maintained the ability to kill biofilm-forming bacteria even after being subject to abrasion processes, demonstrating the potential to serve as a long-term antimicrobial material.