N-trimethylchitosan/Alginate Layer-by-Layer Self Assembly Coatings Act as "Fungal Repellents" to Prevent Biofilm Formation on Healthcare Materials

Fungal biofilm formation on healthcare materials is a significant clinical concern, often leading to medical-device-related infections, which are difficult to treat. A novel fungal repellent strategy is developed to control fungal biofilm formation. Methylacrylic acid (MAA) is grated onto poly methyl methacrylate (PMMA)-based biomaterials via plasma-initiated grafting polymerization. A cationic polymer, trimethylchitosan (TMC), is synthesized by reacting chitosan with methyl iodide. Sodium alginate (SA) is used as an anionic polymer. TMC/SA multilayers are coated onto the MAA-grafted PMMA via layer-by-layer self-assembly. The TMC/SA multilayer coatings significantly reduce fungal initial adhesion, and effectively prevent fungal biofilm formation. It is concluded that the anti-adhesive property of the surface is due to its hydrophilicity, and that the biofilm-inhibiting action is attributed to the antifungal activity of TMC as well as the chelating function of TMC and SA, which may have acted as fungal repellents. Phosphate buffered saline (PBS)-immersion tests show that the biofilm-modulating effect of the multilayer coatings is stable for more than 4 weeks. Furthermore, the presence of TMC/SA multilayer coatings improves the biocompatibility of the original PMMA, offering a simple, yet effective, strategy for controlling fungal biofilm formation. Trimethylchitosan (TMC)/sodium alginate (SA) multilayers are coated onto poly methyl methacrylate (PMMA)-based materials. While Candida cells readily form biofilms on the original PMMA surface, they remain in the broth when incubated with PMMA surfaces containing TMC/SA multilayer coatings. Thus, the TMC/SA coatings act as fungal repellents that prevent Candida biofilm formation on healthcare materials.