Development of iodine based sustained release antimicrobial coatings for polyurethane voice prostheses

Voice prostheses are known to fail in few weeks to several months of implantation due to the clogging mainly caused by microbial biofilm formation, which is a cause of concern. Iodine is a known broad-spectrum biocide and is reported to easily form complexes with various polymers. For long term device disinfection, strong iodine complexation that offers sustained iodine release for a prolonged period is essential. The present research work deals with the synthesis of a poly(methyl methacrylate-n-butyl acrylate-N-vinyl-2-pyrrolidone) (poly[MMA-BA-NVP]) tercopolymer through free radical polymerization for surface coating thermoplastic polyurethane (TPU) based voice prostheses. The NVP content in the tercopolymer was varied from 20% to 50% to optimise iodine loading and subsequent release. Base TPU coated with the tercopolymer was treated with 4% aqueous iodine solution at room temperature (28 ± 3 °C) for two hours. It was observed that the tercopolymer containing 35% N-vinyl-2-pyrrolidone (NVP), 32.5% methyl methacrylate (MMA) and 32.5% butyl acrylate (nBA) gave a stable coating on TPUs together with sustained iodine release for a prolonged period. Furthermore, the tercopolymer coated and iodine loaded TPUs exhibited excellent antimicrobial activity against Candida albicans, Staphylococcus aureus and Escherichia coli.