Antibacterial oil-based polyurethane films for wound dressing applications

As an alternative to petroleum-based polyol, hydroxyl containing material was prepared from linseed oil for polyurethane synthesis. Hexamethylene di-isocyanate (HMDI) and/or 4, 4′-methylene diphenyl di-isocyanate (MDI) were used as isocyanate source. The polymerization reaction was carried out without catalyst. Polymer films were prepared by casting-evaporation technique. The MDI/HMDI-based polyurethane and its films had higher T_g and better thermal property than that of the HMDI-based one because of the existence of benzene ring in the polymer chain. Static water contact angle was determined to be 74°and 77.5° for HMDI and MDI/HMDI-based films, respectively. Water adsorption was found to be around 2.6-3.6% for both films. In vitro degradation of polyurethanes in phosphate buffered saline at 37°C was investigated by gravimetric method. Fourier transform infrared spectroscopy and scanning electron microscopy were used for confirmation of degradation on the polymer surface. The degradation rate of the HMDI-based polyurethane film was found higher than that of the MDI/HMDI-based film. Both the direct contact method and the MMT test were applied for determination of cytotoxicity of polymer films, and the polyurethane films investigated here was not cytotoxic. Silver-containing films were prepared using Biocera A® as filler and were screened for their antibacterial performance against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and/or Bacillus subtilis. The films prepared with and without Biocera A® exhibited antibacterial activity.