Antibacterial and Biocompatible Cross-Linked Waterborne Polyurethanes Containing Gemini Quaternary Ammonium Salts

A cross-linked waterborne polyurethane (CPTMGPU) with long-term stability was developed from poly(ethylene glycol) (PEG), polyoxytetramethylene glycol (PTMG), isophorone diisocyanate (IPDI), l-lysine, and its derivative diamine consisting of gemini quaternary ammonium salt (GQAS), using ethylene glycol diglycidyl ether (EGDE) as a cross-linker. Weight loss test, X-ray photoelectron spectroscopy (XPS) measurements, and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) were performed to prove the surface structure and stability of these CPTMGPU films. Furthermore, the GQAS-bearing CPTMGPUs show repeatable contact-active antibacterial efficacy against both Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli) bacteria and do not show any inhibition effect against fibroblasts in vitro. After subcutaneous implantation in rats, the CPTMGPU films manifest good biocompatibility in vivo, despite the presence of a typical foreign body reaction toward surrounding tissues and mild systematic inflammation reaction that could be eliminated after a short implantation period, as demonstrated by histology and immunohistochemistry combined with interleukin (IL)-1β, IL-4, IL-6, IL-10, and TNF-α analysis though enzyme-linked immunosorbent assay (ELISA) and real-time quantitative polymerase chain reaction (qRT-PCR). Therefore, these cross-linked waterborne polyurethanes hold great promise for antibacterial applications in vivo.