Peptide-Grafted Waterborne Polyurethane With Enhanced Biocompatibility and Mechanical Properties for Biomedical Applications

The incorporation of fillers into waterborne polyurethane (WPU) can endow the composites with improved physicochemical and physiological properties for biomedical applications. Silk fibroin possesses excellent mechanical properties and biocompatibility owing to its unique hierarchical structure comprising β-sheet crystallites and amorphous matrix. To mimic its structure, a crystalline tetrapeptide Gly-Ala-Gly-Ala (GAGA) derived from the repetitive segments of the primary sequence of fibroins was grafted onto the WPU backbone. The tetrapeptides aggregated via additional hydrogen bonds to form crystalline domains, which served as physical crosslinking points to significantly improve the mechanical properties of WPU. Compared with the pristine WPU, the modification enhanced the maximum tensile strength (from 13.1 to 25.4 MPa) and hydrophilicity (the water contact angle from 80.6° to 38.8°). In addition, the modified WPU with the optimal proportion of the tetrapeptide remained structurally stable under physiological environments and showed improved biocompatibility including good cell and protein adhesion, noncytotoxicity, and nonhemolysis. The excellent performance confirms the effectiveness of peptides in WPU modification and sheds light on the potential of modified WPU in biomedical applications.