Surface patterning and modification of polyurethane biomaterials using silsesquioxane-gelatin additives for improved endothelial affinity

Polyurethanes (PUs) are well-known for their biocompatibility but their intrinsic inert property hampers cell-matrix interactions. Surface modifications are thus necessary to widen their use for biomedical applications. In this work, surface modifications of PU were achieved first by incorporating polyhedral oligomeric silsesquioxane (POSS), followed by alteration of the surface topography via the breath figures method. Subsequently, surface chemistry was also modified by immobilization of gelatin molecules through grafting, for the enhancement of the surface cytocompatibility. Scanning electron microscopy (SEM) was used to verify the formation of highly ordered microstructures while static contact angle, FTIR and XPS confirmed the successful grafting of gelatin molecules onto the surfaces. In vitro culture of human umbilical vein endothelial cells (HUVECs) revealed that endothelial cell adhesion and proliferation were significantly enhanced on the gelatin-modified surfaces, as shown by live/dead staining and WST-1 proliferation assay. The results indicated that the combination of the strategies yielded an interface that improves cell attachment and subsequent growth. This enhancement is important for the development of higher quality biomedical implants such as vascular grafts.