Tuning cell adhesion on titanium with osteogenic rosette nanotubes

Self-assembled rosette nanotubes (RNTs), obtained from a twin G∧C base functionalized with lysine-arginine-serine-arginine [KRSR-(G∧C)(2)], were designed and investigated as bioactive coatings on titanium. These results were compared to RNTs derived from Lysine-G∧C (K-G∧C), Arg-Gly-Asp-G∧C (RGD-G∧C), and aminobutane-(G∧C)(2) [AB-(G∧C)(2)]. The results from this study revealed that these materials had excellent cytocompatibility properties as they enhanced osteoblast (bone forming cell) adhesion when coated on titanium. In particular, KRSR and RGD functionalized RNTs coated on titanium promoted the greatest osteoblast densities relative to untreated titanium. Furthermore, KRSR functionalized RNTs selectively improved osteoblast adhesion relative to fibroblast (soft-tissue forming cell) and endothelial (cells that line the vascular) cell adhesion. In contrast with these results, RNTs obtained from an unfunctionalized twin base [AB-(G∧C)(2)], RGD-G∧C co-assembled with K-G∧C and K-G∧C significantly enhanced endothelial cell attachment, which may find applications in the vascularization of newly formed bone tissue. In summary, these studies suggest that the surface of orthopedic implant materials (such as titanium) could be tailored to promote selective cell adhesion using biologically-inspired nanotubular structures functionalized with osteogenic compounds.