Osteoblast Sensitivity to Topographical and Chemical Features of Titanium

Abstract

The titanium-osteoblast-interaction can be influenced both by surface roughness and by chemical modifications. We have ascertained that a positively charged titanium surface boosts osteoblast cells adhesion due to their negatively charged cellular hyaluronan coat. In current experiments, chemical surface modifications were combined with different topographies. Titanium disks of technical purity were modified (i) in their roughness by polishing (P), machining (M) and corundum blasting (CB), and (ii) by subsequently chemical functionalization by a thin film (d≤0.1 µm) of microwave plasma polymerized allylamine (PPAAm). In addition, collagen I was immobilized on PPAAm via the bifunctional linker polyethylene glycol diacid or glutar dialdehyde, respectively. The cell shape and material's contact of human osteoblasts was analyzed by FE-SEM and time dependent cell adhesion measured by flow cytometry. The cell dynamic of the adhesion component vinculin was observed in living cells. Amino-functionalization (PPAAm) considerably enhances the adhesion of osteoblasts in combination with topographical features, which was in contrast to collagen modified surfaces. PPAAm allows the cells to literally melt into the groove structure of the titanium. The bone cells lie over a large area and very close to the surface, so that the edges of the cells can hardly be distinguished from the structure of the surface. The combinatory effect of topography and plasma modification could improve bonding of the implant to the bone tissue.