Nano-structure-mediated Functionalization of Titanium： Effects of Nanonodular Structuring on Protein Adsorption and Cell Attachment Capacities

Abstract

Objectives: Currently available surface modification technologies for endosseous implants seem to have reached a plateau for enhancing the biological potential of implants for better osseointegration. Nano-structuring technology has proven to create unique biological properties in various biomaterials. We recently discovered a self-assembly of uniform nano-scale nodular structures that specifically occurs during physical and chemical depositions of metal or non-metal onto specifically-conditioned micro-textured surfaces of various materials. The formation of these nano-nodules can be controlled in size from under 100 nm to over 1,000 nm, and can even mimic biological molecules. The objective of this study was to examine the protein adsorption and osteoblast cell attachment capacities of titanium surfaces with this nano-nodular structure.
Materials and methods: Ti rods with three different surface topographies were prepared: machined, acid-etched and 200 nm nano-nodular surfaces. The nano-nodular surface was created by sputtering TiO₂ onto the acid-etched titanium surface. Protein adsorption capacity of titanium surfaces was examined by placing a Ti rod in the rat femur for 3 h. Cell attachment was evaluated by incubating rat bone marrow-derived osteoblastic cells round the Ti rod for 6 h.
Results: The quantity of cells attached to a titanium rod during incubation for 6 h was 2-fold greater for the nano-nodular surface than for the acid-etched surface. The difference between the nano-nodular and machined surfaces was 6～8 times. Protein adsorbed to the nanonodular surface during incubation for 3 h was 5 and 2 times increased compared to those for the machined and acid-etched surfaces, respectively.
Conclusion: The titanium surface with unique nano-nodular structure substantially enhanced the protein adsorption and cell attachment capacities of titanium over the acid-etched micro-textured surface, providing a groundbreaking route to novel and effective Ti functionalization. Future in vivo studies should be designed to test its osseointegration capability and to determine the usefulness of this nano-structuring technology for clinical application.