PhD Candidate Colorado State University Fort Collins, Colorado, United States
Introduction: Orthopedic implants are one of the most essential implants for the body as they affect the quality of life of patients. To achieve its desired function(s), it's vital for implants to successfully integrate with the body. For orthopedic implants, this process is called osseointegration. Titanium and its alloys have been long prized for their excellent mechanical and chemical properties, corrosion resistance and biocompatibility. However, a lot of these implants have two issues; they don’t integrate with the bone properly and are prone to infection. For poor integration, a lot of commercial implants have a rough surface coating which allows the bone to attach with them. These coatings are made of titanium oxide/ hydroxyapatite (mineral content of the bone). For the infection issue, not a lot has been done on the implant material itself, but patients after surgery are prescribed antibiotic drugs to prevent infection. It’s not always effective as bacteria can be resistant to the drugs. Thus, there is a need to develop implant surfaces which prevent infection whilst promoting new bone growth. A lot of work is being done in this area where researchers have modified the surface topography, and/or chemistry by fabricating nanostructures like nanotubes, nanoflowers, onto the micro rough surface leading to a micro-nano hierarchical structure which is like the natural architecture of bone which helps cells to integrate better with the surface. Recently, copper has become an attractive ion to dope on surfaces to create them anti-bacterial. Copper has also shown that it can promote osteo-conduction.
Materials and
Methods: The titanium surface was first modified to make TiO2 nanotubes (NT) via an anodization process. NT was then doped with copper using a Chemical Vapor Deposition. The surfaces were characterized using scanning electron microscopy (SEM), water contact angle measurements, and X-ray photoelectron spectroscopy (XPS). Staphylococcus Aureus and Pseudomonas Aeruginosa were seeded on the surfaces and their adhesion and proliferation was investigated after 6- and 24-hours using SEM and fluorescence microscopy. Human Adipose Derived Stem Cells (ADSCs) were cultured on the surfaces and their adhesion, proliferation and osteogenic differentiation was investigated after days 4, 7, 14 and 28 of seeding using SEM and fluorescence microscopy.
Results, Conclusions, and Discussions: SEM results show that all surfaces present uniform and vertically oriented nanotubes, and that the surface modification with copper does not change the nanotube topography. XPS indicates the successful modification of NT surfaces with copper and contact angles results show that nanotube surfaces are hydrophilic. Adhesion and proliferation studies show that NT surfaces modified with copper had significant lower number of bacteria after 24-hours in comparison with titanium. In addition, both surfaces doped with copper promoted enhanced antibacterial properties compared with undoped surfaces. NT surfaces modified with copper displayed cell adhesion, growth and differentiation, with the cell growth being equivalent to that on the Titanium by Day 28.
Conclusions: The results show that copper-doped NT decreased the bacteria adhesion and proliferation whilst allowing Human ADSCs to adhere, proliferate and differentiate to osteoblasts, which is crucial for the successful osseointegration.
