Fabrication and cellular interactions of nanoporous tantalum oxide

Tantalum possesses remarkable chemical and mechanical properties, and thus it is considered to be one of the next generation implant materials. However, the biological properties of tantalum remain to be improved for its use in tissue engineering applications. To enhance its cellular interactions, implants made of tantalum could be modified to obtain nanofeatured surfaces via the electrochemical anodization process. In this study, anodization parameters were adjusted to obtain a nanoporous surface morphology on tantalum surfaces and systematically altered to control the pore sizes from 25 to 65 nm using an aqueous HF:H₂ SO₄ electrolyte. Results indicated the formation of Ta₂ O₅ -based nanoporous surface layers, which had up to 28% more surface area and increased nanophase roughness (more than twofolds) compared to nonporous tantalum upon the anodization. It was observed that the nanoporous tantalum oxide surfaces promoted nearly 25% more fibroblast proliferation at 5 days in vitro and 15.5% more cellular spreading. Thus, nanoporous tantalum oxide surfaces can be used to increase biological interactions of the cells and provide a means of improving bioactivity of tantalum for biomaterial applications.