Tuning the response of osteoblast-like cells to the porous-alumina-assisted mixed-oxide nano-mound arrays.

Nanostructuring of biomaterials is used to create an appropriate interfacial layer that promotes stable cellular adhesion, proliferation, and differentiation on orthopedic and dental implants. Here, we synthesize self-organized arrays of composite-oxide nano-mounds through anodizing Al/Ta bilayers sputtered on substrates to cover the "missing" smallest size range of 10-40 nm for structuring an advanced inorganic biomaterial-Al2 O3 -doped Ta2 O5 films. The osteoblast-like cells appear to be able to recognize the finest differences in the film nano-morphologies. In the absence of serum proteins, the adhesion and cell growth are substantially enhanced on the 20 and 40 nm nanoarrays while in complete medium the cells show better initial adhesion on the 10 nm nanoarrays. The proliferation assay reveals a significant rise in cell number on the 20 and 40 nm nanoarrays during the first 7 days. A remarkable increase in the alkaline phosphatase activity is noticed on the 40 nm nanoarray. Immunostaining of cells adhered to the nano-mound surfaces shows that the cells are well spread over all the nanostructured films with organized actin fibers. The larger surface areas and improved focal contacts are again associated with the 20 and 40 nm nanoarrays. The findings help improve compatibility of living cells with the metal-oxide nanostructured surfaces developed for tissue engineering.