Is there an optimal topographical surface in nanoscale affecting protein adsorption and cell behaviors?

With the development of nanotechnology, nano-structured surfaces exhibit superior biological activities to the smooth or micro-structured surfaces. To study whether or not there is an optimal topographical surface in nano-scale affecting protein adsorption and cell behaviors, aluminum oxide membranes with different topographical structures in nano-scale were prepared by anodic oxidation technique. The surface morphology, topography, and wettability were analyzed by atomic force microscopy and water contact angle measurement, respectively. These membranes surfaces were dominated by hill-shaped grains with different diameters ranging from 20 to 120 nm. With the increase of diameters, the average surface roughness and mean square roughness of membranes surfaces varied from 1.1 +/- A 0.1 to 12.6 +/- A 0.9 nm and from 4.4 +/- A 0.3 to 16.5 +/- A 1.2 nm, respectively. A dynamic albumin adsorption analysis indicated that the membrane containing grains with 40 nm in diameter had a weaker ability of protein adsorption at the early stage; but the final amount of adsorbed protein had no significant differences compared with other membranes. Additionally, the morphological, metabolic and cell counting methods showed no significant effects of the aluminum oxide membranes on the viability and proliferation of rat mesenchymal stem cells.