An atomic force microscopy investigation of the interfacial properties of biocompatible nanostructured titanium oxide films

Cluster-assembled nanostructured Titanium Oxide (ns-TiOx) deposited by Supersonic Cluster Beam Deposition (SCBD) [1] recently proved to be a very promising biomaterial, allowing the adhesion and proliferation of cancer and primary cells, with no need of additional coating with extra-cellular matrix proteins [2], and the adhesion of proteins, such as streptavidin, with no need of additional coatings of polycations [3]. Little is known of the specific role played by surface properties of ns-TiOx in the interaction of proteins with nanostructured biocompatible materials. Here we present an atomic force microscopy (AFM) study of the morphological and adhesive properties of ns-TiOx biocompatible surfaces. AFM provides nanometer spatial resolution in both imaging and force spectroscopy modes and it is therefore the technique of choice for the investigation of biologically relevant surface properties of nanomaterials. AFM in force-volume (FV) mode has been used to characterized the local adhesive properties, in an effort to establish a correlation between the meso- and macroscopic wetting and adhesive behavior of ns-TiOx films and local morphological and chemical properties, which in turn are expected to play a major role in the adhesion and interaction of proteins with surfaces.. To this purpose we have developed a patterning strategy based on the combined use of SCBD and Nanosphere Lithography [9], for the production of sub-micrometre patterns of ns-TiOx on glass or other substrates. This allowed the concurrent investigation of the local adhesive properties of the nanostructured and another reference material, and put the basis at the same time for the development of platform allowing the multi-technique investigation of biointerfaces.