Interaction of bacterial cells with cluster-assembled nanostructured titania surfaces : an atomic force microscopy study

The nanoscale interaction of bacterial cells with solid surfaces is a key issue in biomedicine because it constitutes the first pathogenic event in the complex series of biofilm development on prosthetic devices. We report on an Atomic Force Microscopy study of the interaction of Escherichia coli and Pseudomonas aeruginosa bacterial cells with nanostructured titania thin films with controlled and reproducible nanometer-scale morphology, produced by assembling Ti clusters from the gas phase in a Supersonic Cluster Beam Deposition apparatus. The results demonstrate that bacterial adhesion and biofilm formation are significantly influenced by a pure physical stimulus, that is, the nanoscale variation of surface topography. The increase of nanoscale film roughness promotes bacterial adhesion with respect to flat substrates; remarkably, Pseudomonas aeruginosa cells lose their flagella on nanostructured TiO2 thin films upon adhesion, as opposed to same bacteria onto reference smooth glass substrates. Further, we have observed increased cell biovolume and other biofilm properties on nanostructured substrates in comparison with smooth glasses. These findings suggest that the design of innovative biomaterials with a suitable patterning of biomaterials surfaces can be an effective approach to control the adhesion of microorganisms to in vivo implant surfaces with active biological functionalities.