Microbial adhesion to natural and synthetic materials surfaces is a challenging problem e.g. in food industry, sewage treatment and most importantly in the biomedical field. Recently, nanostructured materials gained interest because of their effect on microbial adhesion. An advanced understanding of the microbe-material-interaction is required for the current development and progress in nanoscale structuring of materials surfaces to control microbial adhesion. This study aimed to investigate the nanostructure of the microbe-material-interface and to link it to microbial adhesion kinetics as a function of the titanium surface nanoroughness, to gain new insight into controlling microbial adhesion via materials’ surface nanoroughness.
Titanium surfaces with different nanoroughnesses were prepared by physical vapor deposition and the time-dependent adhesion of Escherichia coli and Staphylococcus aureus was analyzed. A statistically significantly reduced microbial adhesion (p ≤ 0.05) by 55.6 % (E. coli) and 40.5 % (S. aureus) on the titanium surfaces with a nanoroughness of 6 nm and the lowest surface peak density compared to 2 nm roughness accompanied by the highest surface peak density was observed. Direct insight into the titanium-microbe-interface was gained by cross-sectioning of the microbial cells with a focused ion beam and high resolution scanning electron microscopy (SEM) imaging. SEM micrographs gave first evidence that the surface peaks are the loci of initial contact between the microbial cells and the material’s surface. In a qualitative model we propose that the initial microbial adhesion on nanorough surfaces is controlled by the titanium surface peak density via nano adhesion points. This new understanding will help towards the design of materials surfaces for controlling microbial adhesion.