Biomaterials-associated infections are most frequently caused by the colonization of microorganisms on the materials’ surface. In the form of biofilms, bacterial cells are higly resistant against biocides and mechanical stress. Previously, it was shown that titanium surfaces with a nano-roughness in the range of 2 – 6 nm have the potential to reduce microbial adhesion. The nano-roughness of our previous approach is limited due to the instrumental restriction of physical vapor deposition (PVD). We aim to extend this research by examining the previously uninvestigated roughness range of Ra= 2 – 16 nm. Additionally, we wish to understand how the nano-roughness influences microbial adhesion, and therefore will be modifying the previous approach. Hence, we use a wet alkaline etching approach to overcome this technical bottleneck combined with the preparation of a second layer by PVD to produce nano-rough titanium thin films in the range of Ra= 2 – 16 nm.
Titanium thin films, as prepared by PVD with a nano-roughness of about 3 nm, were consequently treated in NaOH solution with tunable concentration, in order to achieve surfaces with an extended nano-roughness range from 6 to 24 nm. Through a second titanium layer prepared by the PVD, uniform chemical properties of the different rough surfaces shall be ensured. Atomic force microscopy (AFM), scanning electron microscopy (SEM) as well as x-ray photoelectron spectroscopy (XPS) were used to characterize the surfaces in terms of roughness, morphology and chemical properties.
We present our first results of nano-rough titanium thin films produced with this method. It is possible to create roughness through etching in the predefined range. The SEM images show different morphologies not only before and after etching, but also before and after the second preparation by the PVD. Similarly, the chemical properties differ before and after the etching process as well as after the second round of PVD.
These results show that this method is suitable to produce nano-rough titanium surfaces in the required range. This is the foundation for investigating the influence of nano-rough surfaces on microbial adhesion.
We thank the DFG for funding of our project: “Antimicrobial Effect of Nano-rough Titanium surfaces: Reduction of Microbial Adhesion and Mechanisms of Reduction” AOBJ: 622946