Material related antibacterial surfaces: Nanosilver, cicada wing effects and sacrifical anode systems
Manfred Köller, BG University Hospital Bergmannsheil, Ruhr-Universität Bochum, Bochum, GermanyChristina Sengstock, Surgical Research, Department of Surgery, BG University Hospital Bergmannsheil, Ruhr-University, Bochum, GermanyPetri Bellova, Surgical Research, Department of Surgery, BG University Hospital Bergmannsheil, Ruhr-University, Bochum, GermanyYahya Motemani, Institute for Materials, Faculty of Mechanical Engineering, Ruhr-University , Bochum, GermanyChinmay Khare, Institute for Materials, Faculty of Mechanical Engineering, Ruhr-University , Bochum, GermanyAlfred Ludwig, Institute for Materials, Faculty of Mechanical Engineering, Ruhr-University , Bochum, GermanyMatthias Epple, Institute of Inorganic Chemistry, University of Duisburg-Essenn, Essen, Germany
Due to an increase in bacterial resistance towards antibiotics, the development of biomaterials with antibacterial properties which hinder or prevent bacterial colonization by a specific topography and composition is an important challenge in biomaterial research. Therefore, nanocolumnar Ti thin films were fabricated by glancing angle sputter deposition (GLAD) on silicon substrates and two types of bacteria (gram-positive S. aureus as well as gram-negative E. coli) were incubated with the nanostructured or with reference dense Ti thin film test samples.
It was shown that the viability of E. coli was significantly decreased on the nanostructured film compared to the dense film. This was accompanied by an irregular bacterial morphology and a cell wall deformation. This effect was completely induced by mechanical cell-surface interaction. A similar antibacterial effect was not found using S. aureus. However, a particular antibacterial effect towards both bacterial strains could be achieved by the use of metallic silver especially by nanoparticular silver, which led to higher silver ion release due to the enlarged surface.
In addition, an alternative method to enhance silver ion release was established. Here, sputtered Ag dot arrays on Au thin film (sacrifical anode system for Ag) exerted a significantly higher antibacterial effect on both types of bacteria compared to Ag dot arrays fabricated on the Ti thin films. This was due to the increased release of Ag ions from dissolution of Ag dots on Au-films. The combination of both material related antibacterial mechanisms (i.e. nanostructure and the sacrifical anode principle) shall lead to innovative antibacterial surfaces for future implants and medical devices.