Understanding the Role of Polymer Surface Nanoscale Topography on Inhibiting Bacteria Adhesion and Growth

Catheter-associated infections, most of which are caused by microbial biofilms, are still a serious issue in healthcare and are associated with significant morbidity, mortality, and excessive medical costs. Currently, the use of nanostructured materials, especially materials with nanofeatured topographies, which have more surface area, altered surface energy, enhanced select protein adsorption, and selectively increased desirable cell functions while simultaneously decreasing competitive cell functions, seem to be among the most promising ways for reducing initial bacteria attachment, biofilm formation, and infections. In this study, polydimethylsiloxane (PDMS), a commonly used polymeric catheter material, was formulated to mimic the nanopatterned topography of natural tissue by using a template method with nanotubular anodized titanium. Results showed that increased PDMS surface nanoscale roughness alone can inhibit both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria adhesion and growth for up to 2 days, the time length of the current study. Additionally, increased fibroblast and endothelial cell adhesion on nano-PDMS indicated that this nanoscale topography had no toxic effects toward mammalian cells. Mechanistically, this study also developed a model for the first time to correlate bacteria responses to nanoscale roughness with initial protein and biomolecule adsorption (specifically, casein protein and glucose, which are unique biomolecules that mediate bacteria functions). Data revealed that the increase in nanoscale roughness and associated energy contributed to greater select casein adsorption during the first several minutes of culture, which is critical for decreasing bacteria attachment and growth. In contrast, no significant differences for glucose adsorption between samples before and after nanofabrication were identified. These results together indicated that the present biomimetic nanopatterned PDMS surface without any chemical or antibiotic modification has the potential to combat catheter-associated infections and should be further investigated.