Effective bactericidal nanopillars for E. coli and S. aureus

Abstract

Due to competition of host and bacterial cells to adhere and grow on implant surfaces, implants are frequently associated with a high risk of peri-implant infections. The microorganisms that are abundantly present during peri-implant infections are Staphylococcus bacteria and a variety of other less abundant bacteria as for example Escherichia coli. For this reason, some studies have been focusing on creating nanopatterns that might reduce bacterial colonization when used as implant surface topography. However, most of this research showed that the specified nanopatterns were only exceedingly bactericidal to either Gram-positive or Gram-negative bacteria. The aim of this novel study is to investigate the bactericidal effects of nanopatterns with pillar diameter of ~ 80 nm, a height of ~ 190 nm and an interpillar distance of ~ 170 nm on Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli. The patterns were incubated with S. aureus and E. coli for 18 hours at 37 °C in their specific growth medium. The bactericidal effects were examined with scanning electron microscopy (SEM) by assessing the bacterial cell morphology and the amount of damaged bacterial cells found on the patterns. The patterns were able to damage approximately 96.9 ± 1.2% of E. coli and 83.9 ± 22.8% of S. aureus cells. The severity of bacterial cell damage has led to believe that the percentage of dead bacterial cells was a sufficient measure for the bactericidal efficacy of the pattern. Based on these results there is a convincing assumption that these specific pillar parameters can be used as a bactericidal surface topography on bone implants. Nevertheless, follow up experiments should be done in combination with live imaging of the cells to establish possible long-term bacterial- and host cell effects on topography and gain more insights into the proposed bactericidal mechanism(s).