Nanoadhesion ofStaphylococcus aureusonto Titanium Implant Surfaces

Abstract

Adhesion of bacteria to dental implant surfaces is the critical initial step in the process of biofilm colonization; however, the specific nanoadhesive interactions occurring during the first contact between bacterial cells and biomaterial substrates remain poorly understood. In this report, we utilize single-cell force spectroscopy to characterize the dynamics of the initial interaction between living Staphylococcus aureus cells and machined titanium surfaces at the nanoscale. Values for maximum adhesion force were found to increase from 0-s (-0.27 ± 0.30 nN) to 60-s (-9.15 ± 0.78 nN) surface delays, with similar results observed for total adhesion work (7.39 ± 2.38 and 988.06 ± 117.08 aJ, respectively). Single unbinding events observed at higher surface delays were modeled according to the wormlike chain model, obtaining molecular contour-length predictions of 314.06 ± 9.27 nm. Average single-bond rupture forces of -0.95 ± 0.04 nN were observed at increased contact times. Short- and long-range force components of bacterial adhesion were obtained by Poisson analysis of single unbinding event peaks, yielding values of -0.75 ± 0.04 and -0.58 ± 0.15 nN, respectively. Addition of 2-mg/mL chlorhexidine to the buffer solution resulted in the inhibition of specific adhesive events but an increased overall adhesion force and work. These results suggest that initial attachment of S. aureus to smooth titanium is mostly mediated by short-range attractive forces observed at higher surface delays.

Influence of biomaterial nanotopography on the adhesive and elastic properties of Staphylococcus aureus cells

“…For SCFS experiments, customised colloidal probes were fabricated in order to immobilise S. aureus cells by utilising a protocol previously published 23 . Briefly, the end of a tipless cantilever (NP-O10, Bruker, Santa Barbara, USA) was brought into contact with a thin layer of UV-curable glue (Loctite, UK) for 10s.…”

“…Several studies have used AFM to probe the nanomechanics of S. aureus and its adhesion to substrates and other cells [22][23][24] . However, little is known regarding the influence that nanopatterning exerts on S. aureus adhesion and early-colonisation of the implant surface.…”

Probing the nanoadhesion of Streptococcus sanguinis to titanium implant surfaces by atomic force microscopy

“…27 Briefly, ~10 μm diameter glass microspheres (Whitehouse Scientific, Chester, UK) were attached to NP-O10 tip-less cantilevers (Bruker) by employing a thin layer of ultraviolet (UV)-curable glue (Loctite, Hemel Hempstead, UK). Optical microscopy and scanning electron microscope (SEM) confirmed adequate attachment of a single microsphere on each cantilever.…”

“…This value is higher than the contour length reported for Staphylococcus aureus (314.06±9.27 nm) using a similar protocol. 27 Not many reports are available in the literature regarding SCFS experiments with S. sanguinis. There are, however, some studies regarding nanoadhesion of other streptococcal strains that may allow for some discussion.…”

“…It was found Interestingly, F SR values were higher than the ones observed for S. aureus when using the same substrate. 27 Considering that bacterial attachment to hydrophilic surfaces has been suggested to be predominantly mediated by hydrogen bonding, with an individual bond force of approximately -0.13 nN, 37 it is possible to hypothesize that a minimum of 12 hydrogen bonds are formed between the S. sanguinis cell probe and the surface during AFM probing. This increased bond formation capacity in S. sanguinis could help to explain the increased early-colonizing behavior of this strain toward hard surfaces in the oral cavity.…”