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

Abstract

As titanium (Ti) continues to be utilized in great extent for the fabrication of artificial implants, it is important to understand the crucial bacterium–Ti interaction occurring during the initial phases of biofilm formation. By employing a single-cell force spectroscopy technique, the nanoadhesive interactions between the early-colonizing Streptococcus sanguinis and a clinically analogous smooth Ti substrate were explored. Mean adhesion forces between S. sanguinis and Ti were found to be 0.32±0.00, 1.07±0.06, and 4.85±0.56 nN for 0, 1, and 60 seconds contact times, respectively; while adhesion work values were reported at 19.28±2.38, 104.60±7.02, and 1,317.26±197.69 aJ for 0, 1, and 60 seconds, respectively. At 60 seconds surface delays, minor-rupture events were modeled with the worm-like chain model yielding an average contour length of 668±12 nm. The mean force for S. sanguinis minor-detachment events was 1.84±0.64 nN, and Poisson analysis decoupled this value into a short-range force component of −1.60±0.34 nN and a long-range force component of −0.55±0.47 nN. Furthermore, a solution of 2 mg/mL chlorhexidine was found to increase adhesion between the bacterial probe and substrate. Overall, single-cell force spectroscopy of living S. sanguinis cells proved to be a reliable way to characterize early-bacterial adhesion onto machined Ti implant surfaces at the nanoscale.

Keywords:

• atomic force microscopy
• biophysics
• bacterial adhesion
• dental implants
• titanium

Acknowledgments

The authors would kindly like to thank the BecasChile PhD Scholarship Programme for funding this research.

Author contributions

SA contributed with data acquisition and analysis, and drafted the manuscript; ND contributed to the study conception, design, data analysis and interpretation, and critically revised the manuscript; DS contributed to conception, design, and critically revised the manuscript; and LB contributed to conception, design, data analysis and interpretation, and critically revised the manuscript.

Disclosure

The authors report no conflicts of interest in this work.