T.J. Tzeng, S.B. Behbahani, J.D. Desjardins
Clemson University,
United States
Keywords: orthopedic implant, biofilm, nanoparticle
Summary:
Bacterial biofilm formation on implant surfaces is a significant contributor to orthopedic implant infections. Self-regulating local infection and biofilm formation capabilities in orthopedic implants can be instrumental in preventing and treating implant-associated infections. In this study, dynamic compression plate implant surfaces underwent modifications employing two surface modification techniques, i.e., CoBlast™ and BioDep™. Polytetrafluoroethylene (PTFE) and biodegradable chitosan with local antibiotic (vancomycin) elution were deposited onto stainless steel and titanium implants to mitigate biofilm formation and bacterial infection. The CoBlast™ technique employed a stream of abrasive particles, including alumina with or without PTFE dopant, to permeate the surfaces of materials, such as metals, at a micron level. Conversely, the BioDep™ process involved a plasma deposition of chitosan and vancomycin biomolecules at ambient temperature, ensuring the local release of the antibiotic into the surrounding implant area. The efficacy of modified surfaces in preventing infection and biofilm formation was assessed. The S. aureus Seattle 1945 (ATCC 25923) strain, the most prevalent pathogen associated with orthopedic implant infections, was utilized to characterize biofilm on metallic coupons. The BioDep™-deposited coupons demonstrated successful prevention of bacterial attachment to the surface, irrespective of the base material. While the release rate and duration increased with more deposited layers, there were stability concerns associated with excessive deposition layers. Based on the in vitro analysis of surface-modified coupons, nine deposition layers were identified as the optimal BioDep™ treatment for implant materials in the in vivo study. The efficacy of the antibiotic coating on metallic implants was evaluated in a bacterial-challenged rabbit model over a 28-day period. All implants with the BioDep™ coating successfully prevented bacterial infection and biofilm formation, whereas the unmodified titanium implants did not exhibit such outcomes. This study suggests that depositing vancomycin and chitosan onto the surface of metallic implants may prove to be a beneficial approach for preventing short-term biofilm formation.