Reduced Bacterial Growth on Titanium Screws With Nanophase TiO2 Surface Treatment

Abstract

Category: Other Introduction/Purpose: An important strategy in the reduction of orthopedic infections is to develop implant materials that prevent initial bacteria adhesion and growth onto implant surfaces. Bacterial localization and biofilm formation may lead to acute and chronic infections[1]. Biofilm formation on implant surfaces protects bacteria from the immune system and antibiotic therapy, thus, requiring an aggressive treatment of antibiotics that frequently do not work post biofilm formation[2]. Thus, to prevent implant infections, various strategies have been developed aside from conventional systemic and local antibiotic treatment. Recently, there has been increasing interest for coating implants with other materials to improve osseointegration and prevent infection, chronic inflammation, and unwanted foreign body responses[3]. The current study focuses on modifying the surface of titanium implants by treating them with nanophase titanium dioxide using electrophoretic deposition. Methods: Nanophase titanium dioxide was synthesized using a wet chemical synthesis and was deposited on Ti-6Al-4 V titanium screws using a cathodic arc deposition plasma system. Bacterial assays were conducted using Staphylococcus aureus (ATCC® 29740™), Pseudomonas aeruginosa (ATCC® 39324™) and an ampicillin resistant strain of E. coli (BIO-RAD Strain HB101 K-12 #166-0408 and pGLO Plasmid #166-0405). 0.03% tryptic soy broth (TSB) (Sigma Aldrich, Cat # 22092) and agar (Sigma-Aldrich, Cat # A1296) were used as the media and colony forming assays were performed to determine bacterial adhesion. Results: Nanophase titanium dioxide was successfully synthesized and applied onto the desired surface. A statistically significant decrease in bacterial adhesion was observed across all 3 strains of bacteria; an example of confocal images for S. Aureus is given in figure 1. In addition, decreased macrophage functions and increase osteoblast functions were also observed in the nano TiO2 treated Ti6Al4 V screws. Importantly, this was all achieved without the use of drugs and/or antibiotics decreasing the chance for the spread of antibiotic resistant bacteria and drug side effects. Conclusion: The screws were successfully coated using EPD and reduced bacterial adhesion on the coated surface was observed.