The "Race for the Surface" experimentally studied: In vitro assessment of Staphylococcus spp. adhesion and preosteoblastic cells integration to doped Ti-6Al-4V alloys.

OBJECTIVE: Implant-related infection is a devastating complication in orthopedic surgery. Aiming to minimize this problem, many material modifications have been developed. Here we report a study of a surface modification of Ti-6 Al-4 V alloy using a methodology that enables the study of interactions between bacteria and the material in the presence of eukaryotic cells. METHODS: We mixed different concentrations of collection or clinical strains of staphylococci isolated from implant-related infections with preosteoblastic cells using a previously published methodology, analyzing the minimal concentration of bacteria able to colonize the surface of the material through image analysis. Ti-6 Al-4 V alloy was modified by anodization to obtain two F-doped nanostructured surfaces that have been previously described to have antibacterial properties. RESULTS: Our results show similar bacterial adhesion results to nanoporous and nanotubular F-doped surfaces. The presence of preosteoblastic cells increases the adherence of all bacterial strains to both structures. No effect of the surface on eukaryotic cells adherence was detected. CONCLUSION: To our knowledge, this is the first time that anin vitro study emulating the race for the surface evaluates and compares the osseointegration and antibacterial properties between two nanostructured- modified titanium alloy surfaces. Clinical strains show different behavior from collection ones in bacterial adherence. The presence of cells increased bacterial adherence. NP and NT surface modifications didn´t show significant differences in bacterial adhesion and preosteoblastic cells integration.

In vitro assessment of Staphylococcus epidermidis and Staphylococcus aureus adhesion on TiO2 nanotubes on Ti-6Al-4V alloy.

The aim of this study was to evaluate Staphylococcus sp. adhesion to modified surfaces of titanium alloy (Ti-6Al-4V). Specimens of Ti-6Al-4V alloy 6-4 ELI-grade 23 that meets the requirements of ASTM F136 2002A (AMS 2631B class A1) were anodized in a mixture of sulfuric/hydrofluoric acid at 20 V for 5 and 60 min to form nanoporous (NP) and nanotubular (NT) oxide layers with pore diameter of 20 and 100 nm, respectively. The amount of fluorine incorporated in the oxide films from the electrolyte was 6 and 4 wt %, respectively. Bacterial adherence was studied using laboratory strains and six clinical strains each of Staphylococcus aureus and Staphylococcus epidermidis. Lower adherence of laboratory strains was demonstrated on fluoride nanostructured surfaces in comparison with the fluoride-free surfaces. Significant differences between clinical strains and laboratory strains were also found (p < 0.0001, Kruskal-Wallis test) when NP and NT specimens were compared with chemically polished (CP) surfaces. The results of the tests using multiple clinical strains confirmed a decrease in bacterial adherence on F-containing titanium oxide surfaces, suggesting a potential applicability of this surface, with a confirmed added value of decreasing clinical staphylococci adherence, for medical prosthetic devices.