Modulation of biological properties by grain refinement and surface modification on titanium surfaces for implant-related infections

The nanostructured titanium (Ti) obtained by the equal-channel angular pressing (ECAP) has shown great promise as a biomedical implant material over the past few decades. The present work aims to investigate the effect of topographical changes caused by ECAP and piranha treatment (Tr) on the surface performance and biological properties of Ti for bone tissue engineering applications. The effects of dual treatments, i.e., ECAP and Tr, on Ti were systematically investigated by multiple characterization techniques, surface wettability, apatite-forming ability, cellular behavior, and antibacterial studies. We demonstrate that both ECAP and ECApTr samples possess desirable mechanical and physical properties and are biocompatible to cultured human fetal osteoblast (hFOB) cells. The potential of adhesion and proliferation of hFOB cells on ECAP and ECApTr samples was found to be superior to that of control unprocessed sample (annealed). Ti samples prepared by both methods showed excellent antimicrobial properties against clinical strains of the most common pathogenic bacteria causing orthopedic implant infections, Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa). This study supports the established claim about mechanical properties improvement by ultrafine refinement and further enhances the antibacterial properties when chemically etched with a piranha solution.