Surface nanostructuring of titanium imparts multifunctional properties for orthopedic and cardiovascular applications

Highlights: • Nanocrystalline titanium surface was produced by surface severe plastic deformation. • Stem cell response and fatigue resistance in simulated body environment concurrently improved after surface nanostructuring. • Nanocrystalline titanium also exhibited superior hemocompatibility. • Protein adsorption regulated biological responses via changes in physico-electro-chemical properties of the surface oxide. Commercially pure titanium (cp-Ti) is a metallic biomaterial used in orthopedic and cardiovascular applications. Here, surface nanocrystalline cp-Ti produced by surface mechanical attrition treatment (SMAT) is shown to exhibit multifunctional properties for orthopedic and cardiovascular applications. Nanocrystallization simultaneously enhanced the stem cell response and fatigue resistance in simulated body fluid of cp-Ti collectively required for load bearing orthopedic applications. Stem cell attachment and proliferation was enhanced by 20% and number of cycles to failure increased by 15% after nanocrystallization. Nanocrystalline Ti was also found to be suitable for cardiovascular applications due to its improved hemocompatibility. A 40% reduction in attachment of platelets and their activation was noted on the surface of nanocrystalline Ti. While high surface hardness and compressive residual stress improved the corrosion-fatigue resistance, the biological response of stem cells and platelets was governed by the physico-electro-chemical properties of the surface oxide on cp-Ti. Modulation in properties of the oxide layer altered the protein adsorption, evaluated by means of electrochemical impedance spectroscopy and direct protein quantification thereby, augmenting the biological response. Taken together, it is demonstrated that surface nanocrystallization by SMAT is a promising step towards producing high performance Ti implants for orthopedic and cardiovascular applications.