Characteristics and biological responses of selective laser melted Ti6Al4V modified by micro-arc oxidation

Background/purpose: Additive manufacturing (AM) technology, such as selective laser melting (SLM), has been used to fabricate medical devices of Ti-6wt.% Al-4wt.%V (Ti6Al4V) alloys in dentistry. Strontium (Sr) has been shown to have the potential to treat osteoporosis. The aim of this study was to investigate the physicochemical and biological properties of strontium-containing coatings on selective laser melted Ti6Al4V (SLM-Ti6Al4V) substrate. Materials and methods: The disk of Ti6Al4V was prepared by SLM method. The strontium-containing coatings were prepared by micro-arc oxidation (MAO) in aqueous electrolytes. The surface topography, chemical composition, and phase of strontium-containing MAO (SrMAO) coatings were performed by scanning electron microscope (SEM), energy dispersive X-ray spectrometer (EDS), and thin film X-ray diffraction (TF-XRD), respectively. The apatite-forming ability of the MAO coatings was conducted in simulating body fluid (SBF), and the cell proliferation was determined by methylthiazoletetrazolium (MTT) assay. Results: The microstructure of SLM-Ti6Al4V displays acicular α-phase organization. The TF-XRD results indicated that the phase of SrMAO coating was anatase, rutile, and titanium. The calcium, phosphorus, and strontium were detected in the coatings by EDS. Using the SEM, the surface morphology of SrMAO coatings exhibited a uniform 3D porous structure. The SrMAO coatings could induce a bone-like apatite layer after immersion in SBF, and presented significantly higher cell proliferation than untreated specimens in in-vitro experiments. Conclusion: All findings in this study indicate that SrMAO coatings formed on SLM-Ti6Al4V surfaces exhibit a benefit on biological responses and thereby are suitable for biomedical applications.