<p>Biological response of chemically treated surface of the ultrafine-grained Ti&ndash;6Al&ndash;7Nb alloy for biomedical applications</p>

Abstract

Background: Nanophase surface properties of titanium alloys must be obtained for a suitable biological performance, particularly to facilitate cell adhesion and bone tissue formation. Obtaining a bulk nanostructured material using severe plastic deformation is an ideal processing route to improve the mechanical performance of titanium alloys. By decreasing the grain size of a metallic material, a superior strength improvement can be obtained, while surface modification of a nanostructured surface can produce an attractive topography able to induce biological responses in osteoblastic cells. Methods: Aiming to achieve such an excellent synergetic performance, a processing route, which included equal channel angular pressing (ECAP), hot and cold extrusion, and heat treatments, was used to produce a nanometric and ultrafine-grained (UFG) microstructure in the Ti-6Al-7Nb alloy (around of 200 nm). Additionally, UFG samples were surface-modified with acid etching (UFG-A) to produce a uniform micron and submicron porosity on the surface. Subsequently, alkaline treatment (UFG-AA) produced a sponge-like nanotopographic substrate able to modulate cellular interactions. Results: After several kinds of biological tests for both treatment conditions (UFG-A and UFG-AA), the main results have shown that there was no cytotoxicity, expressed alkaline phosphatase activity and total protein amounts without statistical differences compared to control. However, the UFG-AA samples presented an attractive effect on the cell membranes, and cell adhesions were preferentially induced as compared with UFG-A. Both conditions demonstrated cell projections, but for UFG-AA, cells were more widely dispersed, and more quantities of filopodia formation could be observed. Conclusion: Herein, the reasons for such behaviors are discussed, and further results are presented in addition to those mentioned above.

Study on Corrosion Behavior of Ultrafine-Grained Ti-6Al-7Nb Fabricated by Equal Channel Angular Pressing

“…Oliveira et al [16] reported that Ti-6Al-7Nb alloy processed by ECAP with an average grain size~200 nm had higher fatigue properties, which make it suitable for practical application. At the same time, a highly bioactive behavior of UFG Ti-6Al-7Nb alloy after phosphoric acid etching, regardless of the usage of alkaline treatment, was reported by Oliveira et al [17].…”

“…Recently, ultrafine-grained (UFG) and nanocrystalline (NC) materials processed by severe plastic deformation (SPD) have been widely investigated and found to have unique physical and chemical properties [11][12][13]. Enhanced mechanical behavior and biocompatibility of UFG/NC Ti-6Al-7Nb alloy were acquired after the SPD process [14][15][16][17][18][19]. For instance, Polyakova et al [9] revealed that the tensile strength of the UFG Ti-6Al-7Nb alloy with grain size of 330 nm increased to 1210 MPa after equal channel angular pressing (ECAP), which was 20% higher than observed in coarse-grained (CG) counterparts.…”

TiAl6V4 Alloy Surface Modifications and Their Impact on Biofilm Development of S. aureus and S. epidermidis

“…Numerous physical and chemical surface modifications can and have been applied to metallic biomaterials in general [11], specifically to titanium-based materials [12], and most recently to the application of nano-modifications [13]. This has led to the invention of many new types of titanium-based orthopedic materials with not only a higher resistance to corrosion and better tribological properties [14,15], but also improved mechanical properties [16][17][18][19]. In addition, biocompatibility [19] and resistance to bacterial infections [12,[20][21][22] can be positively influenced by those newly developed materials.…”

Analysis of the mechanical and physicochemical properties of Ti‐6Al‐4 V discs obtained by selective laser melting and subtractive manufacturing method

“…However, there is no evidence that a very rough surface (Ra > 5 μm) promotes specific effects on osteoblast differentiation, 38 and there is no consensus on a maximum roughness value considered detrimental to cell biology during osseointegration or on the optimal roughness for osteoblast differentiation. 25,30 The rough surface of SLM samples was also observed in SEM images, with the presence of spherical particles that were not fused, partially fused, or weakly attached to each other. These findings can be due to the parameters used in the SLM technique such as material, particle size of the Ti powder, layer thickness, laser type and power, and scanning parameters.…”

“…A conventional heating plate was used to heat the acid medium to 80 C and then the samples were immersed in the solution for 30 min. Afterwards, the samples underwent an alkaline treatment by immersion into 75 ml of NaOH solution at 10 mol/L kept at 60 C for 24 h[29][30] (Table 1)(Figure 1).…”