Porous Ti Alloy Research Articles

Preparation of Ag@3D-TiO2 Scaffolds and Determination of its Antimicrobial Properties and Osteogenesis-promoting Ability.

The micro-nano structure of 3D-printed porous titanium (Ti) alloy with excellent performance in avoiding stress shielding and promoting bone tissue differentiation provides a new opportunity for the development of bone implants, but it necessitates higher requirements for bone tissue differentiation and the antibacterial properties of bone implants in clinical practice. This study investigated the preparation, antimicrobial properties, and osteogenesis-promoting ability of the 3D printed porous Ti alloy anodic oxidized Ag-carrying (Ag@3D-TiO2) scaffolds. The 3D printed porous Ti alloy (3D-Ti), anodized 3D printed porous Ti alloy (3D-TiO2), and Ag@3D-TiO2 scaffolds were synthesized using electron beam melting. The antimicrobial properties of the scaffolds were examined using antibacterial tests and their cytocompatibility was assessed using a cell proliferation assay and acridine orange/ethidium bromide (AO/EB) staining. In vitro cellular assays were used to investigate the effects of the scaffold microstructural features on cell activity, proliferation, and osteogenesis-related genes and proteins. In vivo animal experiments were used to evaluate the anti-inflammatory and osteogenesis-promoting abilities of the scaffolds. The Ag@3D-TiO2 scaffolds exhibited sustained anti-microbial activity over time, enhanced cell proliferation, facilitated osteogenic differentiation, and increased extracellular matrix mineralization. In addition, alkaline phosphatase (ALP), collagen type I (COL-I), and osteocalcin (OCN)-related genes and proteins were upregulated. In vivo animal implantation experiments, the anti-inflammatory effect of the Ag@3D-TiO2 scaffolds were observed using histology, and a large amount of fibrous connective tissue was present around it; the Ag@3D-TiO2 scaffolds were more bio-compatible with the surrounding tissues compared with 3D-Ti and 3D-TiO2; a large amount of uniformly distributed neoplastic bone tissue existed in their pores, and the chronic systemic toxicity test showed that the 3D-Ti, 3D-TiO2, and Ag@3D-TiO2 scaffolds are biologically safe. The goal of this study was to create a scaffold that exhibits antimicrobial properties and can aid bone growth, making it highly suitable for use in bone tissue engineering.

Preparation of Cu2+/TA/HAP composite coating with anti-bacterial and osteogenic potential on 3D-printed porous Ti alloy scaffolds for orthopedic applications.

Because of stress shielding effects, traditional titanium (Ti) alloy scaffolds have a high elastic modulus, which might promote looseness and bone disintegration surrounding the implant, increasing the likelihood of a second surgery. In contrast, 3D-printed porous Ti alloy scaffolds can reduce the scaffold weight while enhancing biocompatibility. Further, these scaffolds' porous nature allows bone tissue ingrowth as well as strong pore connectivity, which can improve nutrient absorption. Nevertheless, bare Ti alloy implants may fail because of inadequate bone integration; hence, adding a coating on the implant surface is an effective technique for improving implant stability. In this study, a composite coating comprising hydroxyapatite (HAP), chitosan (CS), tannic acid (TA) and copper ions (Cu2+) (Cu2+/TA/HAP composite coating) was prepared on the surface of 3D printed porous Ti alloy scaffolds using electrophoretic deposition. Using the standard plate count method, Live/Dead bacteria staining assay, FITC Phalloidin and 4',6-diamidino-2-phenylindole staining assay, and live/dead staining of cells we determined that the composite coating has better antibacterial properties and cytocompatibility as well as lower cytotoxicity. The Alkaline Phosphatase assay revealed that the coating results showed good osteogenesis potential. Overall, the composite coatings produced in this investigation give new potential for the application of Ti alloys in clinics.

Temporal and Spatial Beam Shaping in LPBF for Fine and Porous Ti-Alloy Structures for Regenerative Fuel Cell Applications

AbstractLaser Powder Bed Fusion (LPBF) presents itself as a potential method to produce thin porous structures, which have numerous applications in the medical and energy industries, due to its in-process pore formation capabilities. Particularly, regenerative fuel cells, which are capable of both producing and storing energy through the use of hydrogen-based electrochemical fuel cell and electrolysers, respectively, can benefit from the LPBF-induced porosity for it porous layer components in the electrode. Numerous studies have reported that process parameters, such as laser power, scan speed and hatch spacing, are key factors affecting the formation of pores in LPBF material due to their control over the energy density and melt pool formation during the build. Contemporary fibre lasers offer novel temporal and spatial beam shaping capabilities. Temporal laser control means that the laser can use pulsed wave (PW) or single point exposure (SPE), and spatial beam shaping refers to variations in the intensity distribution of the laser, which can be modulated from Gaussian to ring shape via the use of multi-core fibers. These have seldom been studied in combination with LPBF. Therefore, the aim of this study was to utilise temporal and spatial beam shaping in LPBF to produce thin porous structures. To do this, PW and SPE laser temporal strategies were utilised and the duty cycle (which relates the on and off time of the laser) was varied between 50% and 100%. Beam shape indexes 0 (Gaussian), 3 and 6 (ring) were also investigated alongside more standard LPBF process parameters such as laser power and scan speed to manufacture thin porous walls, as well as fine struts. The thinnest wall obtained was 130 μm thick, while the smallest strut had a diameter of 168 μm. The duty cycle had a clear effect on the porosity of thin walls, where a duty cycle of 50% produced the highest number of porous walls and had the highest porosity due to its ability to control the intensity of the energy density during the LPBF process. The different beam shape indexes corresponded to different spatial distribution of the power density, and hence, modifying the temperature distribution in the meltpool during the laser material interaction. Beam shape index 6 (corresponding to a ring mode with lower peak irradiance) created more porous specimens and smaller meltpool sizes, with respect to its beam size. Overall, this study showed that temporal and spatial control of the beam (through duty cycle and beam shape index) are powerful tools which can control the distribution and intensity of the energy density during the LPBF process to produce thin porous structures for energy applications.

Relative assessment of the microstructure, properties and bioactivity of 3D-printed and rolled Ti6Al4V with micro-arc oxidation (MAO) and hydrothermal (HT) treatment

The surface modification of 3D printed Ti6Al4V (3D-Ti64) and rolled Ti6Al4V (RO-Ti64) was carried out using optimized micro-arc oxidation (MAO) and hydrothermal (HT) treatment processes. The results showed that the 3D-Ti64 coating had a typical porous structure that was identical to the phase composition of the RO-Ti64 coating, and both exhibited super hydrophilic properties (contact angle of 0°). It was found that the 3D-Ti64 coating (1.40 × 10−7A/cm2, 39.38 MPa) had greater corrosion current density and adhesion strength compared to the RO-Ti64 coating (0.76 × 10−7A/cm2, 33.69 MPa). In addition, the HAP crystals formed by 3D-Ti64 and RO-Ti64 coatings after being cultured in SBF were not significantly different, indicating that both coatings had comparable in vitro bioactivity. However, the 3D-printed porous Ti64 coating formed a porous structure only around the edges, while the central region had a flocculent structure with unfinished electrolytic oxidation. Moreover, it was found that more HAP crystals were formed in the edge region after HT treatment. In short, the MAO and HT treatment parameters optimized on rolled Ti alloys can be inherited for continued use on 3D-printed Ti alloy solids. However, more considerations may need to be made for the 3D printing of porous Ti alloys.

3D-Printed Porous Tantalum Scaffold Improves Muscle Attachment via Integrin-β1-Activated AKT/MAPK Signaling Pathway.

3D-printed porous titanium (Ti) alloy scaffolds have been reported for facilitating muscle attachment in our previous study. However, the anti-avulsion ability needs to be improved. In this study, we used 3D-printed porous tantalum (Ta) scaffolds to improve muscle attachment. The differences in chemical and physical characteristics and muscle adhesion between the two scaffolds were tested and compared in the gene and protein level both in vitro and in vivo. The possible molecular mechanism was analyzed and further proved. The results showed that compared with the porous Ti alloy, porous Ta had better cell proliferation, differentiation, migration, and adhesion via the integrin-β1 (Itgb1)-activated AKT/MAPK signaling pathway in L6 rat myoblasts. When artificially down-regulated the expression of Itgb1, cell adhesion and myogenesis differentiation were affected and the phosphorylation of the AKT/MAPK signaling pathway was suppressed. In rat intramuscular implantation, porous Ta had a significantly higher muscle ingrowth rate (85.63% ± 4.97 vs 65.98% ± 4.52, p < 0.01) and larger avulsion force (0.972 vs 0.823 N/mm2, p < 0.05) than the porous Ti alloy. These findings demonstrate that the 3D-printed porous Ta scaffold is beneficial for further clinical application of muscle attachment.

Corrosion fatigue behavior of porous Cu-bearing Ti alloy fabricated by selective laser melting

Implants are commonly used to replace damaged bones in the human body. Fatigue failure is one of the most serious issues with implants. Understanding the underlying mechanisms that lead to fatigue failure is crucial in ensuring the longevity of biomaterial implants. In this study, the fatigue behavior of the porous biomaterial Ti6Al4V–6Cu, produced by selective laser melting (SLM) in air and in 0.9 wt% NaCl solution was experimentally investigated. The location of the fatigue crack (FC) initiation point on the cyclic strain curve was determined based on the fatigue cycle change. It indicates that crack initiation is accelerated in a state of high stress, and crack propagation is accelerated in a solution containing 0.9 wt% NaCl. Moreover, in an environment containing 0.9 wt% NaCl, the fatigue fracture is predominantly intergranular and partially transgranular, which is attributed to the brittle failure caused by corrosion fatigue. Additionally, in comparison to the Ti6Al4V sample, the porous Ti6Al4V–6Cu sample has a higher fatigue strength and longer fatigue life due to the effect of the Ti2Cu phase precipitated near the grain boundary and the zigzag propagation of FCs.

Improved Muscle Regeneration into a Joint Prosthesis with Mechano-Growth Factor Loaded within Mesoporous Silica Combined with Carbon Nanotubes on a Porous Titanium Alloy.

Total joint replacement (TJR) is widely applied as a promising treatment for the reconstruction of serious joint diseases but is usually characterized by critical loss of skeletal muscle attachment to metal joint prostheses, resulting in fibrous scar tissue formation and subsequent motor dysfunction. Tissue engineering technology may provide a potential strategy for skeletal muscle regeneration into metal joint prostheses. Here, a porous titanium (Ti) alloy scaffold coated with carbon nanotubes (CNTs) and mesoporous silica nanoparticles (MSNs) through electrophoretic deposition (EPD) was designed as a mechano-growth factor (MGF) carrier. This two-layered coating exhibits a nanostructured topology, excellent MGF loading, and prolonged release performance via covalent bonding to improve myoblast adhesion, proliferation and myogenic differentiation in porous Ti alloy scaffolds without cytotoxicity. The Akt/mTOR signaling pathway plays a key role in this process. Furthermore, in vivo studies show that the scaffold promotes the growth of muscle, rather than fibrotic tissue, into the porous Ti alloy structure and improves muscle-derived mechanical properties, the migration of satellite cells, and possibly immunomodulation. In summary, this nanomaterial-coated scaffold provides a practical biomaterial platform to regenerate periprosthetic muscle tissue and restore comparable motor function to that of the natural joint.

Porous Ti alloy with enhanced mechanical property prepared via chemical dealloying combined subsequent molten salt electrolysis

This paper presents a method of dealloying combined molten salt electrolysis (MSE) to prepare porous Ti alloy. The oxidation produced in dealloying process can be reduced efficiently by MSE. Meanwhile, the grain grew and the second phase of acicular nanocrystals was precipitated to enhance the mechanical properties during MSE process.

Corrosion Fatigue Behavior of Porous Cu-Bearing Ti Alloy Fabricated by Selective Laser Melting

Corrosion Fatigue Behavior of Porous Cu-Bearing Ti Alloy Fabricated by Selective Laser Melting

Low cost porous Ti-6Al-4 V structures by additive manufacturing for orthopaedic applications

Ti-based alloys have exceptional features such as super-elasticity, shape memory effect, superior bio-corrosion resistance, satisfactory Young's modulus, and brilliant bio-compatibility intended towards bio-implant usage. However, solid Ti alloys have higher mechanical strength and modulus of elasticity, hence porous structures have been used instead of solid Ti alloy to get similar results as compared to human bones. Extensive research has been done to produce porous Ti alloy scaffolds with a lower modulus of elasticity and higher compressive strength as a substitute for human bones by varying porosity and input parameters. Three different types of scaffolds (Tesseract, Star, and Octet) with 65 % porosity were modelled in Rhino 6 software and constructed through route of additive manufacturing (AM), notably Selective Laser Melting or SLM of Ti-6Al-4 V powders. Then microstructures, mechanical characteristics and porosities of the Ti alloy scaffolds were investigated. The compressive test of porous Ti-6Al-4 V scaffolds were conducted by INSTRON machine with load capacity ± 25 kN and from results it is found that the modulus of elasticity of Tesseract, Star and Octet scaffolds are 10.78 GPa, 9.29 GPa and 8.61 GPa respectively which are similar to human bones (3–30 GPa). This work primarily focuses on advantages and performances of porous titanium scaffolds to serve the needs of orthopaedic applications. Due to its higher heating rate and lower hold time, AM technologies, notably SLM, can also build scaffolds withnanoscale grain. The desired function is typically not realised by this strategy, which leads to inadequate compaction. The scaffolds made by SLM have a reasonably good pore structural accuracy but moderate mechanical strength. Star type scaffolds have a greater manufacturing ability than other scaffolds, with a smaller porosity percentage error.

Microstructure, shape memory properties, and in vitro biocompatibility of porous NiTi scaffolds fabricated via selective laser melting

In this study, three porous NiTi scaffolds with the same porosity but different pore sizes (900, 835, and 618 μm) were fabricated via selective laser melting (SLM). The microstructure, mechanical properties, shape memory properties, and in vitro biocompatibility of the different porous NiTi scaffolds were studied systematically by scanning electron microscopy, micro-computed tomography, differential scanning calorimetry, compressive testing, and in vitro cell culture experiments. The pore sizes of the SLM porous NiTi scaffolds were smaller than those of computer-aided design models owing to the existence of spatter powders, whereas the strut diameters showed the opposite tendency. Furthermore, the elastic modulus of the three NiTi scaffolds was close to that of human bones and lower than that of most previously reported porous NiTi and Ti alloys with similar porosities. Moreover, the scaffolds demonstrated better compressive strength than that of most of the reported porous NiTi alloys with similar porosities as well as better strength and fracture strain than those of human bones, particularly for scaffolds with larger pore sizes. Moreover, the best recoverable strain of 5.10% and recovery rate of 91.4% were obtained for porous NiTi scaffolds with a pore size of 900 μm owing to their minimal stress concentration during loading. The in vitro study further demonstrated that a relatively small pore size could promote the bridging growth of cells in pores, and the in vitro biocompatibility of the porous NiTi scaffolds was equivalent to that of bulk SLM NiTi. The results obtained in this study can provide guidance for the application of porous NiTi scaffolds in biological implants.

Covalent immobilization of DJK-5 peptide on porous titanium for enhanced antibacterial effects and restrained inflammatory osteoclastogenesis

Currently, implant-related bone infection characterized by aggravated infection-induced inflammatory responses and osteolysis, remains a severe challenge in orthopedic surgery, especially in patients with osteoporosis. Attempts to control such responses using biomaterials with combined immunomodulatory and anti-bacterial properties may provide novel strategies. Herein, DJK-5, a class of host defense peptides (HDPs) with established antimicrobial and immunomodulatory functions, was introduced into porous Ti alloy. Our results indicated that the DJK-5 immobilized surfaces showed intrinsically multifunctional properties, including antibacterial ability, anti-inflammation, biocompatibility and osteolysis-inhibiting properties. The results demonstrated that the antibacterial efficiency of DJK-5 functionalized surfaces was over 90 % for both Gram-positive and Gram-negative bacteria. Specifically, DJK-5 functionalized samples also possessed the excellent anti-bacterial activity against a mixture of bacterial strains, including S. aureus, S. epidermidis and P. aeruginosa, with an antibacterial rate against mixed bacteria reaching 91.36 %, as well as reduced biofilm formation. The remarkable anti-bacterial efficacy was likely based on the direct anti-bacterial effect of DJK-5, which destroyed the integrity of bacteria membranes, leading to the leakage of intracellular materials. Additionally, the immobilized DJK-5 surfaces could indirectly kill bacteria through promoted macrophage capacity to bacteria uptake. Furthermore, DJK-5 functionalized surfaces suppressed inflammatory reaction by decreasing the release of pro-inflammatory factors and increasing the secretions of anti-inflammatory factors, and thereby impeded the activation of NF-κB signal pathway, which resulted in the disruption of the actin rings and decreased Tracp5b expressions. Based on these promising findings, the multi-functional DJK-5 immobilized titanium represents an efficient alternative to realize better osseointegration in sever implant-associated bacterial infections.

Reduction of residual stress in porous Ti6Al4V by in situ double scanning during laser additive manufacturing

Selective laser melting (SLM) technology plays an important role in the preparation of porous titanium (Ti) implants with complex structures and precise sizes. Unfortunately, the processing characteristics of this technology, which include rapid melting and solidification, lead to products with high residual stress. Herein, an in situ method was developed to restrain the residual stress and improve the mechanical strength of porous Ti alloys during laser additive manufacturing. In brief, porous Ti6Al4V was prepared by an SLM three-dimensional (3D) printer equipped with a double laser system that could rescan each layer immediately after solidification of the molten powder, thus reducing the temperature gradient and avoiding rapid melting and cooling. Results indicated that double scanning can provide stronger bonding conditions for the honeycomb structure and improve the yield strength and elastic modulus of the alloy. Rescanning with an energy density of 75% resulted in 33.5%–38.0% reductions in residual stress. The porosities of double-scanned specimens were 2%–4% lower than those of single-scanned specimens, and the differences noted increased with increasing sheet thickness. The rescanning laser power should be reduced during the preparation of porous Ti with thick cell walls to ensure dimensional accuracy.

Recent Development in Beta Titanium Alloys for Biomedical Applications

β-type titanium (Ti) alloys have attracted a lot of attention as novel biomedical materials in the past decades due to their low elastic moduli and good biocompatibility. This article provides a broad and extensive review of β-type Ti alloys in terms of alloy design, preparation methods, mechanical properties, corrosion behavior, and biocompatibility. After briefly introducing the development of Ti and Ti alloys for biomedical applications, this article reviews the design of β-type Ti alloys from the perspective of the molybdenum equivalency (Moeq) method and DV-Xα molecular orbital method. Based on these methods, a considerable number of β-type Ti alloys are developed. Although β-type Ti alloys have lower elastic moduli compared with other types of Ti alloys, they still possess higher elastic moduli than human bones. Therefore, porous β-type Ti alloys with declined elastic modulus have been developed by some preparation methods, such as powder metallurgy, additive manufacture and so on. As reviewed, β-type Ti alloys have comparable or even better mechanical properties, corrosion behavior, and biocompatibility compared with other types of Ti alloys. Hence, β-type Ti alloys are the more suitable materials used as implant materials. However, there are still some problems with β-type Ti alloys, such as biological inertness. As such, summarizing the findings from the current literature, suggestions forβ-type Ti alloys with bioactive coatings are proposed for the future development.

The select of internal architecture for porous Ti alloy scaffold: A compromise between mechanical properties and permeability

With the hope to provide guidance to the design of additive manufactured porous orthopaedic implants and bone substitutes, three different topological porous structures (primitive, gyroid, bcc) with a porosity of 65% were designed and fabricated by selective laser melting using Ti-6Al-4V powders. The compressive and tensile properties of the porous scaffolds were investigated using quasi-static compression and tensile tests, respectively. Deformation behaviors of porous structures were analyzed by finite element simulation at different compression strains and loading condition. The Gyroid scaffolds have the highest compressive strength and tensile strength of 392.1 MPa and 321.3 MPa, respectively, almost two times higher than that of BCC scaffolds. Permeability of the scaffolds was measured using the falling head method and compared with the results of the computational fluid dynamics. The results showed that the permeability of the Gyroid scaffolds was about 20% that of the BCC scaffolds. It was suggested internal architecture for porous Ti alloy scaffold could significantly affect the mechanical stress and permeability.

Novel porous Ti35Zr28Nb scaffolds fabricated by powder metallurgy with excellent osteointegration ability for bone-tissue engineering applications.

Titanium (Ti) based porous alloys have been widely used as orthopedic implants. However, the successful applications of these porous Ti alloys need to have the ability to mimic the mechanical properties of natural bone. Novel porous Ti35Zr28Nb scaffolds were fabricated via powder metallurgy (PM), and the fabricated scaffold with 61.1% porosity exhibited favorable mechanical properties with a compression yield strength of 132.5 ± 3.5 MPa and an elastic modulus of 2.9 ± 0.4 GPa, which are desired mechanical properties for bone implant material applications. The extracts of the porous Ti35Zr28Nb scaffolds showed no toxic effect on cell proliferation in vitro and their cytotoxicity grade was at level 0, similar to that of as-cast pure Ti and Ti-6Al-4 V alloy. Additionally, the extracellular alkaline phosphatase (ALP) level of MC3T3-E1 indicated that the bone matrix synthesis on the porous Ti35Zr28Nb scaffolds was slightly higher than that of as-cast Ti-6Al-4 V and pure Ti alloys. After implantation in rat distal femurs for 8 weeks, the porous Ti35Zr28Nb scaffolds were surrounded by new bone tissue, and the numbers of red blood cells, white blood cells, immunocyte cells, and neutrophil cells returned to the normal levels, which indicate that the porous Ti35Zr28Nb scaffolds possess good in vivo osteointegration ability and hemocompatibility. It hence can be concluded that the PM-fabricated Ti35Zr28Nb scaffolds, which have desired mechanical properties and excellent biocompatibility and osteointegration, are a promising candidate alloy for bone-tissue engineering applications in orthopedics.

Controlled release of BMP-2 from titanium with electrodeposition modification enhancing critical size bone formation.

In this study, a porous Ti-alloy based implant with an interconnected channel structure (MAO-CaP-BMP2) is fabricated using a method combining 3D printing, microarc oxidation (MAO) treatment, and co-precipitation of Ca,P layer with BMP-2 technique. The macroporous structure with pore size of 600 μm made by 3D printing not only enhances the ingrowth of cells but also allows the formation of blood vessels inside the implant. As a result, the new bond formation is promoted. In addition, the microporous dioxide layer formed on the implant surface by MAO provides the sites for co-precipitation of Ca,P layer with BMP-2. The microstructure allows the prolonged release of BMP-2. Our results show that a sustained release of BMP-2 over 35 days is achieved for MAO-CaP-BMP2 group longer than Ti without MAO modification group and without Ca,P electrochemical deposition group. The slow release of BMP-2 at the bone/implant interface for a long period of time leads to enhancement of the osseointegration between the implant and surrounding bones. This result indicates that MAO-CaP-BMP2 is a good candidate of growth factor carrier. Successful regeneration of bone requires the concomitant processes of osteogenesis and neovascularization. MAO-CaP-BMP2 modified Ti-alloy implant is both osteoinductive and osteoconductive which can create better osteogenesis and angiogenesis. As a result, it can enhance bone formation.

DJK-5 incorporated porous titanium alloy with combined superior antibacterial efficacy and enhanced osteoblastic cell responses

Osteogenic activity is an indispensible factor that has to be considered when designing antibacterial surfaces for orthopaedic applications. To this aim, a novel DJK-5 peptide was successfully incorporated on a highly porous Ti alloy coating, through the aid of self-polymerization of dopamine. The modified surface demonstrated superior broad spectrum antibacterial efficacy against S. aureus, S. epidermidis and P. aeruginosa, respectively. Simultaneously, the incorporation of DJK-5 peptide stimulated the osteoblastic cell responses, by promoting both cell adhesion and cytoskeleton organization of MC3T3-E1 cells. Such findings would have important implication in designing implant surfaces with both antibacterial efficacy and enhanced osseo-integration potential.

In vitro and in vivo biological performance of porous Ti alloys prepared by powder metallurgy.

Titanium (Ti) and Ti-6 Aluminium-4 Vanadium alloys are the most common materials in implants composition but β type alloys are promising biomaterials because they present better mechanical properties. Besides the composition of biomaterial, many factors influence the performance of the biomaterial. For example, porous surface may modify the functional cellular response and accelerate osseointegration. This paper presents in vitro and in vivo evaluations of powder metallurgy-processed porous samples composed by different titanium alloys and pure Ti, aiming to show their potential for biomedical applications. The porous surfaces samples were produced with different designs to in vitro and in vivo tests. Samples were characterized with scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and elastic modulus analyses. Osteogenic cells from newborn rat calvaria were plated on discs of different materials: G1—commercially pure Ti group (CpTi); G2—Ti-6Al-4V alloy; G3—Ti-13 Niobium-13 Zirconium alloy; G4—Ti-35 Niobium alloy; G5—Ti-35 Niobium-7 Zirconium-5 Tantalum alloy. Cell adhesion and viability, total protein content, alkaline phosphatase activity, mineralization nodules and gene expression (alkaline phosphatase, Runx-2, osteocalcin and osteopontin) were assessed. After 2 and 4 weeks of implantation in rabbit tibia, bone ingrowth was analyzed using micro-computed tomography (μCT). EDS analysis confirmed the material production of each group. Metallographic and SEM analysis revealed interconnected pores, with mean pore size of 99,5μm and mean porosity of 42%, without significant difference among the groups (p>0.05). The elastic modulus values did not exhibit difference among the groups (p>0.05). Experimental alloys demonstrated better results than CpTi and Ti-6Al-4V, in gene expression and cytokines analysis, especially in early experimental periods. In conclusion, our data suggests that the experimental alloys can be used for biomedical application since they contributed to excellent cellular behavior and osseointegration besides presenting lower elastic modulus.

Porous TiO2-ZrO2 thin film formed by electrochemical technique to improve the biocompatibility of titanium alloy in physiological environment

Porous Ti and Ti alloys have received increasing research interest for bone tissue engineering, especially for dental and orthopaedic implants because they provide cell ingrowths and vascularization, improving of adhesion and osseointegration. The tribocorrosion process is encountered in orthopaedic and dentistry applications, since it is known that the implants are often exposed to simultaneous chemical/electrochemical and mechanical stresses. The purpose of this study was to carry out a systematic investigation of the tribo-electrochemical performance of porous TiO2–ZrO2 thin film formed by anodization of Ti–10Zr alloy surface in an artificial saliva solution and to compare the resulted performance with that of the untreated Ti–10Zr alloy surface in order to be applied for biomedical use. The in situ electrochemical technique used for investigation of tribo-electrochemical degradation was the open circuit potential (OCP) measurement performed before, during and after sliding tests. The results presented herein show that controlled anodic oxidation method can significantly improve the tribocorrosion and friction performances of Ti–10Zr alloy surface intended for biomedical applications.