Tantalum Materials Research Articles

Electrolytic Micro‐Capacitors Based on Tantalum Films for High Voltage Applications

AbstractElectrolytic capacitors are known to be fast devices with very low time constant and able to deliver high power. This class of capacitors is then an interesting technology to power miniaturized embedded electronics for Internet of Things applications. However, the current electrolytic capacitor suffers from its bulky size that does not fit with the miniaturization. To solve this issue, a proof‐of‐concept consisting of miniaturizing an electrolytic capacitor based on tantalum materials to give rise to a new class of electrolytic micro‐capacitors is proposed. To reach this ambitious objective, thin films (<100 nm) of tantalum metal (Ta), tantalum nitride (TaN), and tantalum oxide (Ta2O5) are deposited on a Si substrate by sputtering deposition method. After a careful optimization of the deposition parameters, Ta/Ta2O5 and TaN/Ta2O5 electrodes (Ta and TaN ≈45 nm and Ta2O5 ≈25 nm) and study their behaviors when biased at high voltage (>20 Volts) in aqueous electrolyte are produced. The Ta/Ta2O5 and TaN/Ta2O5 interfaces when the electrode is polarized near and beyond the breakdown voltage of the dielectric layer are carefully investigated. Polarizing the electrodes beyond the breakdown voltage are shown to result in anodization‐like mechanisms. In the case of the TaN/Ta2O5 electrode, an N‐rich porous layer grew within the Ta2O5 layer as polarization increased. A comparative study on the 2 stacked layers electrodes with different compositions (Ta/Ta2O5 and TaN/Ta2O5) but similar thicknesses (45/25 nm) is carried out: both electrodes show excellent capacitance retention of over 90% over 300 000 cycles. The frequency behavior of Ta/Ta2O5 and TaN/Ta2O5 electrodes shows that both are potential candidates in electrolytic micro‐capacitors for powering miniaturized electronics.

3D-printed porous tantalum artificial bone scaffolds: fabrication, properties, and applications.

Porous tantalum scaffolds offer a high degree of biocompatibility and have a low friction coefficient. In addition, their biomimetic porous structure and mechanical properties, which closely resemble human bone tissue, make them a popular area of research in the field of bone defect repair. With the rapid advancement of additive manufacturing, 3D-printed porous tantalum scaffolds have increasingly emerged in recent years, offering exceptional design flexibility, as well as facilitating the fabrication of intricate geometries and complex pore structures that similar to human anatomy. This review provides a comprehensive description of the techniques, procedures, and specific parameters involved in the 3D printing of porous tantalum scaffolds. Concurrently, the review provides a summary of the mechanical properties, osteogenesis and antibacterial properties of porous tantalum scaffolds. The use of surface modification techniques and the drug carriers can enhance the characteristics of porous tantalum scaffolds. Accordingly, the review discusses the application of these porous tantalum materials in clinical settings. Multiple studies have demonstrated that 3D-printed porous tantalum scaffolds exhibit exceptional corrosion resistance, biocompatibility, and osteogenic properties. As a result, they are considered highly suitable biomaterials for repairing bone defects. Despite the rapid development of 3D-printed porous tantalum scaffolds, they still encounter challenges and issues when used as bone defect implants in clinical applications. Ultimately, a concise overview of the primary challenges faced by 3D-printed porous tantalum scaffolds is offered, and corresponding insights to promote further exploration and advancement in this domain are presented.

Evolution of microstructure and grain boundaries during annealing of high-purity tantalum materials

The microstructure and texture evolution of tantalum (Ta) during annealing were studied in this work, in addition to simulating and analyzing of the grain boundary motions and their interactions using molecular dynamics simulations (MD). The results showed that the evolution of the recrystallized texture in the surface region of Ta is different from that in the core region. Coincident site lattice (CSL) is significantly related to the grain orientation and thus directly affects the recrystallization texture. MD results showed that the grain boundary mobility rate is higher at low angle grain boundaries (LAGB), which implied that the mobility rate is influenced by the tilt angle. Lower mobility rate of high angle grain boundary (HAGB) possibly caused by a large number of stabilized Σ3 grain boundaries (GBs) between them. It is shown that the inhomogeneous distribution of the recrystallization texture during the annealing process can be possibly attributed to the presence of a large number of Σ3 GBs.

Microstructure evolution and the deformation mechanism in nanocrystalline superior-deformed tantalum.

The temperature-controlled relationship between the mechanical properties and deformation mechanism of tantalum (Ta) enables the extension of its application potential in various areas of life, including energy and electronics industries. In this work, the microstructure and deformation behavior of nanocrystalline superior-deformed Ta have been investigated in a wide temperature range. The structural analysis revealed that the high-performance Ta consists of several different substructures, with an average size of about 20 nm. The tensile behavior of nanocrystalline Ta (NC-Ta) was analysed and simulated at various temperatures from 100 K to 1500 K by the molecular dynamics (MD) method. It is shown that with increasing average grain size, the elastic modulus of NC-Ta linearly increases, and the impact factor reaches a value close to 1.8. The critical grain size, as obtained from the Hall-Petch relationship, was found to be about 8.2 nm. For larger grains, the flow stress follows the Hall-Petch relationship, and the thermal behavior of twin bands determines the deformation process. On the other hand, when grains are smaller than the critical size, the relationship between the flow stress and structure transforms into the inverse Hall-Petch relationship, and the deformation mechanism is controlled by grain rotation, boundary sliding or atomic migration. The results of numerical simulations revealed that temperature significantly affects the critical grain size for the plastic deformation of NC-Ta. In addition, it is demonstrated that both the elastic modulus and dislocation density decrease with increasing temperature. These findings provide guidance for the design of polycrystalline tantalum materials with tailored mechanical properties for specific industrial applications such as heat exchangers and condensers in aerospace, bone substitutes in biomedicine, and surface acoustic wave filters or capacitors in electronics.

Synergetic treatment of waste tantalum capacitors and polyvinyl chloride by subcritical water: Tantalum recovery, benzoic acid production and dechlorination

The rapid upgrading of electronic products led to the generation of a great deal of waste tantalum capacitors (WTCs). The recovery of WTCs is of great interest due to the high-value metal tantalum and resin materials. However, it is difficult to separate/recover the materials from WTCs because of the special structure and composition. Polyvinyl chloride (PVC) waste with high level of chlorine could result in severe corrosion and emission of chlorinated pollutants in the conventional disposal process. In this study, a synergetic and high-efficiency treatment of WTCs and PVC by subcritical water (SubCW) process was developed based on the interaction of the two kinds of wastes. The interaction between WTCs and PVC in SubCW could significantly reduce the treatment temperature and shorten the reaction time for recovering high-purity metal tantalum from WTCs, and it could also markedly improve the dechlorination efficiency (DE) of PVC. The optimized conditions for the synergetic treatment of WTCs and PVC were 325 ℃, 30 min, solid-to-liquid ratio of 1:5 g/mL, and PVC-to-WTCs ratio of 6:1 g/g. The resin conversion efficiency (RCE) of WTCs and the DE of PVC could reach 100% and 97.39% under the optimized conditions. The HCl released from PVC in SubCW could significantly promote the acid-catalytic hydrolysis of resin materials in WTCs and resulted in the production of abundant phenol/phenol derivates. In turn, hydroxyl functional group of phenol/phenol derivates could enhance the dechlorination of PVC by promoting the hydroxyl substitution reaction pathway. High level of benzoic acid (72.52%) could be obtained from the interaction between the decomposition products of WTCs and PVC by radical and oxidation reactions. The SubCW synergetic process developed in this study provided a high-efficiency and low-energy strategy for metal tantalum recovery, benzoic acid production, and dechlorination from WTCs and PVC wastes.

The role of formamidine acetate as a complexing agent in the chemical mechanical polishing process of Ta-based barrier layers for through-silicon vias wafers

The complex agent can form a soluble complex with tantalum to improve the removal rate of tantalum (Ta), but the removal rate of tantalum is less than 1000 Å/min when the traditional complex agents such as citric acid, acetic acid, phosphoric acid, ammonium salt and oxalic acid are added to the slurry, which cannot meet the requirements of through-silicon via (TSV) process. Due to the various bonding forms of amidine and the easy modification of the substituent group on the terminal nitrogen atom, the metal complexes of amidine have different stereo effects and electronic properties, and are called "universal ligands". Formamidine acetate (FA) is a new complexing agent with great potential, which is suitable for the removal of TSV tantalum materials. In order to improve the rate selection ratio of Ta and copper (Cu) in the chemical mechanical polishing (CMP) of TSV wafer barrier materials, the effect of FA as a complexing agent on the removal rate of Ta and Cu and the rate selection ratio was investigated under the conditions of working pressure of 3 psi, polishing head speed of 87 r/min, polishing disk speed of 93 r/min, and flow rate of 300 mL/min. The complexation mechanism of FA on Ta and Cu was investigated by electrochemistry, X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and density functional theory (DFT), and the surface quality before and after polishing was compared by using atomic force microscope (AFM). The results showed that with an FA concentration of 1.5 wt%, the removal rates of Ta and Cu were 1503 Å/min and 516 Å/min respectively, which verified the obvious effect of FA on improving the rate selection ratio of Ta and Cu. Surface roughness for both metals decreased from pre-polishing values of 0.793 nm to post-polishing values of 0.210 nm for Ta; from pre-polishing values of 4.32 nm to post-polishing values of 0.381 nm for Cu indicating significant improvement in surface quality after treatment with FA.

Research progress and clinical translation of three-dimensional printed porous tantalum in orthopaedics.

With continuous developments in additive manufacturing technology, tantalum (Ta) metal has been manufactured into orthopaedic implants with a variety of forms, properties and uses by three-dimensional printing. Based on extensive research in recent years, the design, processing and performance aspects of this new orthopaedic implant material have been greatly improved. Besides the bionic porous structure and mechanical characteristics that are similar to human bone tissue, porous tantalum is considered to be a viable bone repair material due to its outstanding corrosion resistance, biocompatibility, bone integration and bone conductivity. Numerous in vitro, in vivo, and clinical studies have been carried out in order to analyse the safety and efficacy of these implants in orthopaedic applications. This study reviews the most recent advances in manufacturing, characteristics and clinical application of porous tantalum materials.

Separation of waste tantalum capacitors by supercritical methanol: Recovery of high-purity metal tantalum and producing of bisphenol/diphenyl chemicals

With the rapid upgrading of electronic products, a large amount of waste tantalum capacitors (WTC) were generated. The recovery and purification of the WTC attracted widespread interest due to the high-value rare metal tantalum and resin materials. However, the recovery and purification of the WTC was difficult due to the heterogeneous complex composition including metal tantalum, nickel–iron, silver, and organic resins. High-temperature and the potential formation of the hazardous compounds such as dioxins are the main bottleneck of the traditional thermochemical treatment methods for the WTC. In this study, a novel and high-efficiency supercritical methanol (SCM) process was developed for the recovery and purification of tantalum and resins from the WTC based on the low hydrogen bonding numbers and dielectric constant of methanol. The tantalum could be recovered as pure metal tantalum, and the resins were converted into oil by the SCM process. The temperature, time, and solid-to-liquid ratio have significant effect on the conversion ratio of resins. Under the optimal SCM conditions (350 °C, 90 min, and 1:20 g/mL), 97.1% of the external resins of capacitor were converted into oil (99.5%) and gas (0.5%), and the high-purity metal tantalum could be fully recovered. GC–MS and FT-IR analysis showed that the products converted from the resins in the WTC mainly included high level of aromatic derivatives of bisphenol and diphenyl (88.02%), which could be used as fuel or chemical feedstock after proper upgrade. The SCM method is an environmentally friendly process for the recovery and purification of the WTC without any discharge of waste water and off-gas due to that the treatment medium methanol could be recycled. The conversion mechanism of resins in the WTC by the SCM process was proposed.

Metal Crystal/Polycrystal Plasticity and Strengths

A brief historical sketch is given of Taylor’s dislocation density-based model description, leading to the prediction of a parabolic, tensile, stress–strain curve for the plastic deformation of aluminum. The present focus is on additional results or analyses obtained on the subject for crystal/polycrystal strain hardening. Our current understanding of such material behavior is attributed to post-Taylor descriptions of sequential deformation stages in stress–strain measurements that are closely tied to specific dislocation interaction and reaction mechanisms. A schematic comparison is given for individual face-centered cubic (fcc), body-centered cubic (bcc), and hexagonal close-packed (hcp) crystal curves and to related strength properties determined for individual crystals and polycrystalline material. For the fcc case, an example sessile dislocation reaction is described based on a stereographic projection. Then, quantitative constitutive-relation-based assessments are presented for the tensile strain hardening leading to the plastic instability behaviors of copper and tantalum materials.

Constitutive relations for slip and twinning in high rate deformations: A review and update

Constitutive relations for slip and deformation twinning behaviors of a number of metals, including α-titanium, copper, α-iron, and tantalum materials, are described over a very large range in imposed strain rates. The focus is on application to higher-rate Taylor (solid cylinder) impact tests, split-Hopkinson pressure bar measurements, and shock as compared with ramp-type isentropic compression tests and including simulations of the corresponding dislocation-based deformation behaviors.

REVIEW OF APPLICATION AND RESEARCH BASED ON COLD SPRAY COATING MATERIALS

Cold spray technology is an advanced spray technology, and its technical principle is the same as that of additive manufacturing technology. Cold spraying technology combines multiple advantages in the spraying field: not only can the deposition of thick coatings be achieved, but the coatings prepared by this technology have the characteristics of high density, low oxygen content, good mechanical properties of the coating surface, and high deposition efficiency. Cold spraying technology can prepare corrosion-resistant coatings, high-temperature resistant coatings, wear-resistant coatings, conductive coatings, anti-oxidation coatings, and other functional coatings. After decades of development and exploration, cold spraying technology is preparing metal coatings. The application is very wide and the process is mature; the same cold spray technology can also prepare non-metallic coatings. Mainly to immerse repair and protect the surface of metal alloy parts and a small part of non-metal parts, so that these parts have better mechanical properties and mechanical behavior. This article mainly reviews the application of cold spray technology in the field of spray materials and summarizes the existing conventional metal series, rare metal series and non-metal material, conventional non-ferrous metals: copper, titanium, aluminum and nickel. Metal materials are currently widely used in the field of cold spraying. Among them, titanium-based metals restrict their applications due to their own properties; rare metals: tungsten, tantalum, and niobium-based metal materials. The application of rare metals in cold spraying is still in its infancy stage; non-metallic materials: polymer materials and ceramic powder materials, non-metallic materials have the characteristics of surface modification and strengthening technology, but also have low oxygen content, low thermal stress, high density, good bonding strength, in the deposition process and the substrate will not change the advantages of physical organization structure. Finally, the existing problems of rare metal materials and non-metal materials are raised.

Evaluation of the bone morphology around four types of porous metal implants placed in distal femur of ovariectomized rats

BackgroundTo compare structural features of the femoral bone of ovariectomized and non-ovariectomized rats after implantation of porous materials (TANTALUM, CONCELOC, TTM, ATLANT).MethodsExperiments were carried out on 56 white laboratory female rats aged 6 months. Rats were randomly assigned into groups: sham-operated control group (SH) or ovariectomy group (OVX). Four different commercial implant materials (TTM, CONCELOC, TANTALUM, ATLANT) were placed into the defects (diameter 2.5 mm, depth 3.0 mm) in the distal metaphysis of femurs. Rats were sacrificed 45 days after surgery. Histological study was performed and the percentage of the bone area (BA%) around the implant at a distance of 500 μm in the cancellous area was measured.ResultsFormation of mature bone tissue of varying degrees around all of the implants was detected. In OVX rats cancellous bone defect zone was characterized by a high density of osteocytes on the surface. In the SH group, no differences in BA% among implant materials were found. In OVX rats, the BA% around ATLANT implants was 1.5-time less (p = 0.002) than around TANTALUM. The BA% around the rest of the materials was not statistically different.ConclusionsBone formation around the studied porous titanium and tantalum materials in the osteoporosis model was lower than in normal bone. There were differences in bone formation around the different materials in the osteoporosis model, while in the normal bone model, these differences were absent.

Dislocation Mechanics of Extremely High Rate Deformations

High strain rate simulations were performed using the multiscale dislocation dynamic plasticity (MDDP) method to calculate different rise times and load durations in mimicking high deformation rate shock as compared with isentropic (ramp) testing of α-iron and tantalum materials. Smaller differences than expected were found between the two loading behaviors and attributed to the shock loading being relatively weak. Comparisons were also made with thermal activation strain rate analysis (TASRA), phonon drag and dislocation generation predictions for the behaviors.

The progress on physicochemical properties and biocompatibility of tantalum-based metal bone implants

Repair, reconstruction, and replacement of congenital malformations, either in case of exogenous or iatrogenic tissue and organ defects, requires utilization of a large number of personalized biomaterials. In recent decades, the improvement of people’s quality of life and the prolongation of life expectancy have promoted the development of medical and material science. In addition to the traditionally used stainless steel, other materials such as cobalt–chromium alloy, pure titanium, titanium alloy, and the newly alloy materials continue to emerge, such as tantalum-based alloy materials which have been used in clinic, especially the application of porous tantalum trabecular metal in orthopedics. This paper which has provided good preliminary works for the development of tantalum biomaterials with more advantages in the future such as tantalum dental implants summarizes in detail the progress of tantalum materials in physicochemical properties and biocompatibility in recent years. From the comparison of surface passivation films of different metals in different environments, the electrochemical corrosion behavior of tantalum, the release of different metal ions and the damage to cells, it is concluded that tantalum has excellent corrosion resistance. Besides, the excellent biocompatibility of tantalum metals concluded by cytology, molecular biology, protein adsorption experiment, and hematology experiment, as well as regular follow-up observation of patients with porous tantalum trabecular metal in clinic. The excellent corrosion resistance and biocompatibility of the tantalum metal have a very wide prospect in clinical application.

In vitro response of bone marrow mesenchymal stem cells (hBMSCs) on laser-induced periodic surface structures for hard tissue replacement: Comparison between tantalum and titanium

This study investigates the biological response of tantalum and titanium materials with Laser Induced Periodic Surface Structures (LIPSS) produced by a femtosecond laser at a wavelength of 1030 nm. Periodic surface nanostructures were formed by laser irradiation using a laser energy slightly above the damage threshold fluence for titanium and tantalum; pulses with a 500 fs pulse duration at a high repetition rate were applied to smooth polished tantalum and titanium surfaces with an original roughness value of 3.9 ± 0.2 nm and 3.1 ± 0.2 nm, respectively. We have demonstrated that LIPSS are an efficient option to increase osteoblastic differentiation of hBMSCs in vitro on titanium and tantalum surfaces. LIPSS modification created a statistically significant increase in cell metabolism; the best values were observed using an MTT assay. Similar improvements in inflammatory response to the material (IL-6 and TNF-alfa values) were also observed. Results also show that collagen is produced in greater quantities and cells differentiate to osteoblasts easily. These differences are seen from the beginning until the end point of the in-vitro trial over a 20 day duration.

Hundred years development and future prospect of the material science for hernia

Inguinal hernia is a defect disease in the abdominal wall. Surgeons have tried various ways to repair the defect for more than 100 years. The traditional herniorrhaphy destroys the normal anatomical structure, and the recurrence rate is quite high. After that, surgeons began to repair the defects with prostheses, from the initial use of rough metal materials such as silver, tantalum, stainless steel, to nylon, fiberglass, silicone rubber and other non-metallic materials, and also from artificial synthetic polymer non-absorbable materials such as polypropylene, polyester, ePTFE, to synthetic absorbable materials such as polyglycolic acid and the acellular extracellular matrix derived from biological meshes. However, these prostheses still can not meet the diverse needs of patients. Thus, multifunctional composite prostheses consisting of two or more materials were born, and various types of composite prostheses, stem cell coating meshes, 3D meshes, microstructure meshes were developed. The repair method evolved from traditional hernia repair to tension-free hernia repair and laparoscopic hernia repair. Surgeons are dedicated to finding idealized meshes for the perfect repair of defects, while considering postoperative complications, patient's quality of life, long-term efficacy and other issues. In the face of a wide variety of repair materials, the choice of surgeons is blind, and there is no standard to determine which prostheses are suitable for patients. Therefore, we have combed the development of different types of prostheses, summarized the development process of hernia repair materials for the past 100 years, and put forward the prospects for future development of prostheses, in order to provide reference for the selection of prostheses.

Niobium alloys for the chemical process industry

Tantalum materials have been used extensively in some of the most demanding applications in the chemical process industry (CPI) for many years. However, tantalum and tantalum alloys are not only expensive relative to other corrosion resistant metals such as zirconium, but can be considered excessive for many less demanding applications. Niobium is used on a limited basis in the CPI due to its low mechanical strength and poor corrosion resistance relative to tantalum and zirconium. Consequently H.C. Starck undertook a project to develop new niobium alloys with improved corrosion resistance as well as improved mechanical properties. Initial results have shown these niobium alloys have corrosion resistance significantly improved over pure niobium and zirconium with mechanical properties comparable to Ta-3W, the standard tantalum based CPI alloy.

Effect of heat input on microstructure and strength of welds in tantalum and niobium alloys

Welding of niobium and tantalum materials is currently conducted in vacuum or inert gas chambers, which limits the size of the equipment to be produced. The objective of this study is to investigate the means to make TIG welding on these materials in atmospheric environment and analyse the effect of heat input on the properties of welds. It was found that it is possible to make TIG welds on these materials in atmospheric environment, provided that adequate protection is ensured on the face and root sides of welds. The increase of weld heat input coarsens the microstructure in melted and heat affected zones of both materials; increases also hardness in melted zones and tensile strength of welds, and there is not an obvious loss of ductility in heat affected zones.

Do new materials improve acetabular fixation and reduce wear? Commentary on an article by David C. Ayers, MD, et al.: "radiostereometric analysis study of tantalum compared with titanium acetabular cups and highly cross-linked compared with conventional liners in young patients undergoing total hip replacement".

Commentary The bearing articulation remains the nemesis of total hip arthroplasty. Obtaining and maintaining component stability and minimizing wear of the articulation represent the two most important factors for the longevity of any hip replacement. This article by Ayers et al. evaluates the stability of two different types of cementless fixation, a titanium fiber mesh compared with ultra-porous tantalum. The authors further investigate wear of an ultra-high molecular weight conventional polyethylene liner compared with a highly cross-linked polyethylene liner. This article represents a sequel to a previously published two-year follow-up evaluation of noncemented total hip arthroplasty acetabular migration and polyethylene wear as determined by radiostereometric analysis (RSA)1. A total of forty-six young, active individuals undergoing primary total hip arthroplasty were randomized into four cohorts: ultra-high molecular weight conventional polyethylene liner and titanium cup, highly cross-linked polyethylene liner and titanium cup, ultra-high molecular weight conventional polyethylene liner and tantalum cup, and highly cross-linked polyethylene liner and tantalum cup. There were no clinical or non-RSA radiographic differences among the groups. RSA demonstrated significantly less femoral head penetration, a surrogate for polyethylene wear, in the highly cross-linked polyethylene liners compared with ultra-high molecular weight conventional polyethylene liners by an order of magnitude. There was no significant difference in proximal migration between the titanium and tantalum acetabular components through five years of follow-up. The type of polyethylene liner or acetabular component had no effect on patient activity, pain, and well-being, which were maximized by six months following surgical intervention. The strength of this article is that it is a prospective, randomized, blinded study utilizing a very sophisticated technology, namely RSA, to obtain precise measurements of component micromotion relative to the bone that is otherwise undetectable by routine radiographs and to measure femoral head penetration2. The radiodense tantalum cups obscure the identification of the center of the femoral head with use of edge detection. Therefore, Ayers et al. developed a novel method known as the “fictive femoral head” to assess wear. This method is based on the identification of two radiopaque tantalum markers attached to the stem proximally and a priori knowledge of the femoral head and stem configuration of the inserted total hip replacement. From a series of radiographs, a stem configuration library was created, which provided geometrical information used to place a fictive femoral head center in three-dimensional space. This fictive femoral head center will be used by the RSA software. Although others have reported a substantial decrease in the wear of highly cross-linked polyethylene3, this article clearly shows the superiority of highly cross-linked polyethylene over conventional polyethylene, with a tenfold reduction in wear. Wear rates from one to five years were 0.04 mm/yr for ultra-high molecular weight conventional polyethylene liners and 0.004 mm/yr for highly cross-linked polyethylene liners. With respect to fixation, Ayers et al. demonstrated excellent fixation of both titanium mesh and tantalum acetabular components, as has been previously documented4. At the five-year follow-up, the median migration (and standard error) was 0.05 ± 0.20 mm proximally for titanium mesh cups and 0.21 ± 0.05 mm for tantalum cups. No implants were shown to be loose on radiographs. There was no evidence of osteolysis and no revisions were performed through five years of follow-up. The take-home points from this article are as follows. With use of femoral head penetration according to precise RSA measurements as a surrogate for wear, highly cross-linked polyethylene demonstrates ten times lower wear than ultra-high molecular weight conventional polyethylene at up to five years of follow-up3. Titanium mesh and tantalum (Trabecular Metal; Zimmer) materials provide excellent cementless fixation for acetabular components with little evidence of clinically relevant migration as measured by sophisticated RSA technology at up to five years of follow-up4. These results cannot and should not be extrapolated to other types of porous and ultra-porous cementless fixation.

Biofunctionalization strategies on tantalum-based materials for osseointegrative applications.

The use of tantalum as biomaterial for orthopedic applications is gaining considerable attention in the clinical practice because it presents an excellent chemical stability, body fluid resistance, biocompatibility, and it is more osteoconductive than titanium or cobalt-chromium alloys. Nonetheless, metallic biomaterials are commonly bioinert and may not provide fast and long-lasting interactions with surrounding tissues. The use of short cell adhesive peptides derived from the extracellular matrix has shown to improve cell adhesion and accelerate the implant’s biointegration in vivo. However, this strategy has been rarely applied to tantalum materials. In this work, we have studied two immobilization strategies (physical adsorption and covalent binding via silanization) to functionalize tantalum surfaces with a cell adhesive RGD peptide. Surfaces were used untreated or activated with either HNO3 or UV/ozone treatments. The process of biofunctionalization was characterized by means of physicochemical and biological methods. Physisorption of the RGD peptide on control and HNO3-treated tantalum surfaces significantly enhanced the attachment and spreading of osteoblast-like cells; however, no effect on cell adhesion was observed in ozone-treated samples. This effect was attributed to the inefficient binding of the peptide on these highly hydrophilic surfaces, as evidenced by contact angle measurements and X-ray photoelectron spectroscopy. In contrast, activation of tantalum with UV/ozone proved to be the most efficient method to support silanization and subsequent peptide attachment, displaying the highest values of cell adhesion. This study demonstrates that both physical adsorption and silanization are feasible methods to immobilize peptides onto tantalum-based materials, providing them with superior bioactivity.