-
Materials Science & Engineering. C,... Oct 2013A new biodegradable magnesium-zinc-strontium (Mg-Zn-Sr) alloy was developed and studied for medical implant applications. This first study investigated the alloy...
A new biodegradable magnesium-zinc-strontium (Mg-Zn-Sr) alloy was developed and studied for medical implant applications. This first study investigated the alloy processing (casting, rolling, and heat treatment), microstructures, mechanical properties, and degradation properties in simulated body fluid (SBF). Aging treatment of the ZSr41 alloy at 175 °C for 8h improved the mechanical properties when compared to those of the as-cast alloy. Specifically, the aged ZSr41 alloy had an ultimate tensile strength of 270 MPa, Vickers hardness of 71.5 HV, and elongation at failure of 12.8%. The mechanical properties of the ZSr41 alloy were superior as compared with those of pure magnesium and met the requirements for load-bearing medical implants. Furthermore, the immersion of the ZSr41 alloy in SBF showed a degradation mode that progressed cyclically, alternating between pitting and localized corrosion. The steady-state average degradation rate of the aged ZSr41 alloy in SBF was 0.96 g/(m(2)·hr), while the pH of SBF immersion solution increased. The corrosion current density of the ZSr41 alloy in SBF solution was 0.41 mA/mm(2), which was much lower than 1.67 mA/mm(2) for pure Mg under the same conditions. In summary, compared to pure Mg, the mechanical properties of the new ZSr41 alloy improved while the degradation rate decreased due to the addition of Zn and Sr alloying elements and specific processing conditions. The superior mechanical properties and corrosion resistance of the new ZSr41 alloy make it a promising alloy for next-generation implant applications.
Topics: Alloys; Biodegradation, Environmental; Biomedical Technology; Body Fluids; Corrosion; Hardness; Hydrogen-Ion Concentration; Materials Testing; Mechanical Phenomena; Microscopy, Electron, Scanning; Spectrometry, X-Ray Emission; Surface Properties; Tensile Strength; X-Ray Diffraction
PubMed: 23910262
DOI: 10.1016/j.msec.2013.04.054 -
Scientific Reports Oct 2017Magnesium (Mg) alloys are promising materials for biodegradable implants, but their clinical translation requires improved control over their degradation rates. Proteins...
Magnesium (Mg) alloys are promising materials for biodegradable implants, but their clinical translation requires improved control over their degradation rates. Proteins may be a major contributing factor to Mg alloy degradation, but are not yet fully understood. This article reports the effects of fetal bovine serum (FBS), a physiologically relevant mixture of proteins, on Mg and Mg alloy degradation. FBS had little impact on mass loss of pure Mg during immersion degradation, regardless of whether or not a native oxide layer was present on the sample surface. FBS reduced the mass loss of Mg-Yttrium (MgY) alloy with an oxidized surface during immersion degradation, but increased the mass loss for the same alloy with a metallic surface (surface oxides were removed). FBS also influenced the mode of degradation by limiting the depth of pit formation during degradation processes on commercially pure Mg with metallic or oxidized surfaces and on MgY alloy with oxidized surfaces. The results demonstrated that serum proteins had significant interactions with Mg-based biodegradable metals, and these interactions may be modified by alloy composition and processing. Therefore, proteins should be taken into account when designing experiments to assess degradation of Mg-based implants.
Topics: Absorbable Implants; Alloys; Animals; Blood Proteins; Cattle; Corrosion; Humans; Hydrogen-Ion Concentration; Magnesium; Materials Testing; Microscopy, Electron, Scanning; Oxidation-Reduction; Serum; Surface Properties
PubMed: 29084971
DOI: 10.1038/s41598-017-14479-6 -
Biomaterials Advances Oct 2023Alloying and structural design provide flexibility to modulate performance of biodegradable porous implants manufactured by laser powder bed fusion (L-PBF). Herein, bulk...
Alloying and structural design provide flexibility to modulate performance of biodegradable porous implants manufactured by laser powder bed fusion (L-PBF). Herein, bulk Zn-0.8Li-0.1Mg was first fabricated to indicate the influence of the ternary alloy system on strengthening effect. Porous scaffolds with different porosities, including 60 % (P60), 70 % (P70) and 80 % (P80), were designed and fabricated to study the influence of porosity on mechanical properties, in vitro degradation behavior, biocompatibility and osteogenic ability. Pure Zn (Zn-P70) scaffolds with a porosity of 70 % were utilized for the comparison. The results showed Zn-0.8Li-0.1Mg bulks had an ultimate tensile strength of 460.78 ± 5.79 MPa, which was more than 3 times that of pure Zn ones and was the highest value ever reported for Zn alloys fabricated by L-PBF. The compressive strength (CS) and elastic modulus (E) of scaffolds decreased with increasing porosities. The CS of P70 scaffolds was 24.59 MPa, more than 2 times that of Zn-P70. The weight loss of scaffolds during in vitro immersion increased with increasing porosities. Compared with Zn-P70, a lower weight loss, better biocompatibility and improved osteogenic ability were observed for P70 scaffolds. P70 scaffolds also exhibited the best biocompatibility and osteogenic ability among all the used porosities. Influence mechanism of alloying elements and structural porosities on mechanical behaviors, in vitro biodegradation behavior, biocompatibility and osteogenic ability of scaffolds were discussed using finite element analysis and the characterization of degradation products. The results indicated that the proper design of alloying and porosity made Zn-0.8Li-0.1Mg scaffolds promising for biodegradable applications.
Topics: Materials Testing; Alloys; Tissue Scaffolds; Absorbable Implants; Zinc
PubMed: 37562158
DOI: 10.1016/j.bioadv.2023.213571 -
Acta Biomaterialia Jan 2016Previous studies indicated that local delivery of strontium effectively increased bone quality and formation around osseointegrating implants. Therefore, implant...
UNLABELLED
Previous studies indicated that local delivery of strontium effectively increased bone quality and formation around osseointegrating implants. Therefore, implant materials with long-lasting and controllable strontium release are avidly pursued. The central objective of the present study was to investigate the in vivo biocompatibility, metabolism and osteogenic activity of the bioabsorbable Mg-1Sr (wt.%, nominal composition) alloy for bone regeneration. The general corrosion rate of the alloy implant as a femoral fracture fixation device was 0.55±0.03mm·y(-1) (mean value±standard deviation) in New Zealand White rabbits which meet the bone implantation requirements and can be adjusted by material processing methods. All rabbits survived and the histological evaluation showed no abnormal physiology or diseases 16 weeks post-implantation. The degradation process of the alloy did not significantly alter 16 primary indexes of hematology, cardiac damage, inflammation, hepatic functions and metabolic process. Significant increases in peri-implant bone volume and direct bone-to-implant contact (48.3%±15.3% and 15.9%±5.6%, respectively) as well as the expressions of four osteogenesis related genes (runt-related transcription factor 2, alkaline phosphatase, osteocalcin, and collagen, type I, alpha 1) were observed after 16 weeks implantation for the Mg-1Sr group when compared to the pure Mg group. The sound osteogenic properties of the Mg-1Sr alloy by long-lasting and controllable Sr release suggesting a very attractive clinical potential.
STATEMENT OF SIGNIFICANCE
Sr (strontium) has exhibited pronounced effects to reduce the bone fracture risk in osteoporotic patients. Nonetheless, long-lasting local Sr release is hardly achieved by traditional methods like surface treatment. Therefore, a more efficient Sr local delivery platform is in high clinical demand. The stable and adjustable degradation process of Mg alloy makes it an ideal Sr delivery platform. We combine the well-known osteogenic properties of strontium with magnesium to manufacture bioabsorbable Mg-1Sr alloy with stable Sr release based on our previous studies. The in vitro and in vivo results both showed the alloy's suitable degradation rate and biocompatibility, and the sound osteogenic properties and stimulation effect on bone formation suggest its very attractive clinical potential.
Topics: Absorbable Implants; Alloys; Animals; Bone-Implant Interface; Cells, Cultured; Gene Expression Regulation; Humans; Magnesium; Osteogenesis; Rabbits; Strontium
PubMed: 26577986
DOI: 10.1016/j.actbio.2015.11.014 -
Acta Biomaterialia Oct 2012The aim of this study is to investigate and demonstrate the mechanical and corrosive characteristics of the neodymium-containing magnesium alloy MgNd2 (Nd2), which can...
The aim of this study is to investigate and demonstrate the mechanical and corrosive characteristics of the neodymium-containing magnesium alloy MgNd2 (Nd2), which can be used as a resorbable implant material, especially in the field of stenting applications. To determine the mechanical characteristics of Nd2, tensile and compression tests were initially carried out in the hot extruded state. Here a unique elongation ratio (~30%) of the alloy could be observed. Subsequent T5 and T6 heat treatments were arranged to reveal their effect on the alloy's strengths and elongation values. The general degradation behaviour of Nd2 in a 0.9% NaCl solution was investigated by means of polarization curves and hydrogen evolution. In addition to this, by using various in vivo parameters, a corrosion environment was established to determine the alloy's degradation in vitro. Here, the mass loss per day in (MgF(2) and Bioglass)-coated and uncoated states and the corresponding maximum forces resulting from subsequent three-point bending tests revealed slow and steady corrosion behaviour. The cell viability and proliferation tests carried out on L-929 and MSC-P5 cells also showed good results. The mechanical and corrosive characteristics determined, as well as the in vitro test results obtained within the scope of this study, led to the development and successful in vivo testing of an MgF(2)-coated Nd2 mucosa stent which was introduced as an appropriate resorbable application.
Topics: Alloys; Animals; Biocompatible Materials; Bromodeoxyuridine; Cell Line; Cell Proliferation; Cell Survival; Coated Materials, Biocompatible; Compressive Strength; Corrosion; Electricity; Electron Probe Microanalysis; Hot Temperature; Humans; Materials Testing; Mice; Microscopy, Electron, Scanning; Neodymium; Prostheses and Implants; Spectrometry, X-Ray Emission; Tensile Strength
PubMed: 22676917
DOI: 10.1016/j.actbio.2012.05.024 -
Dental Materials : Official Publication... Feb 2017Low modulus β-titanium alloys with non-toxic alloying elements are envisaged to provide good biocompatibility and alleviate the undesired stress shielding effect. The...
OBJECTIVES
Low modulus β-titanium alloys with non-toxic alloying elements are envisaged to provide good biocompatibility and alleviate the undesired stress shielding effect. The objective of this study is to fundamentally elucidate the biological response of novel high strength-low elastic modulus Ti2448 alloy through the study of bioactivity and osteoblast cell functions.
METHODS
Characterization techniques such as SEM, EDX, XRD, and fluorescence microscopy were utilized to analyze the microstructure, morphology, chemical composition, and cell adhesion. The cellular activity was explored in terms of cell-to-cell communication involving proliferation, spreading, synthesis of extracellular and intracellular proteins, differentiation, and mineralization.
RESULTS
The formation of fine apatite-like crystals on the surface during immersion test in simulated body fluid confirmed the bioactivity of the surface, which provided the favorable osteogenic microenvironment for cell-material interaction. The proliferation and differentiation of pre-osteoblasts and their ability to form a well mineralized bone-like extracellular matrix (ECM) by secreting bone markers (ALP, calcium, etc.) over the surface point toward the determining role of unique surface chemistry and surface properties of the Ti-24Nb-4Zr-8Sn (Ti2448) alloy in modulating osteoblasts functions.
SIGNIFICANCE
These results demonstrated that the low modulus (∼49GPa) Ti2448 alloy with non-toxic alloying elements can be used as a potential dental or orthopedic load-bearing implant material.
Topics: Alloys; Biocompatible Materials; Elastic Modulus; Materials Testing; Osteoblasts; Surface Properties; Titanium
PubMed: 27889088
DOI: 10.1016/j.dental.2016.11.005 -
Journal of Biomedical Materials... Jan 2023Limited material transport, causing gas cavities formation, is commonly observed during the degradation of magnesium implants, yet its effects on corrosion are not...
Limited material transport, causing gas cavities formation, is commonly observed during the degradation of magnesium implants, yet its effects on corrosion are not understood. Herein, a bespoke cell was designed, allowing for the incorporation of an additional agarose layer above the corroding magnesium sample. This design replicates the limited material transport in vitro and enables us to understand its influence on corrosion of magnesium alloys. This work investigated the influence of varying thickness of agarose (0-0.9 mm) on the corrosion of Mg-Zn-Zr magnesium alloy maintained at 37°C in phosphate-buffered saline (PBS). The introduction of agarose slowed transport of material away from the corroding magnesium surface, including the evolved hydrogen forming a gas cavity. It has been found that an initial increase in the agarose thickness (or the reduction in material transport) of 0.3 mm leads to an increase in the corrosion rate of the magnesium alloy by 62%. However, with a further increase in agarose thickness from 0.3 to 0.9 mm, the corrosion rate decreases by 37%. This observation has been attributed to the accumulation of, and competition between, chloride and hydroxide ions near the alloy's surface. In the presence of materials barrier, hydrogen measurement is no longer a reliable method for the measurement of corrosion rates. This study underscores the importance of the consideration of limited material transport during the in vitro corrosion tests of biomedical implants.
Topics: Alloys; Corrosion; Magnesium; Hydrogen; Sepharose; Materials Testing
PubMed: 36125179
DOI: 10.1002/jbm.a.37446 -
Proceedings of the Institution of... Dec 2022Recently, AZ31B magnesium alloy has been widely employed in automotive, aerospace, and bio implant industries due to its light-weight and biocompatibility properties....
Recently, AZ31B magnesium alloy has been widely employed in automotive, aerospace, and bio implant industries due to its light-weight and biocompatibility properties. However, the equilibrium of ductility and strength of this material and the negativity brought by its poor wear behavior have limited its versatile use. Friction stir processing (FSP) has been commonly used as severe plastic deformation method for improving mechanical and tribological properties of metal sheets. The effect of this method on the biocompatibility of materials is a matter of curiosity that should be emphasized. So, the present study aims to investigate the effect of friction stir process on the mechanical, tribological, and biocompatibility properties of AZ31B magnesium alloy. It is observed that FSP enhanced the tensile properties of the alloy but decreased its elongation. It was determined that the base material exhibited ductile character on the fracture surface of the specimens, and mixed ductile/brittle fracture was evident with the FSP. In the FSP zone, the hardness value was improved by 17% compared to the base material. Also, the wear performance of the alloy enhanced in ambient air and Simulated Body Fluid (SBF) solution. Wear properties in SBF solution were better due to less adhesive bonds between the friction surfaces. This assessment was supported by SEM images of the wear path and surface of counter bodies. On the other hand, FSPed AZ31B alloy materials with improved strength properties were not cytotoxic for human gingival fibroblasts, and these results may suggest that the materials are safe for clinical uses.
Topics: Humans; Magnesium; Friction; Pilot Projects; Materials Testing; Surface Properties; Alloys
PubMed: 36345892
DOI: 10.1177/09544119221135687 -
Journal of Biomedical Materials... Jul 2017Spinal implants are made from a variety of materials to meet the unique mechanical demands of each application. However, the medical device community has raised concern...
Spinal implants are made from a variety of materials to meet the unique mechanical demands of each application. However, the medical device community has raised concern about mixing dissimilar metals in an implant because of fear of inducing corrosion. There is a lack of systematic studies on the effects of mixing metals on performance of spinal implants, especially in fretting corrosion conditions. Hence, the goal was to determine whether mixing stainless steel (SS316L), titanium alloy (Ti6Al4V) and cobalt chromium (CoCrMo) alloy components in a spinal implant leads to any increased risk of corrosion degradation. Spinal constructs consisting of single assembly screw-connector-rod components were tested using a novel short-term cyclic fretting corrosion test method. A total of 17 alloy component combinations (comprised of SS316L, Ti6Al4V-anodized and CoCrMo alloy for rod, screws and connectors) were tested under three anatomic orientations. Spinal constructs having all SS316L were most susceptible to fretting-initiated crevice corrosion attack and showed higher average fretting currents (∼25 - 30 µA), whereas constructs containing all Ti6Al4V components were less susceptible to fretting corrosion with average fretting currents in the range of 1 - 6 µA. Mixed groups showed evidence of fretting corrosion but they were not as severe as all SS316L group. SEM results showed evidence of severe corrosion attack in constructs having SS316L components. There also did not appear to be any galvanic effects of combining alloys together. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1169-1177, 2017.
Topics: Alloys; Bone Screws; Corrosion; Humans; Implants, Experimental; Spine; Stainless Steel; Titanium; Vitallium
PubMed: 27038431
DOI: 10.1002/jbm.b.33661 -
Journal of Applied Biomaterials &... Jan 2018In this study, the super-long deep-hole drilling of a titanium alloy was investigated.
INTRODUCTION
In this study, the super-long deep-hole drilling of a titanium alloy was investigated.
METHODS
According to material properties of the titanium alloy, an experimental approach was designed to study three issues discovered during the drilling process: the hole-axis deflection, chip morphology, and tool wear.
RESULTS
Based on the results of drilling experiments, crucial parameters for the super-long deep-hole drilling of titanium alloys were obtained, and the influences of these parameters on quality of the alloy's machining were also evaluated.
CONCLUSIONS
Our results suggest that the developed drilling process is an effective method to overcome the challenge of super-long deep-hole drilling on difficult-to-cut materials.
Topics: Alloys; Titanium
PubMed: 29618262
DOI: 10.1177/2280800017751491