Biocompatibility Of Magnesium Alloys Research Articles

Термическая стабильность микроструктуры сплава MG-Y-ND в экструдированном состоянии

Introduction. Today, bioresorbable magnesium alloys possessing the required physical, mechanical, corrosion, and biological properties, are promising materials for orthopedic and cardiovascular surgery. The addition of rare earth elements such as yttrium, neodymium, and cerium to magnesium alloys improves its properties. Compared to widely used titanium alloys, magnesium alloys have a number of advantages. Bioresorbable materials slowly dissolve in the body, and recurrent operation to remove the implant is not needed. Biocompatible magnesium alloys have a fairly low elastic modulus (10 to 40 GPa), approaching to that of cortical bone, that reduces the contact stress in the bone-implant system. At the same time, strength properties of magnesium alloys alloyed with rare earth elements do not always meet the requirements for medical applications. Severe plastic deformation, for example, equal channel angular pressing, torsion under quasi-hydrostatic pressure, uniaxial forging, extrusion, is therefore very promising technique to gain the high level of mechanical properties of metals and alloys. Severe plastic deformation of magnesium alloys improves its structural strength by 2.5 times due to the generation of an ultrafine-grained and/or fine-grained structure. The issues related to the study of heat resistance, structure and phase composition of magnesium alloys with appropriate strength are relevant. Purpose of the work is to determine the influence of thermal effects on the microstructure of the extruded Mg-Y-Nd alloy. Methodology. The extruded Mg-2.9Y-1.3Nd alloy (95.0 wt. % Mg, 2.9 wt. % Y, 1.3 wt. % Nd,  0.2 wt. % Fe,  0 wt. % Al) is investigated in this paper. The thermal stability of the alloy microstructure is studied after annealing at 100, 300, 350, 450 and 525 °С in argon for one hour. The microstructure and phase composition are investigated using optical, transmission and scanning electron microscopes and analyzed on an X-ray diffractometer. Results and discussion. The extruded Mg-2.9Y-1.3Nd alloy has the bimodal fine-grained microstructure. It is found that along with the stable α-Mg phase, the alloy structure consists of Mg24Y5 intermetallic particles and -, -, and 1-phase precipitates. Annealing in the temperature range of 100–450 °С for one hour has no effect on the structure of the Mg-2.9Y-1.3Nd alloy, but promotes the growth in the linear dimensions of -, -, and 1-phases precipitates. In the temperature range of 300–450 °С, the morphology of -, ,- and 1-phases changes, while the average grain size of the major -phase remains unchanged. Annealing at 525 °С leads to a notable transformation of the bimodal microstructure of the alloy, which is associated with the intensive growth in the grain size of the -phase, Mg24Y5 particles, and -, -, and 1-phases precipitates. Annealing in the temperature range of 100–450 °C leads to an increase in the linear dimensions of Mg24Y5 particles, -, -, and 1-phases precipitates and bimodal microstructure of the Mg-2.9Y-1.3Nd alloy remains unchanged.

Study of in vitro wear resistance and degradation properties of self-made treated medical magnesium alloys

Study of <i>in vitro</i> wear resistance and degradation properties of self-made treated medical magnesium alloys

A polyphenol‐induced hydroxyapatite coating modulates corrosion resistance and biocompatibility of magnesium alloys

AbstractIn order to solve the problem of excessive degradation rate and insufficient biocompatibility of magnesium‐based bone implants, a polyphenol (EGCG) induced hydroxyapatite (HA) coating was prepared on the surface of AZ31 alloy. The physical and chemical properties and corrosion resistance of the coating were analysed in depth, and its biocompatibility was preliminarily explored in vitro. The results showed that the polyphenol (EGCG) conversion coating constructed on the AZ31 could successfully induce the formation of HA by complexing the phenolic hydroxyl group with calcium ions. The electrochemical and long‐term immersion experiments showed that the corrosion resistance of EGCG/HA composite coating was significantly improved. The self‐corrosion current density, hydrogen evolution and the increase of pH value of AZ31‐EGCG/HA were significantly lower than those of AZ31. On the basis of inhibiting the excessive corrosion of the substrate, the composite coating significantly improves the compatibility of pre‐osteoblasts, supports the adhesion and spreading and effectively reduces the haemolysis rate to less than 5%. The preparation method of the coating is simple, low cost and suitable for complex shape surfaces, which can significantly improve the corrosion resistance and biocompatibility of the AZ31 substrate. It is expected to provide a solution for the surface modification of magnesium‐based bone implants.

Strength enhancement and retention in magnesium subjected to uniaxial compression using centralized partial drill holes

The automotive industry approached light weighting vehicles using alloys and composites of aluminium and magnesium to improve fuel efficiency. They further introduced sensors to gain insight into real-time monitoring of their components. In the biomedical industry, reducing stiffness of implants, promoting cell proliferation, providing controlled drug delivery, and enabling real-time monitoring of implants has been the focus. With magnesium being a biocompatible material, research on improving the material properties of biocompatible magnesium alloys and composites is ongoing. However, tracking the efficiency of these implants in-vivo is essential and can be done using appropriate sensors. But the question of where to place them and would it affect the structural integrity of the implant needs to be answered. While previous research has explored the effect of through holes in different directions and materials, the effect of a controlled drill hole has not yet been explored. Hence, this study varies the drill depths in pure magnesium from 1 mm to 2.5 mm and drill diameter from 1 mm to 2.5 mm respectively in an 8 mm diameter cylinder to study the same. Further, an exploratory work on the effect of shape of the drill hole has also been taken up. Results convey that the sample with 1 mm drill diameter and 1.5 mm drill depth provided optimum results.

A chitosan/polylactic acid composite coating enhancing the corrosion resistance of the bio-degradable magnesium alloy

Magnesium alloy is a potential biodegradable material and is widely used in medicine. However, its rapid degradation causes many negative effects and limits its application, so it is essential to improve corrosion resistance. In this study, a chitosan/polylactic acid composite coating was designed on the AZ31 alloy for medical applications. The composite coating sealed the pores of the chitosan layer to provide strong protection for the AZ31 alloy, with a reduced corrosion current density by 4 orders of magnitude. The excellent biocompatibility of the composite coating was proved by an increased cell viability test and morphology of cells adhered to the chitosan/polylactic acid coated sample. The composite coating provides a feasible method to enhance the corrosion resistance and biocompatibility of magnesium alloys.

A calcium phosphate coating improving corrosion resistance of the biodegradable magnesium alloy with graphene oxide modifying the deposition

Biodegradable magnesium alloy is an ideal material for medical implant applications, but its application is limited by its rapid degradation. Therefore, it becomes the main goal to improve corrosion resistance. In this study, a calcium phosphate dihydrate/graphene oxide composite coating was designed on the AZ60 alloy for medical applications. A calcium phosphate dihydrate coating was first prepared by biomimetic deposition on the alkali pretreated magnesium alloy, and graphene oxide was dispersed in the solution to modify the deposition. The results showed that graphene oxide could not only alter the loose striped calcium phosphate coating to the compact flaked composite coating, but also enhance the corrosion resistance with a reduced corrosion current density by 2 orders of magnitude, an increased impedance by 3 orders of magnitude and a corrosion rate down to 7/20. The in vitro biocompatibility of the composite coating was also demonstrated by a series cell experiments, with a cell viability of 120%. The composite coating provides a feasible method to enhance the corrosion resistance and biocompatibility of magnesium alloys.

&lt;i&gt;In Vitro&lt;/i&gt; Corrosion Study of Selected Laser Melted WE43 Magnesium Alloy in Hank ́s Balanced Salt Solution

Magnesium (Mg) and its alloys have been intensively investigated as potential biocompatible materials with appropriate structural, mechanical and corrosion properties for preferable orthopedic applications. Selective Laser Melting (SLM) technique was developed for the fabrication of three-dimensional components with high structural integrity at a low cost and is compatible with various materials, including biocompatible magnesium alloys. In this study, WE43 magnesium alloy samples produced by SLM technique were examined by in vitro static test in Hank's balanced salt solution (HBSS) under physiological temperature conditions for six days. A hydrogen evolution method for the estimation of the corrosion rate was used. The phase composition of samples before and after the immersion test was investigated by X-ray diffraction (XRD). The surface morphology and chemical composition of the initial material and tested samples were characterized by scanning electron microscope (SEM) equipped with energy dispersive X-ray spectroscopy (EDX).

Modeling the Surface Integrity of Ball Burnished Biocompatible Magnesium Alloy by Soft Computing Techniques

Modeling the Surface Integrity of Ball Burnished Biocompatible Magnesium Alloy by Soft Computing Techniques

Improving the corrosion resistance and biocompatibility of magnesium alloy via composite coatings of calcium phosphate/carbonate induced by silane

Magnesium alloy is a potential biodegradable implant material, which has attracted wide attention because of its excellent mechanical properties, degradability and biocompatibility. However, its uncontrolled degradation and fast hydrogen gas production impede the clinical application. In order to solve this problem, we developed two composite coatings, the silane coupling agent-dicalcium phosphate dihydrate (SCA/DCPD) coating and the silane coupling agent‐‑calcium carbonate (SCA/CaCO3) coating. The morphology, composition, corrosion resistance and biocompatibility of the coated samples were systematically studied. The results showed that these two kinds of coatings could reduce the degradation of magnesium alloy, and have their own advantages. The SCA/DCPD coated sample showed better corrosion resistance, while the SCA/CaCO3 coated sample obtained better biocompatibility. Our research provided a novel sight and choice to design the biocompatibility coating and promote the clinical application for magnesium alloy.

Bilayer micro-arc oxidation-poly (glycerol sebacate) coating on AZ91 for improved corrosion resistance and biological activity

Magnesium alloys have recently been used in the biomedical field due to their low stress shielding and density closer to the natural bone. However, the corrosion resistance and biocompatibility of magnesium alloys should be improved for effective applications. In this study, a bilayer coating based on micro-arc oxidation and poly (glycerol sebacate) (PGS) (MAO-PGS) was developed on AZ91 alloy. Moreover, the effects of the electrosprying time (1, 3, 5 and 7 h) to develop PGS coatings on the physical, electrochemical and biological properties of the AZ91 alloy were evaluated. Electrochemical measurements in phosphate buffer solution confirmed that PGS coatings significantly improved the corrosion resistance of MAO coated sample, depending on the electrosprying time. Noticeably, by increasing PGS coating time upon 3 h, the corrosion resistance significantly improved, due to filling the pores formed during MAO process. Consequently, protein adsorption and biocompatibility of MAO-PGS coatings in contact with Human umbilical vein endothelial cells (HUVECs) significantly improved. Moreover, our result revealed the adhesion strength of MAO-PGS coating was directly modulated via PGS coating time. We found that 3 h coating significantly improved the adhesion strength of MAO coating. In summary, the bilayer MAO-PGS coatings on biodegradable AZ91 alloy not only increased corrosion resistance but also improved the biocompatibility of biodegradable AZ91 alloys. In summary, bilayer MAO-PGS coating may have the potential to provide greater protection of magnesium-based implants.

Construction of Chi(Zn/BMP2)/HA composite coating on AZ31B magnesium alloy surface to improve the corrosion resistance and biocompatibility

Abstract As biodegradable orthopedic implant materials, magnesium alloys have been attracted enough attentions recently. However, too fast degradation in vivo, limited biocompatibilities, and insufficient antibacterial properties are three main challenges at present. In order to solve these problems, a multifunctional composite coating of Chi(Zn/BMP2)/HA was constructed on AZ31B magnesium alloy surface, successively by the alkali heating treatment, self-assembly of 16-phosphonyl-hexadecanoic acid, in situ immobilization of Chi(Zn/BMP2) (chitosan, zinc ions, and bone morphogenetic protein 2), and the deposition of HA (hydroxyapatite). The results of ATR-FTIR (attenuated total reflection Fourier transform infrared spectrum) spectra and elemental compositions confirmed that 16-phosphonyl-hexadecanoic acid, Chi(Zn/BMP2), and HA were successfully immobilized on the surface. Compared with Mg, Mg-OH, Mg-16, and Mg-Chi(Zn/BMP2), Mg-Chi(Zn/BMP2)/HA with the concave–convex structure surface significantly enhanced the hydrophilicity and corrosion resistance. On the other hand, Mg-Chi(Zn/BMP2)/HA coating also showed excellent biocompatibilities, which not only significantly promoted the osteoblast adhesion and proliferation, but also upregulated ALP and OCN expression of osteoblasts. Furthermore, due to the synergistic antibacterial effect of zinc ions and chitosan, Mg-Chi(Zn/BMP2)/HA showed a good antibacterial property against Escherichia coli (E. coli). Therefore, it can be said that the method used in this work has a good application prospect in improving the corrosion resistance, biocompatibility of magnesium alloys, and inhibiting infections against E. coli.

THE EFFECT OF MULTIAXIAL DEFORMATION ON THE DYNAMICS OF BIODEGRADATION AND CELL COLONIZATION OF ALLOY WE43

Introduction. The development of materials for bioresorbable implants is an urgent issue in medicine and materials science. Magnesium alloys are promising materials for this purpose. In particular, alloy WE43 (Mg-Y-Nd-Zr) has proven itself well in this field. However, the use of magnesium alloys is limited by a high degradation rate, which is often accompanied with nonuniform corrosion, which negatively affects the load bearing capacity of the product. In addition, the increased degradation rate usually seriously worsens the biocompatibility of magnesium alloys. Therefore, the study of the corrosion resistance of magnesium alloys, as well astheir biocompatibility, is an urgent task.Purpose of the study was to investigate the effect of multiaxial deformation (MAD), aimed at increasing the mechanical characteristics of the alloy WE43, on its biodegradation kinetics, as well as on cell colonization.Materials and methods. The alloy WE43 in two states – homogenized (WE43 hom) and strengthened by MAD (WE43 MAD) was investigated in this work. The kinetics of biodegradation was investigated on an xCELLigence RTCA Systems analyzer. A method for estimating the volume of hydrogen was used to study the process of gas formation, which was recorded using an automated digital microscope LionheartTM FX. The corrosive medium was a solution based on Dulbecco’s Modified Eagle’s Medium. A culture of mesenchymal multipotent stromal cells was used to study the colonization of the alloy surface by cells.Results. MAD of the alloy WE43 leads to a decrease in the biodegradation rate and the intensity of gas formation. The period of stabilization of biodegradation for the alloy after the MAD is 16 hours versus 3 hours for the alloy after homogenization. In this case, the volume of released hydrogen was 65.0 ± 4.4 mm3H2/mm3 alloy and 211.0 ± ± 21.1 mm3H2/mm3 alloy for the alloy after MAD and homogenization, respectively. MAD improves the biocompatibility of the alloy WE43, stimulating the colonization of mesenchymal multipotent stromal cells.Conclusion. MAD reduces biodegradation and improves the biocompatibility of the alloy WE43, which makes it a promising medical material, including for the purposes of oncoorthopedics

Enhanced the corrosion resistance and biocompatibility of magnesium alloy by hydroxyapatite composite coating of AZ31/Ti/PDA/HA

A series of hydroxyapatite (HA) composite coatings of AZ31/HA, AZ31/PDA/HA, AZ31/Ti/HA, AZ31/Ti/PDA/HA were successfully fabricated combinedwith Ti ion implantation and Polydopamine (PDA). The SEM and EDS results showed that the AZ31/Ti/PDA/HA composite coating with a petal-like structure is more uniform and compact and the calcium-phosphorus ratio of AZ31/Ti/PDA/HA coating is 1.65, which is closer to the theoretical percentage of calcium-phosphorus in the hydroxyapatite of 1.67 compared to the other HA coatings. In addition, AZ31/Ti/PDA/HA coating exhibits best corrosion resistance, including the highest corrosion potential, lowest corrosion current and slowest amount of hydrogen evolution. The results of the MTT experiment showed that MC3T3-E1 cells presented a dendritic structure with no mitotic phase. The results of cell proliferation experiment showed that the cell proliferation rate of AZ31/PDA/HA, AZ31/Ti/HA, AZ31/Ti/PDA/HA group were higher than that of the negative control group except AZ31 substrate and AZ31/HA group. The 7-day cell proliferation rate of the AZ31/Ti/PDA/HA coating group was higher than those of the other groups. The AKP test showed that the ALP activity of the AZ31/Ti/PDA/HA coating group is strongest than other groups. Alizarin red staining results showed that the calcium nodules of the AZ31/Ti/PDA/HA coating group had the deepest staining and the highest density, which indicated that synergistic osteogenic ability of each component of composite coating was the best.

The effect of PEO parameters on the properties of biodegradable Mg alloys: a review

This paper comprehensively reviews recent research carried out in the field of preparation of bioactive coatings on magnesium (Mg)–aluminum (Al)–zinc (Zn) alloys by using the plasma electrolytic oxidation (PEO) method and investigation of factors affecting it. Magnesium–aluminum–zinc alloys (AZ grades) have been developed for use as biodegradation materials because the addition of aluminum and zinc as alloying elements can ameliorate their mechanical properties and increase corrosion resistance over those of pure magnesium alone without decrement in biocompatibility. Among the common methods for improvement of biodegradation, corrosion resistance and biocompatibility of magnesium alloys, surface modification techniques have been more effective. PEO is a relatively novel surface modification technique that provides excellent wear- and corrosion-resistant coatings on lightweight metals, in particular on magnesium and its alloys. The processing parameters of PEO, such as pulse frequencies, applied voltages, oxidation time, electrolyte concentrations and substrate chemical composition, are some of the major factors that determine the quality of the coatings in terms of corrosion resistance and bioactivity in body fluid solutions. Considering the fact that comprehensive review articles on the effect of PEO parameters on the properties of magnesium alloys have not been published in recent years, the aim of the present text is to provide an understanding of all aspects of these process parameters.

New approach for improving anticorrosion and biocompatibility of magnesium alloys via polydopamine intermediate layer-induced hydroxyapatite coating

Although magnesium alloys have become a promising candidate for bone implant materials, their rapid degradation has limited their use in medical applications. Surface modification is a feasible strategy for solving the corrosion problem of magnesium alloys. Here, we report a novel hydroxyapatite coating induced by polydopamine obtained using the hydrothermal treatment. The surface morphology and composition of the coating were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction. It was found that the dopamine-induced hydroxyapatite coating exhibits a more compact structure than the pure hydroxyapatite coating. Potentiodynamic polarization and simulated body fluid immersion tests demonstrated that the polydopamine-induced hydroxyapatite coating significantly reduced the corrosion rate due to the synergistic effect of the inner polydopamine layer and the outer hydroxyapatite coating. The cytocompatibility tests indicated that the composite coating significantly promoted the proliferation, adhesion and spread of osteoblasts. Thus, this coating may be a promising new approach for the surface modification of magnesium alloys.

Impact of a bioactive drug coating on the biocompatibility of magnesium alloys

Magnesium alloys are promising materials for biodegradable vascular stents because of their good biocompatibility and physical properties. The poly-β-hydroxybutyrate (PHB) coating with vascular endothelial growth factor and heparin was prepared on the surface of WE magnesium alloys by layer-by-layer self-assembly technique. In this study, the effects of magnesium alloys with bioactive drug coating on human umbilical vein endothelial cells (HUVECs) and blood compatibility were investigated. The results showed that magnesium alloys with bioactive drug coating could decrease platelet adhesion, platelet activation, hemolysis rate, fibrinogen adsorption and increase activated partial thromboplastin time, prothrombin time, dynamic clotting of magnesium alloys. In addition, magnesium alloys with bioactive drug coating did not alter cytoskeleton morphological features of HUVECs, promoted cell adhesion and cell growth, and inhibited cell apoptosis. Therefore, the magnesium alloys with bioactive drug coating can be considered as potential and degradable biomaterials for vascular stents.

Enhanced corrosion resistance and biocompatibility of magnesium alloy by hydroxyapatite/graphene oxide bilayer coating

Fast degradation is the major limitation for biomedical application of Mg alloy. In the current work, a bilayer coating (HA/GO#) with hydroxyapatite as the inner layer and graphene oxide as the out layer was prepared on AZ31 alloy. Graphene oxide could sufficiently inhibit the formation and growth of corrosion cracks on hydroxyapatite layer, which result in its superior corrosion resistance. In vitro cell viability results suggested that MC3T3-E1 cells exhibited larger spreading area on HA/GO# coating at the initial 4 h of incubation. Furthermore, cells on HA/GO# coating showed superior proliferation rate. Considering its satisfied corrosion resistance and biocompatibility, the as prepared bilayer coating on AZ31 alloy is promising for clinical application.

The Effect of Laser Shock Peening on the Corrosion Behavior of Biocompatible Magnesium Alloy ZK60

The influences of different laser power density in LSP (laser shock peening) on the corrosion performance of biocompatible magnesium alloy ZK60 were researched via SBF (Simulated Body Fliud) immersion testing and electrochemical testing. Corrosion morphology and corrosion products were observed and analyzed using SEM (Scanning Electron Microscope) outfitted with EDS (Energy Dispersive Spectrometer) and XRD (X-ray Diffraction). Simultaneously, 3D morphology, surface roughness, residual stress, and microstructure were also characterized. Results reveal that the modified samples can obtain higher residual compressive stress, which can lead to lower degradation rates in SBF solution. In terms of the weight loss of the samples, corrosion resistance increased by 52.1% maximally. The corrosion potential of modified samples in the SBF solution positively shifted from −1.3884 V to −1.1094 V and the corrosion current density decreased by 13.2% at most. The anti-corrosion ability of ZK60 is significantly enhanced by the LSP process.

One-Pot but Two-Step Vapor-Based Amine- and Fluorine-Bearing Dual-Layer Coating for Improving Anticorrosion and Biocompatibility of Magnesium Alloy.

Hydrophobic coating is of great interest to enhance the corrosion resistance of magnesium alloy implants, which always suffer from rapid corrosion that leads to the failing application under physiological conditions. Plasma-polymerized fluorocarbon (C-F) coating has been widely studied as a substrate protection layer; however, the precise control of the deposition rate of C-F coating with fluorinated alkanes has been a challenge. In this study, a thin, uniform, pinhole-free, polymerlike, and hydrophobic C-F coating was successfully prepared using acetylene (C2H2) as a cross-linking agent, which endows the coating with tunable properties of deposition rate by incorporation of unsaturated bonds. Electrochemical corrosion and in vitro immersion test demonstrated that the C-F coating significantly slows down the corrosion rate of MgZnMn in phosphate-buffered saline solution at 37 °C. Furthermore, an additional layer of PPAam was deposited on the C-F coating to eliminate the adverse effect of C-F surface on cytocompatibility. Thus, such a stacked coating imparts MgZnMn with a significantly improved corrosion resistance and promotes cell adhesion and viability. Therefore, the strategy of acetylene-mediated C-F-based coating shows a great potential for tailoring ideal surface functionalities of magnesium-based medical devices.

Fabrication of chitosan/heparinized graphene oxide multilayer coating to improve corrosion resistance and biocompatibility of magnesium alloys.

Due to its good biodegradability and mechanical properties, magnesium alloys are considered as the ideal candidate for the cardiovascular stents. However, the rapid degradation in human physiological environment and the poor biocompatibility seriously limit its application for biomaterials. In the present study, a chitosan/heparinized graphene oxide (Chi/HGO) multilayer coating was constructed on the AZ31B magnesium alloy surface using layer-by-layer (LBL) method to improve the corrosion resistance and biocompatibility. The results of attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), Raman spectrum (RAMAN), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) showed that a dense and compact Chi/HGO multilayer coating was fabricated on the magnesium alloy surface. The results of potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), pH value changes and magnesium ion release suggested that the multilayer coating can significantly enhance the corrosion resistance of the magnesium alloy. Moreover, the Chi/HGO multilayer coating could not only significantly reduce the hemolysis rate and platelet adhesion, but also promote the adhesion and proliferation of endothelial cells. Therefore, the Chi/HGO multilayer coating can simultaneously improve the corrosion resistance and biocompatibility of the magnesium alloys.