Special Issue "Biodegradable Metals"

A special issue of Metals (ISSN 2075-4701).

Deadline for manuscript submissions: 31 January 2018

Special Issue Editor

Guest Editor
Prof. Dr. Eli Aghion

Department of Materials Engineering, Ben-Gurion University of the Negev, Beer Sheva, Israel
Website | E-Mail

Special Issue Information

Dear Colleagues,

The interest in biocompatible and biodegradable metals, such as magnesium, is mainly related to their potential use as structural material for orthopedic and cardiovascular applications where a temporary medical device is required. However, in the case of magnesium, in vivo experiments have clearly shown that the corrosion degradation rate of magnesium and its alloys is too high and, hence, results in producing gas cavities that can promote the danger of gas embolism, tissue separation, and premature loss of mechanical integrity. The aim of this Special Issue on Biodegradable Metals is to explore and introduce innovative strategies to overcome the current limitations of magnesium. Papers relating to other potential biodegradable metals, such as Iron and Zinc, are also welcome.

Prof. Dr. Eli Aghion
Guest Editor

Manuscript Submission Information

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Keywords

  • Magnesium
  • Iron
  • Zinc
  • Biomaterials
  • Implants
  • Biocompatibility
  • Biodegradable
  • Bioabsorble
  • Biocorrosion

Published Papers (7 papers)

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Research

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Open AccessArticle Development of a Novel Degradation-Controlled Magnesium-Based Regeneration Membrane for Future Guided Bone Regeneration (GBR) Therapy
Metals 2017, 7(11), 481; doi:10.3390/met7110481
Received: 21 September 2017 / Revised: 27 October 2017 / Accepted: 3 November 2017 / Published: 6 November 2017
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Abstract
This study aimed to develop and evaluate the ECO-friendly Mg-5Zn-0.5Zr (ECO505) alloy for application in dental-guided bone regeneration (GBR). The microstructure and surface properties of biomedical Mg materials greatly influence anti-corrosion performance and biocompatibility. Accordingly, for the purpose of microstructure and surface modification,
[...] Read more.
This study aimed to develop and evaluate the ECO-friendly Mg-5Zn-0.5Zr (ECO505) alloy for application in dental-guided bone regeneration (GBR). The microstructure and surface properties of biomedical Mg materials greatly influence anti-corrosion performance and biocompatibility. Accordingly, for the purpose of microstructure and surface modification, heat treatments and surface coatings were chosen to provide varied functional characteristics. We developed and integrated both an optimized solution heat-treatment condition and surface fluoride coating technique to fabricate a Mg-based regeneration membrane. The heat-treated Mg regeneration membrane (ARRm-H380) and duplex-treated regeneration membrane group (ARRm-H380-F24 h) were thoroughly investigated to characterize the mechanical properties, as well as the in vitro corrosion and in vivo degradation behaviors. Significant enhancement in ductility and corrosion resistance for the ARRm-H380 was obtained through the optimized solid-solution heat treatment; meanwhile, the corrosion resistance of ARRm-H380-F24 h showed further improvement, resulting in superior substrate integrity. In addition, the ARRm-H380 provided the proper amount of Mg-ion concentration to accelerate bone growth in the early stage (more than 80% new bone formation). From a specific biomedical application point of view, these research results point out a successful manufacturing route and suggest that the heat treatment and duplex treatment could be employed to offer custom functional regeneration membranes for different clinical patients. Full article
(This article belongs to the Special Issue Biodegradable Metals)
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Open AccessArticle Influence of the Composition of the Hank’s Balanced Salt Solution on the Corrosion Behavior of AZ31 and AZ61 Magnesium Alloys
Metals 2017, 7(11), 465; doi:10.3390/met7110465
Received: 31 August 2017 / Revised: 23 October 2017 / Accepted: 25 October 2017 / Published: 1 November 2017
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Abstract
The electrochemical corrosion characteristics of AZ31 and AZ61 magnesium alloys were analyzed in terms of potentiodynamic tests and electrochemical impedance spectroscopy. The influence of the solution composition and material surface finish was examined also through the analysis of corrosion products created on the
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The electrochemical corrosion characteristics of AZ31 and AZ61 magnesium alloys were analyzed in terms of potentiodynamic tests and electrochemical impedance spectroscopy. The influence of the solution composition and material surface finish was examined also through the analysis of corrosion products created on the samples’ surface after electrochemical measurements in terms of scanning electron microscopy using energy-dispersive spectroscopy. Obtained data revealed the differences in the response of the magnesium alloys to enriched Hank’s Balanced Salt Solution—HBSS+ (with Mg2+ and Ca2+ ions) and Hank’s Balanced Salt Solution—HBSS (without Mg2+ and Ca2+ ions). Both examined alloys exhibited better corrosion resistance from the thermodynamic and kinetic point of view in the enriched HBSS+. AZ61 magnesium alloy reached higher values of polarization resistance than AZ31 magnesium alloy in both the used corrosion solutions. Phosphate-based corrosion products were characteristic for the AZ31 and AZ61 alloys tested in the HBSS (without Mg2+ and Ca2+ ions). The combination of phosphate-based corrosion products and clusters of MgO and Mg(OH)2 was typical for the surface of samples tested in the enriched HBSS+ (with Mg2+ and Ca2+ ions). Pitting corrosion attack was observed only in the case of enriched HBSS+. Full article
(This article belongs to the Special Issue Biodegradable Metals)
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Open AccessArticle Characterization of Powder Metallurgy Processed Pure Magnesium Materials for Biomedical Applications
Metals 2017, 7(11), 461; doi:10.3390/met7110461
Received: 14 September 2017 / Revised: 23 October 2017 / Accepted: 24 October 2017 / Published: 31 October 2017
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Abstract
Magnesium with its mechanical properties and nontoxicity is predetermined as a material for biomedical applications; however, its high reactivity is a limiting factor for its usage. Powder metallurgy is one of the promising methods for the enhancement of material mechanical properties and, due
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Magnesium with its mechanical properties and nontoxicity is predetermined as a material for biomedical applications; however, its high reactivity is a limiting factor for its usage. Powder metallurgy is one of the promising methods for the enhancement of material mechanical properties and, due to the introduced plastic deformation, can also have a positive influence on corrosion resistance. Pure magnesium samples were prepared via powder metallurgy. Compacting pressures from 100 MPa to 500 MPa were used for samples’ preparation at room temperature and elevated temperatures. The microstructure of the obtained compacts was analyzed in terms of microscopy. The three-point bendisng test and microhardness testing were adopted to define the compacts’ mechanical properties, discussing the results with respect to fractographic analysis. Electrochemical corrosion properties analyzed with electrochemical impedance spectroscopy carried out in HBSS (Hank’s Balanced Salt Solution) and enriched HBSS were correlated with the metallographic analysis of the corrosion process. Cold compacted materials were very brittle with low strength (up to 50 MPa) and microhardness (up to 50 HV (load: 0.025 kg)) and degraded rapidly in both solutions. Hot pressed materials yielded much higher strength (up to 250 MPa) and microhardness (up to 65 HV (load: 0.025 kg)), and the electrochemical characteristics were significantly better when compared to the cold compacted samples. Temperatures of 300 °C and 400 °C and high compacting pressures from 300 MPa to 500 MPa had a positive influence on material bonding, mechanical and electrochemical properties. A compacting temperature of 500 °C had a detrimental effect on material compaction when using pressure above 200 MPa. Full article
(This article belongs to the Special Issue Biodegradable Metals)
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Open AccessArticle Preparation and Characterization of Zinc Materials Prepared by Powder Metallurgy
Metals 2017, 7(10), 396; doi:10.3390/met7100396
Received: 30 August 2017 / Revised: 18 September 2017 / Accepted: 22 September 2017 / Published: 27 September 2017
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Abstract
The use of zinc-based materials as biodegradable materials for medical purposes is offered as a possible alternative to corrosion-less resistant magnesium-based materials. Zinc powders with two different particle sizes (7.5 µm and 150 µm) were processed by the methods of powder metallurgy: cold
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The use of zinc-based materials as biodegradable materials for medical purposes is offered as a possible alternative to corrosion-less resistant magnesium-based materials. Zinc powders with two different particle sizes (7.5 µm and 150 µm) were processed by the methods of powder metallurgy: cold pressing, cold pressing followed by sintering and hot pressing. The microstructure of prepared materials was evaluated in terms of light optical microscopy, and the mechanical properties were analyzed with Vickers microhardness testing and three-point bend testing. Fractographic analysis of broken samples was performed with scanning electron microscopy. Particle size was shown to have a significant effect on compacts mechanical properties. The deformability of 7.5 µm particle size powder was improved by increased temperature during the processing, while in the case of larger powder, no significant influence of temperature was observed. Bending properties of prepared materials were positively influenced by elevated temperature during processing and correspond to the increasing compacting pressures. Better properties were achieved for pure zinc prepared from 150 µm particle size powder compared to materials prepared from 7.5 µm particle size powder. Full article
(This article belongs to the Special Issue Biodegradable Metals)
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Open AccessFeature PaperArticle Investigation on Mechanical Behavior of Biodegradable Iron Foams under Different Compression Test Conditions
Metals 2017, 7(6), 202; doi:10.3390/met7060202
Received: 13 April 2017 / Revised: 25 May 2017 / Accepted: 30 May 2017 / Published: 2 June 2017
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Abstract
Biodegradable metal foams have been studied as potential materials for bone scaffolds. Their mechanical properties largely depend on the relative density and micro-structural geometry. In this work, mechanical behavior of iron foams with different cell sizes was investigated under various compression tests in
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Biodegradable metal foams have been studied as potential materials for bone scaffolds. Their mechanical properties largely depend on the relative density and micro-structural geometry. In this work, mechanical behavior of iron foams with different cell sizes was investigated under various compression tests in dry and wet conditions and after subjected to degradation in Hanks’ solution. Statistical analysis was performed using hypothesis and non-parametric tests. The deformation behavior of the foams under compression was also evaluated. Results show that the mechanical properties of the foams under dry compression tests had a “V-type” variation, which is explained as a function of different geometrical properties by using a simple tabular method. The wet environment did not change the compression behavior of the iron foams significantly while degradation decreased the elastic modulus, yield and compression strengths and the energy absorbability of the specimens. The deformation of open cell iron foams under compression is viewed as a complex phenomenon which could be the product of multiple mechanism such as bending, buckling and torsion. Full article
(This article belongs to the Special Issue Biodegradable Metals)
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Review

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Open AccessFeature PaperReview The Biological Responses to Magnesium-Based Biodegradable Medical Devices
Metals 2017, 7(11), 514; doi:10.3390/met7110514
Received: 20 September 2017 / Revised: 16 November 2017 / Accepted: 18 November 2017 / Published: 21 November 2017
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Abstract
The biocompatibility of Magnesium-based materials (MBMs) is critical to the safety of biodegradable medical devices. As a promising metallic biomaterial for medical devices, the issue of greatest concern is devices’ safety as degrading products are possibly interacting with local tissue during complete degradation.
[...] Read more.
The biocompatibility of Magnesium-based materials (MBMs) is critical to the safety of biodegradable medical devices. As a promising metallic biomaterial for medical devices, the issue of greatest concern is devices’ safety as degrading products are possibly interacting with local tissue during complete degradation. The aim of this review is to summarize the biological responses to MBMs at the cellular/molecular level, including cell adhesion, transportation signaling, immune response, and tissue growth during the complex degradation process. We review the influence of MBMs on gene/protein biosynthesis and expression at the site of implantation, as well as throughout the body. This paper provides a systematic review of the cellular/molecular behavior of local tissue on the response to Mg degradation, which may facilitate a better prediction of long-term degradation and the safe use of magnesium-based implants through metal innovation. Full article
(This article belongs to the Special Issue Biodegradable Metals)
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Open AccessReview The Prospects of Zinc as a Structural Material for Biodegradable Implants—A Review Paper
Metals 2017, 7(10), 402; doi:10.3390/met7100402
Received: 31 August 2017 / Revised: 21 September 2017 / Accepted: 22 September 2017 / Published: 1 October 2017
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Abstract
In the last decade, iron and magnesium, both pure and alloyed, have been extensively studied as potential biodegradable metals for medical applications. However, broad experience with these material systems has uncovered critical limitations in terms of their suitability for clinical applications. Recently, zinc
[...] Read more.
In the last decade, iron and magnesium, both pure and alloyed, have been extensively studied as potential biodegradable metals for medical applications. However, broad experience with these material systems has uncovered critical limitations in terms of their suitability for clinical applications. Recently, zinc and zinc-based alloys have been proposed as new additions to the list of degradable metals and as promising alternatives to magnesium and iron. The main byproduct of zinc metal corrosion, Zn2+, is highly regulated within physiological systems and plays a critical role in numerous fundamental cellular processes. Zn2+ released from an implant may suppress harmful smooth muscle cells and restenosis in arteries, while stimulating beneficial osteogenesis in bone. An important limitation of pure zinc as a potential biodegradable structural support, however, lies in its low strength (σUTS ~ 30 MPa) and plasticity (ε < 0.25%) that are insufficient for most medical device applications. Developing high strength and ductility zinc with sufficient hardness, while retaining its biocompatibility, is one of the main goals of metallurgical engineering. This paper will review and compare the biocompatibility, corrosion behavior and mechanical properties of pure zinc, as well as currently researched zinc alloys. Full article
(This article belongs to the Special Issue Biodegradable Metals)
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