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4 pages, 173 KiB

Open AccessEditorial

Development and Application of Biodegradable Metals

by Petra Maier

Metals 2022, 12(8), 1312; https://doi.org/10.3390/met12081312 - 5 Aug 2022

Viewed by 1276

Abstract

Magnesium-, zinc- and iron-based alloys as biodegradable metals have been a focus of scientific attention for their ability to eliminate the need for a second surgery in order to remove implants made with such materials [...] Full article

(This article belongs to the Special Issue Development and Application of Biodegradable Metals)

Research

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13 pages, 1909 KiB

Open AccessArticle

Effect of Milling Parameters on Mechanical Properties and In Vitro Biocompatibility of Mg-Zn-Co Ternary Alloy

by Sehrish Mukhtar, Muhammad Kamran, Rafiq Ahmed and Asima Tayyeb

Metals 2022, 12(3), 529; https://doi.org/10.3390/met12030529 - 21 Mar 2022

Cited by 2 | Viewed by 1894

Abstract

Magnesium (Mg) is a potential candidate for biomedical implants, but its susceptibility to suffer corrosion attack in human body fluid limits its practical use. Thus, alloying Mg with other metal elements is the most effective strategy to improve its mechanical properties and biocompatibility. [...] Read more.

Magnesium (Mg) is a potential candidate for biomedical implants, but its susceptibility to suffer corrosion attack in human body fluid limits its practical use. Thus, alloying Mg with other metal elements is the most effective strategy to improve its mechanical properties and biocompatibility. Herein, we report a Mg-Zn-Co ternary alloy (85-10-5 wt %) synthesized by the mechanical alloying technique. Ball-milling parameters such as ball size and milling time were varied to obtain better alloy properties. After compaction and sintering, the obtained alloy samples were subjected to various characterizations, including grain, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy, X-ray diffraction (XRD), microhardness and nanoindentation analyses. In vitro biocompatibility analysis of different alloys was also performed with MC3T3-E1 osteoblasts. Grain analysis confirmed the even dispersion of particles, while SEM analysis showed the formation of laminates, spherical and fine particles with an increase in time and varied ball size. XRD results further confirmed the formation of intermetallic compounds. The microhardness of samples was increased with the increase in milling time. The Young’s modulus of ternary alloys obtained from nanoindentation analysis was comparable to the modulus of human bone. Moreover, in vitro analysis with osteoblasts showed that the developed alloys were noncytotoxic and biocompatible. Full article

(This article belongs to the Special Issue Development and Application of Biodegradable Metals)

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16 pages, 7066 KiB

Open AccessArticle

The Effect of Co-Encapsulated GO-Cu Nanofillers on Mechanical Properties, Cell Response, and Antibacterial Activities of Mg-Zn Composite

by Abbas Saberi, Hamid Reza Bakhsheshi-Rad, Ahmad Fauzi Ismail, Safian Sharif, Mahmood Razzaghi, Seeram Ramakrishna and Filippo Berto

Metals 2022, 12(2), 207; https://doi.org/10.3390/met12020207 - 22 Jan 2022

Cited by 15 | Viewed by 2910

Abstract

Magnesium-based composites have recently been studied as biodegradable materials for preparing orthopedic implants. In this article, the graphene oxide (GO) and GO-Cu nanosystem has been homogenously dispersed as a reinforcement in the matrix of Mg-Zn (MZ) alloy using the semi powder metallurgy (SPM) [...] Read more.

Magnesium-based composites have recently been studied as biodegradable materials for preparing orthopedic implants. In this article, the graphene oxide (GO) and GO-Cu nanosystem has been homogenously dispersed as a reinforcement in the matrix of Mg-Zn (MZ) alloy using the semi powder metallurgy (SPM) method, and subsequently, the composite has been successfully manufactured using the spark plasma sintering (SPS) process. GO and GO-Cu reinforced composite displayed a higher compressive strength (~55%) than the unreinforced Mg-Zn sample. GO and GO-Cu dual nanofillers presented a synergistic effect on enhancing the effectiveness of load transfer and crack deflection in the Mg-based matrix. Besides, the GO-Cu dual nanofillers displayed a synergistic influence on antibacterial activity through combining the capturing influences of GO nanosheets with the killing influences of Cu. However, electrochemical and in-vitro immersion evaluation showed that Cu-GO reinforcement had a slightly negative effect on the corrosion behavior of the Mg-Zn sample, but the incorporation of GO enhanced corrosion resistance of the composite. Moreover, MZ/GO and MZ/GO-Cu nanocomposites showed acceptable cytotoxicity to MG-63 cells and revealed a high potential for use as an orthopedic implant material. Based on the research results, MZ/GO-Cu nanocomposite could be used in bone tissue engineering applications. Full article

(This article belongs to the Special Issue Development and Application of Biodegradable Metals)

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14 pages, 6080 KiB

Open AccessArticle

Mechanical Alloying Process Applied for Obtaining a New Biodegradable Mg-xZn-Zr-Ca Alloy

by Doina Raducanu, Vasile Danut Cojocaru, Anna Nocivin, Radu Hendea, Steliana Ivanescu, Doina Stanciu, Corneliu Trisca-Rusu, Silviu Iulian Drob and Elisabeta Mirela Cojocaru

Metals 2022, 12(1), 132; https://doi.org/10.3390/met12010132 - 11 Jan 2022

Cited by 6 | Viewed by 2169

Abstract

The aim of the present paper is to apply the mechanical alloying process to obtain from powder components a new biodegradable Mg-based alloy powder from the system Mg-xZn-Zr-Ca, with high biomechanical and biochemical performance. Various processing parameters for mechanical alloying have been experimented [...] Read more.

The aim of the present paper is to apply the mechanical alloying process to obtain from powder components a new biodegradable Mg-based alloy powder from the system Mg-xZn-Zr-Ca, with high biomechanical and biochemical performance. Various processing parameters for mechanical alloying have been experimented with the ultimate goal to establish an efficient processing route for the production of small biodegradable parts for the medical domain. It has been observed that for the same milling parameters, the composition of the powders has influenced the powder size and shape. On the other hand, for the same composition, the highest experimented milling speed and time conduct to finer powder particles, almost round-shaped, without pores or various inclusions. The most uniform size has been obtained for the powder sample with 10 wt.%Zn. These powders were finally processed by selective laser melting, an additive manufacturing technology, to obtain a homogeneous experimental sample, without cracking, for future more systematical trials. Full article

(This article belongs to the Special Issue Development and Application of Biodegradable Metals)

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11 pages, 1383 KiB

Open AccessArticle

Mechanical Behavior and In Vitro Corrosion of Cubic Scaffolds of Pure Magnesium Processed by Severe Plastic Deformation

by Claudio L. P. Silva, Marcelo A. Camara, Anton Hohenwarter and Roberto B. Figueiredo

Metals 2021, 11(11), 1791; https://doi.org/10.3390/met11111791 - 8 Nov 2021

Cited by 9 | Viewed by 1792

Abstract

Reports in the literature show that severe plastic deformation can improve mechanical strength, ductility, and corrosion resistance of pure magnesium, which suggests good performance for biodegradable applications. However, the reported results were based on testing of small samples on limited directions. The present [...] Read more.

Reports in the literature show that severe plastic deformation can improve mechanical strength, ductility, and corrosion resistance of pure magnesium, which suggests good performance for biodegradable applications. However, the reported results were based on testing of small samples on limited directions. The present study reports compression testing of larger samples, at different directions, in pure magnesium processed by hot rolling, equal channel angular pressing (ECAP), and high pressure torsion (HPT). The results show that severe plastic deformation through ECAP and HPT reduces anisotropy and increases strength and strain rate sensitivity. Also, scaffolds were fabricated from the material with different processing histories and immersed in Hank’s solution for up to 14 days. The as-cast material displays higher corrosion rate and localized corrosion and it is reported that severe plastic deformation induces uniform corrosion and reduces the corrosion rate. Full article

(This article belongs to the Special Issue Development and Application of Biodegradable Metals)

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12 pages, 8464 KiB

Open AccessFeature PaperArticle

Degradation Analysis of Thin Mg-xAg Wires Using X-ray Near-Field Holotomography

by Sebastian Meyer, Andreas Wolf, Daniela Sanders, Kamila Iskhakova, Hanna Ćwieka, Stefan Bruns, Silja Flenner, Imke Greving, Johannes Hagemann, Regine Willumeit-Römer, Björn Wiese and Berit Zeller-Plumhoff

Metals 2021, 11(9), 1422; https://doi.org/10.3390/met11091422 - 8 Sep 2021

Cited by 11 | Viewed by 2653

Abstract

Magnesium–silver alloys are of high interest for the use as temporary bone implants due to their antibacterial properties in addition to biocompatibility and biodegradability. Thin wires in particular can be used for scaffolding, but the determination of their degradation rate and homogeneity using [...] Read more.

Magnesium–silver alloys are of high interest for the use as temporary bone implants due to their antibacterial properties in addition to biocompatibility and biodegradability. Thin wires in particular can be used for scaffolding, but the determination of their degradation rate and homogeneity using traditional methods is difficult. Therefore, we have employed 3D imaging using X-ray near-field holotomography with sub-micrometer resolution to study the degradation of thin (250 μm diameter) Mg-2Ag and Mg-6Ag wires. The wires were studied in two states, recrystallized and solution annealed to assess the influence of Ag content and precipitates on the degradation. Imaging was employed after degradation in Dulbecco’s modified Eagle’s medium and 10% fetal bovine serum after 1 to 7 days. At 3 days of immersion the degradation rates of both alloys in both states were similar, but at 7 days higher silver content and solution annealing lead to decreased degradation rates. The opposite was observed for the pitting factor. Overall, the standard deviation of the determined parameters was high, owing to the relatively small field of view during imaging and high degradation inhomogeneity of the samples. Nevertheless, Mg-6Ag in the solution annealed state emerges as a potential material for thin wire manufacturing for implants. Full article

(This article belongs to the Special Issue Development and Application of Biodegradable Metals)

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11 pages, 28185 KiB

Open AccessFeature PaperArticle

Influence of Cooling Conditions on Long-Period Stacking-Ordered Phase Evolution and Corrosion Behavior of As-Cast Resoloy^®

by Sandra Ahlers, Benjamin Bittner and Petra Maier

Metals 2021, 11(9), 1372; https://doi.org/10.3390/met11091372 - 30 Aug 2021

Cited by 3 | Viewed by 1625

Abstract

This study focuses on the influence of cooling conditions on the long-period stacking-ordered (LPSO) phase evolution and corrosion behavior of as-cast Resoloy^®, a bioresorbable Mg-Dy-based alloy. Metallographic and corrosive tests are used to monitor the changes in the properties of this [...] Read more.

This study focuses on the influence of cooling conditions on the long-period stacking-ordered (LPSO) phase evolution and corrosion behavior of as-cast Resoloy^®, a bioresorbable Mg-Dy-based alloy. Metallographic and corrosive tests are used to monitor the changes in the properties of this material. The corrosion behavior is investigated by potentiodynamic polarisation. Permanent mold chill casted ingots are wire-eroded to cylindrical platelets. The eroded platelets are solution heat treated over three different time periods. Cooling is performed in two different ways: quenching in water and cooling in air at ambient temperature. The as-cast condition shows a homogeneous fine-grained microstructure. Grains become larger with increasing heat treatment duration and slow cooling leads to additional grain growth. Furthermore, cooling in air leads to faint lamellar LPSO structures, which develop from bulk LPSO structures during the cooling process. The corrosion rate of the cooled platelets increases with increasing grain size. When the lamellar LPSO structures are uniformly distributed over the entire grain, the corrosion starts at the matrix between the LPSO lamellae and stops at them. Heat treatment at 500 °C reduces the normal potential difference between matrix and secondary phase and thus weakens the galvanic corrosion. Full article

(This article belongs to the Special Issue Development and Application of Biodegradable Metals)

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16 pages, 3535 KiB

Open AccessArticle

Antimicrobial Activity and Degradation of Superhydrophobic Magnesium Substrates in Bacterial Media

by Alexandre M. Emelyanenko, Valery V. Kaminsky, Ivan S. Pytskii, Kirill A. Emelyanenko, Alexander G. Domantovsky, Elizaveta V. Chulkova, Andrei A. Shiryaev, Andrei V. Aleshkin and Ludmila B. Boinovich

Metals 2021, 11(7), 1100; https://doi.org/10.3390/met11071100 - 10 Jul 2021

Cited by 10 | Viewed by 2009

Abstract

The interest in magnesium-based materials is promoted by their biocompatibility, their bioresorbability, and their recently discovered antibacterial potential. Until now, the widespread use of magnesium alloys in different corrosive environments was inhibited by their weakly controllable degradation rate and poorly understood microbiologically induced [...] Read more.

The interest in magnesium-based materials is promoted by their biocompatibility, their bioresorbability, and their recently discovered antibacterial potential. Until now, the widespread use of magnesium alloys in different corrosive environments was inhibited by their weakly controllable degradation rate and poorly understood microbiologically induced corrosion behavior. To better understand the degradation and usability of magnesium-based alloys, in this study we have fabricated superhydrophobic coatings on a magnesium-based alloy, and analyzed the behavior of this alloy in bacterial dispersions of Pseudomonas aeruginosa and Klebsiella pneumoniae cells in phosphate-buffered saline. It was shown that the immersion of such coatings in bacterial dispersions causes notable changes in the morphology of the samples, dependent on the bacterial dispersion composition and the type of bacterial strain. The interaction of the superhydrophobic coatings with the bacterial dispersion caused the formation of biofilms and sodium polyphosphate films, which provided enhanced barrier properties in magnesium dissolution and hence in dispersion medium alkalization, eventually leading to the inhibition of magnesium substrate degradation. The electrochemical data obtained for superhydrophobic samples in continuous contact with corrosive bacterial dispersions for 48 h indicated a high level of anticorrosion protection. Full article

(This article belongs to the Special Issue Development and Application of Biodegradable Metals)

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16 pages, 5088 KiB

Open AccessEditor’s ChoiceArticle

In Vitro Degradation Behavior and Biocompatibility of Bioresorbable Molybdenum

by Christian Redlich, Antje Schauer, Jakob Scheibler, Georg Poehle, Peggy Barthel, Anita Maennel, Volker Adams, Thomas Weissgaerber, Axel Linke and Peter Quadbeck

Metals 2021, 11(5), 761; https://doi.org/10.3390/met11050761 - 5 May 2021

Cited by 17 | Viewed by 3314

Abstract

The degradation behavior and biocompatibility of pure molybdenum (Mo) were investigated. Dissolution of powder metallurgically manufactured and commercially available Mo was investigated by ion concentration measurement after immersion in modified Kokubo’s SBF (c-SBF-Ca) for 28 days at 37 °C and pH 7.4. Degradation [...] Read more.

The degradation behavior and biocompatibility of pure molybdenum (Mo) were investigated. Dissolution of powder metallurgically manufactured and commercially available Mo was investigated by ion concentration measurement after immersion in modified Kokubo’s SBF (c-SBF-Ca) for 28 days at 37 °C and pH 7.4. Degradation layers and corrosion attack were examined with optical microscopy and REM/EDX analysis. Furthermore, potentiodynamic polarization measurements were conducted. Mo gradually dissolves in modified SBF releasing molybdate anions (MoO₄²⁻). The dissolution rate after 28 days is 10 µm/y for both materials and dissolution accelerates over time. A non-passivating, uniform and slowly soluble degradation product layer is observed. Additionally, apoptosis and necrosis assays with Mo ion extracts and colonization tests with human endothelial (HCAEC) and smooth muscle cell lines (HCASMC) on Mo substrates were performed. No adverse effects on cell viability were observed for concentrations expected from the dissolution of implants with typical geometries and substrates were densely colonized by both cell lines. Furthermore, Mo does not trigger thrombogenic or inflammatory responses. In combination with its favorable mechanical properties and the renal excretion of bio-available molybdate ions, Mo may be an alternative to established bioresorbable metals. Full article

(This article belongs to the Special Issue Development and Application of Biodegradable Metals)

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