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Materials Science & Engineering. C,... Jul 2021In order to prepare a titanium with a low elastic modulus and good antibacterial property to meet the requirements as a biomedical material, Ti-13Nb-13Zr-5Cu (TNZ-5Cu)...
In order to prepare a titanium with a low elastic modulus and good antibacterial property to meet the requirements as a biomedical material, Ti-13Nb-13Zr-5Cu (TNZ-5Cu) alloy was prepared by high vacuum consume electric arc melting furnace and then subjected to a solution treatment at 950 °C followed by a short-term aging treatment at 600 °C, for 15 min, 30 min, 1 h and 2 h, respectively. The microstructure, mechanical property, antibacterial property and biocompatibility of TNZ-5Cu were investigated in detail. The research results have shown that the solid solution treated alloy was mainly composed of β-phase and α″-phase, while the aged alloys of β-phase, α″-phase, α-phase and TiCu. Compared with Ti-13Nb-13Zr alloy (65 GPa) and Ti-6Al-4 V alloy (111 GPa), the elastic modulus of TNZ-5Cu alloy after solution treatment was about 72 GPa and increased with the aging treatment up to 85 GPa, and the hardness was maintained at a higher level than that of Ti-13Nb-13Zr alloys (288 HV). The bacteria plate count results showed that the antibacterial ability of TNZ-5Cu alloy increased with the extension of the aging duration from <60% at 15-30 min to >90% at 1-2 h. Cell experiments showed that all TNZ-5Cu alloy had good cell compatibility. The low modulus and the antibacterial property could provide potential to avoid stress shield and device-related inflection in the clinical application.
Topics: Alloys; Anti-Bacterial Agents; Biocompatible Materials; Elastic Modulus; Materials Testing; Titanium
PubMed: 34082933
DOI: 10.1016/j.msec.2021.112116 -
Materials Science & Engineering. C,... Feb 2021Magnesium (Mg) has mechanical properties similar to human bones and Mg alloy is considered ideal medical implant material. However, the high velocity of degradation...
Magnesium (Mg) has mechanical properties similar to human bones and Mg alloy is considered ideal medical implant material. However, the high velocity of degradation inside the human inner environment severely hampers the usage of Mg alloys. In this study, caerin peptide 1.9 (F3) and a modified sequence of caerin 1.1 (F1) with anti-bacterial activity, were covalently immobilised on the surface of Mg alloys by plasma chemical click reaction. The in vitro antibacterial activity and corrosion resistance of these caerin peptide-immobilised Mg alloys were investigated in Dulbecco's Modified Eagle Medium (DMEM) solution. Un-immobilised Mg alloy sample, blank drug-sensitive tablet (BASD) and a commonly used antibiotics Tazocin were used for comparison. Results showed that peptide immobilised Mg samples showed observable improved corrosion resistance and prolonged antibacterial effect compared to non-immobilised Mg alloy and free caerin peptides. These results indicate that coating Mg alloy with caerin peptides obviously increases the alloy's antibacterial ability and putatively improves the corrosion resistance in vitro. The mechanism underlying the prolonged antibacterial effect for annealed Mg alloys immobilised with the peptides (especially F3) remains unclear, which worth further experimental and theoretical investigation.
Topics: Alloys; Anti-Bacterial Agents; Coated Materials, Biocompatible; Corrosion; Humans; Magnesium; Peptides; Pharmaceutical Preparations; Surface Properties
PubMed: 33579462
DOI: 10.1016/j.msec.2020.111819 -
Materials Science & Engineering. C,... Nov 2016Magnesium (Mg) and its alloys have been extensively explored as potential biodegradable implant materials for orthopaedic applications (e.g. Fracture fixation). However,... (Review)
Review
Magnesium (Mg) and its alloys have been extensively explored as potential biodegradable implant materials for orthopaedic applications (e.g. Fracture fixation). However, the rapid corrosion of Mg based alloys in physiological conditions has delayed their introduction for therapeutic applications to date. The present review focuses on corrosion, biocompatibility and surface modifications of biodegradable Mg alloys for orthopaedic applications. Initially, the corrosion behaviour of Mg alloys and the effect of alloying elements on corrosion and biocompatibility is discussed. Furthermore, the influence of polymeric deposit coatings, namely sol-gel, synthetic aliphatic polyesters and natural polymers on corrosion and biological performance of Mg and its alloy for orthopaedic applications are presented. It was found that inclusion of alloying elements such as Al, Mn, Ca, Zn and rare earth elements provides improved corrosion resistance to Mg alloys. It has been also observed that sol-gel and synthetic aliphatic polyesters based coatings exhibit improved corrosion resistance as compared to natural polymers, which has higher biocompatibility due to their biomimetic nature. It is concluded that, surface modification is a promising approach to improve the performance of Mg-based biomaterials for orthopaedic applications.
Topics: Absorbable Implants; Alloys; Animals; Biomimetics; Corrosion; Humans; Magnesium; Materials Testing
PubMed: 27524097
DOI: 10.1016/j.msec.2016.06.020 -
Acta Biomaterialia Oct 2022Zinc based biodegradable metals (BMs) show great potential to be used in various biomedical applications, owing to their superior biodegradability and biocompatibility.... (Review)
Review
Zinc based biodegradable metals (BMs) show great potential to be used in various biomedical applications, owing to their superior biodegradability and biocompatibility. Some high-strength (ultimate tensile strength > 600 MPa) Zn based BMs have already been developed through alloying and plastic working, making their use in load-bearing environments becomes a reality. However, different from Mg and Fe based BMs, Zn based BMs exhibit significant "strain-softening" effect that leads to limited uniform deformation. Non-uniform deformation is detrimental to Zn based devices or implants, which will possibly lead to unexpected failure. People might be misled by the considerable fracture elongation of Zn based BMs. Thus, it is important to specify uniform elongation as a term of mechanical requirements for Zn based BMs. In this review, recent advances on the mechanical properties of Zn based BMs have been comprehensively summarized, especially focusing on the strain softening phenomenon. At first, the origin and evaluation criteria of strain softening were introduced. Secondly, the effects of alloying elements (including element type, single or multiple addition, and alloying content) and microstructural characteristics (grain size, constituent phase, phase distribution, etc.) on mechanical properties (especially for uniform elongation) of Zn based BMs were summarized. Finally, how to get a good balance between strength and uniform elongation was generally discussed based on the service environment. In addition, possible ways to minimize or eliminate the strain softening effect were also proposed, such as controlling of twins, solute clusters, and grain boundary characteristics. All these items above would be helpful to understand the mechanical instability of Zn based BMs, and to make the full usage of them in the future medical device design. STATEMENT OF SIGNIFICANCE: Biodegradable metals (BMs) is a hotspot in the field of metallic biomaterials. Fracture elongation is normally adopted to quantify the deformability of Mg and Fe based BMs owing to their negligible necking strain, yet the strain softening would occur in Zn based BMs, which is extremely detrimental to performance of their medical device. In this review paper, a better understanding the mechanical performance of Zn-based BMs with the term "uniform elongation" instead of "fracture elongation" was depicted, and possible ways to minimize or eliminate the strain softening effect were also proposed, such as twins, solute clusters, self-stable dislocation network, and grain boundary characteristics. It would be helpful to understand the mechanical instability of Zn based BMs and making full usage of it in the future medical device design.
Topics: Absorbable Implants; Alloys; Biocompatible Materials; Corrosion; Humans; Materials Testing; Plastics; Zinc
PubMed: 36028200
DOI: 10.1016/j.actbio.2022.08.041 -
International Journal of Molecular... Jun 2024The purpose of this study is to evaluate the corrosion resistance in natural seawater (Năvodari area) of two types of low-alloy carbon steels BVDH36 and LRAH36 by...
The purpose of this study is to evaluate the corrosion resistance in natural seawater (Năvodari area) of two types of low-alloy carbon steels BVDH36 and LRAH36 by electrochemical methods. The electrochemical methods used were the evolution of the free potential (OCP), electrochemical impedance spectroscopy (EIS), polarization resistance (R) and corrosion rate (V), potentiodynamic polarization (PD), and cyclic voltammetry (CV). The studies were completed by ex situ characterization analyzes of the studied surfaces before and after corrosion such as: optical microscopy, scanning electron microscopy and X-ray diffraction analysis. The results of the study show us that the polarization resistance of the low-alloy carbon steel BVDH36 is higher compared to the polarization resistance of the low-alloy carbon steel LRAH36. It is also observed that with the increase in the immersion time of the samples in natural seawater, the polarization resistance of the BVDH36 alloy increases over time and finally decreases, and for the carbon steel LRAH36 the polarization resistance increases.
Topics: Corrosion; Seawater; Steel; Alloys; X-Ray Diffraction; Dielectric Spectroscopy; Electrochemical Techniques; Microscopy, Electron, Scanning; Carbon
PubMed: 38928113
DOI: 10.3390/ijms25126405 -
Acta Biomaterialia Apr 2022The existing biodegradable magnesium alloy stent (BMgS) structure is prone to problems, such as insufficient support capacity and early fracture at areas of concentrated...
The existing biodegradable magnesium alloy stent (BMgS) structure is prone to problems, such as insufficient support capacity and early fracture at areas of concentrated stress. Herein, a stent structural design, which reduced the cross section of the traditional sin-wave stent by nearly 30% and introduces a regular arc structure in the middle of the support ring. The influence of the dual-parameter design of bending radius (r) and ring length (L) on plastic deformation, expansion and compression resistance performances are discussed. The non-dominated sorting genetic algorithm II (NSGA-II) was used to search for the optimal solution. It was found that the introduction of parameter r effectively improved the plastic deformation and expansion performance, and the reduction of L improved stent compression resistance. Finally, an optimized stent configuration was obtained. In vitro mechanical tests, including balloon inflation, radial strength and flexibility, verified the simulation results. The radial strength for the optimised stent increases by approximately 40% compared with that for the sinusoidal stent. Microarea X-ray diffraction result shows that the circumferential residual stress for the optimised stent decreases by half compared with that for the sinusoidal stent, thus effectively reducing the stress concentration phenomenon. STATEMENT OF SIGNIFICANCE: Despite current progress in BMgS research, the optimal design of the structure is limited. We present a new type of structurally designed stent. The performance of this stent was analysed by a finite element method and experimentally verified. The structural design positively influenced stent performance.
Topics: Alloys; Finite Element Analysis; Magnesium; Plastics; Prosthesis Design; Stents; Stress, Mechanical
PubMed: 35085798
DOI: 10.1016/j.actbio.2022.01.045 -
Manual polishing of 3D printed metals produced by laser powder bed fusion reduces biofilm formation.PloS One 2019Certain 3D printed metals and surface finishes may be better suited for canine patient specific orthopedic implants on the basis of minimizing potential bacterial... (Comparative Study)
Comparative Study
Certain 3D printed metals and surface finishes may be better suited for canine patient specific orthopedic implants on the basis of minimizing potential bacterial biofilm growth. Thirty disks each of titanium alloy, stainless steel, and cobalt chromium alloy were 3D printed via laser powder bed fusion. Fifteen disks of each metal were subsequently polished. After incubation with a robust biofilm-forming methicillin-resistant Staphylococcus pseudintermedius isolate, disks were rinsed and sonicated to collect biofilm bacteria. Serial dilutions were plated on blood agar, and colony forming units were counted log (ln) transformed for analysis of variance. Interference microscopy quantified surface roughness for comparison to biofilm growth. Scanning electron microscopy on both pre- and post-sonicated disks confirmed biofilm presence and subsequent removal, and visualized surface features on cleaned disks. Significantly more bacteria grew on rough versus polished metal preparations (p < 0.0001). Titanium alloy had more bacterial biofilm growth compared to cobalt chromium alloy (p = 0.0001) and stainless steel (p < 0.0001). There were no significant growth differences between cobalt chromium alloy and stainless steel (p = 0.4737). Relationships between biofilm growth and surface roughness varied: positive with the rough preparations and negative with the smooth. Polished preparations had increased variance in surface roughness compared to rough preparations, and within disk variance predominated over between disk variance for all preparations with the exception of rough cobalt chromium alloy and rough stainless steel. Using scanning electron microscopy, bacterial biofilms tended to form in crevices. Overall, manual polishing of 3D printed surfaces significantly reduced biofilm growth, with preparation-specific relationships between surface roughness and biofilm growth. These results suggest that metallic implants produced by laser powder bed fusion should be polished. Further research will elucidate the optimal surface roughness per preparation to reduce potential biofilm formation and implant associated infection.
Topics: Alloys; Animals; Biofilms; Bone-Anchored Prosthesis; Chromium Alloys; Dogs; Lasers; Methicillin Resistance; Microscopy, Electron, Scanning; Microscopy, Interference; Powders; Printing, Three-Dimensional; Prostheses and Implants; Sonication; Stainless Steel; Staphylococcus; Surface Properties; Titanium
PubMed: 30811509
DOI: 10.1371/journal.pone.0212995 -
Acta Biomaterialia Feb 2020As a biodegradable metal (BM), alloys of magnesium (Mg) offer great potential as an alternative to the permanent metallic implants currently being used for fracture... (Review)
Review
As a biodegradable metal (BM), alloys of magnesium (Mg) offer great potential as an alternative to the permanent metallic implants currently being used for fracture repairs and tissue-healing processes. These alloys exhibit superior biocompatibility and appropriate mechanical strength and dissolution behavior in the physiological environment, essential prerequisites for a BM. However, rapid and generally non-uniform corrosion has been the major drawback of Mg alloys. Abrupt deterioration in mechanical strength is experienced due to the inhomogeneous corrosion, which is also considered detrimental to the surface passivation process. This review has analyzed a variety of strategies that can be adopted to address the core challenges with Mg alloy biomaterials. In addition, the review provides fundamental understanding of the mechanisms associated with these challenging problems, including discussion of crystalline and bulk metallic glasses (BMGs) and composites. Comparison among the properties and mechanisms observed in other metal alloy systems, including zinc (Zn) and iron (Fe) alloys and prominent BMGs, are also presented for analysis in order to provide new approaches to resolving the critical issues of Mg alloys. STATEMENT OF SIGNIFICANCE: The effects of alloying elements, microstructure, heat treatment and deformation on the mechanical and corrosion properties of biodegradable metals such as Mg-based alloys and bulk metal glasses (BMGs) are identified. Theoretical models and experimental findings are comprehensively analyzed to corroborate the actual corrosion and deformation mechanisms observed in biodegradable metals (BMs). This work also provides an in-depth comparison of mechanical and corrosion properties among the prominent biodegradable metal alloy systems, illustrating a clear outlook on their potentials. The proposed strategies to address the current challenges in BMs are substantiated with fundamental theories and experimental evidence.
Topics: Absorbable Implants; Alloys; Animals; Corrosion; Crystallization; Glass; Humans; Magnesium
PubMed: 31881312
DOI: 10.1016/j.actbio.2019.12.023 -
Materials Science & Engineering. C,... Nov 2016Pure Mg and a Mg-6wt.% Zn alloy were investigated as potential candidates for biodegradable implants for the urinary system. The in vitro corrosion behavior was studied...
Pure Mg and a Mg-6wt.% Zn alloy were investigated as potential candidates for biodegradable implants for the urinary system. The in vitro corrosion behavior was studied by potentiodynamic polarization and immersion tests in simulated body fluid (SBF) at 37°C. The in vivo degradation and histocompatibility were examined through implantation into the bladders of Wistar rats. The alloying element Zn elevated the passivation potential and increased the cathodic current density. Both in vitro and in vivo degradation tests showed a faster corrosion rate for the Mg-6Zn alloy. Tissues stained with hematoxylin and eosin (HE) suggested that both pure Mg and Mg-6Zn alloy exhibited good histocompatibility in the bladder indwelling implantation and no differences between pure Mg and Mg-6Zn groups were found in bladder, liver and kidney tissues during the 2weeks implantation. Overall, this work presented instructive information on the degradation properties and histocompatibility of pure Mg and the Mg-6Zn alloy in the urinary system.
Topics: Absorbable Implants; Alloys; Animals; Corrosion; Humans; Kidney; Magnesium; Male; Materials Testing; Rats; Rats, Wistar; Zinc
PubMed: 27524036
DOI: 10.1016/j.msec.2016.06.017 -
Small (Weinheim An Der Bergstrasse,... Apr 2022The design of efficient and sustainable Pt-based catalysts is the key to the development of direct methanol fuel cells. However, most Pt-based catalysts still exhibit...
The design of efficient and sustainable Pt-based catalysts is the key to the development of direct methanol fuel cells. However, most Pt-based catalysts still exhibit disadvantages including unsatisfied catalytic activity and serious CO poisoning in the methanol oxidation reaction (MOR). Herein, highly porous PtAg nanoflowers (NFs) with rich defects are synthesized by using liquid reduction combining chemical etching. It is demonstrated that the proportion of precursors determines the inhomogeneity of alloy elements, and the strong corrosiveness of nitric acid to silver leads to the eventual porous flower-like structure. Impressively, the optimal etched Pt Ag NFs have the mixed defects of surface steps, dislocations, and bulk holes, and their mass activity (1136 mA mg ) is 2.6 times higher than that of commercial Pt/C catalysts, while the ratio of forward and backward peak current density (I /I ) can reach 3.2, exhibiting an excellent anti-poisoning ability. Density functional theory calculations further verify their high anti-poison properties from both an adsorption and an oxidation perspective of CO intermediate. The introduction of Ag makes it easier for CO to be oxidized and removed. This study provides a facile approach to prepare rich defects and porous alloy with excellent MOR performance and superior anti-poisoning ability.
Topics: Alloys; Catalysis; Methanol; Porosity; Silver
PubMed: 35224851
DOI: 10.1002/smll.202106643