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Journal of Neural Engineering Apr 2018This review paper shows that tungsten should not generally be used as a chronically implanted material. The metal has a long implant history, from neuroscience, vascular... (Review)
Review
This review paper shows that tungsten should not generally be used as a chronically implanted material. The metal has a long implant history, from neuroscience, vascular medicine, radiography, orthopaedics, prosthodontics, and various other fields, primarily as a result of its high density, radiopacity, tensile strength, and yield point. However, a crucial material criterion for chronically implanted metals is their long-term resistance to corrosion in body fluids, either by inherently noble metallic surfaces, or by protective passivation layers of metal oxide. The latter is often assumed for elemental tungsten, with references to its 'inertness' and 'stability' common in the literature. This review argues that in the body, metallic tungsten fails this criterion, and will eventually dissolve into the soluble hexavalent form W, typically represented by the orthotungstate [Formula: see text] (monomeric tungstate) anion. This paper outlines the metal's unfavourable corrosion thermodynamics in the human physiological environment, the chemical pathways to either metallic or metal oxide dissolution, the rate-limiting steps, and the corrosion-accelerating effects of reactive oxidising species that the immune system produces post-implantation. Multiple examples of implant corrosion have been reported, with failure by dissolution to varying extents up to total loss, with associated emission of tungstate ions and elevated blood serum levels measured. The possible toxicity of these corrosion products has also been explored. As the field of medical implants grows and designers explore novel solutions to medical implant problems, the authors recommend the use of alternative materials.
Topics: Animals; Biocompatible Materials; Corrosion; Humans; Materials Testing; Prostheses and Implants; Time Factors; Tungsten
PubMed: 29300000
DOI: 10.1088/1741-2552/aaa502 -
Cell Biology International Aug 2021Metallic materials are commonly used for load-bearing implants and as internal fixation devices. It is customary to use austenitic stainless steel, especially surgical... (Review)
Review
Metallic materials are commonly used for load-bearing implants and as internal fixation devices. It is customary to use austenitic stainless steel, especially surgical grade type 316L SS as temporary and Ti alloys as permanent implants. However, long-term, poor bonding with bone, corrosion, and release of metal ions, such as chromium and nickel occur. These ions are powerful allergens and carcinogens and their uncontrolled leaching may be avoided by surface coatings. Therefore, bioactive glasses (BGs) became a vital biomedical material, which can form a biologically active phase of hydroxycarbonate apatite on their surface when in contact with physiological fluids. To reduce the high coefficient of friction and the brittle nature of BGs, polymers are normally incorporated to avoid the high-temperature sintering/densification of ceramic-only coatings. For medical application, electrophoretic deposition (EPD) is now used for polymer (organic) and ceramic (inorganic) components at room temperature due to its simplicity, control of coating thickness and uniformity, low cost of equipment, ability to coat substrates of intricate shape and to supply thick films in composite form, high purity of deposits as well as no phase transformation during coating. Although extensive research has been conducted on polymer/inorganic composite coatings, only some studies have reported multifunctional properties, such as biological antibacterial activity, enhanced cell adhesion, controlled drug release ability, and mechanical properties. This review will focus on biodegradable coatings, including zien, chitosan, gelatin, cellulose loaded with antibacterial drugs/metallic ions/natural herbs on biostable substrates (PEEK/PMMA/PCL/PLLA layers), which have the potential of multifunctional coating for metallic implants.
Topics: Alloys; Animals; Anti-Bacterial Agents; Biocompatible Materials; Chitosan; Drug Implants; Gelatin; Humans; Materials Testing; Metals
PubMed: 33818836
DOI: 10.1002/cbin.11604 -
International Journal of Molecular... Aug 2020Carbonic anhydrases (CAs) and metallothioneins (MTs) are both families of zinc metalloproteins central to life, however, they coordinate and interact with their Zn ion... (Review)
Review
Carbonic anhydrases (CAs) and metallothioneins (MTs) are both families of zinc metalloproteins central to life, however, they coordinate and interact with their Zn ion cofactors in completely different ways. CAs and MTs are highly sensitive to the cellular environment and play key roles in maintaining cellular homeostasis. In addition, CAs and MTs have multiple isoforms with differentiated regulation. This review discusses current literature regarding these two families of metalloproteins in carcinogenesis, with a dialogue on the association of these two ubiquitous proteins in vitro in the context of metalation. Metalation of CA by Zn-MT and Cd-MT is described. Evidence for protein-protein interactions is introduced from changes in metalation profiles of MT from electrospray ionization mass spectrometry and the metalation rate from stopped-flow kinetics. The implications on cellular control of pH and metal donation is also discussed in the context of diseased states.
Topics: Animals; Cadmium; Carbonic Anhydrases; Humans; Metalloproteins; Metallothionein; Metals; Models, Molecular; Protein Binding; Protein Conformation; Spectrometry, Mass, Electrospray Ionization; Zinc
PubMed: 32784815
DOI: 10.3390/ijms21165697 -
Metallomics : Integrated Biometal... Nov 2018MTs are small cysteine-rich proteins that chelate metal ions such as Cu+ and Zn2+, and are widely distributed in several life domains, in particular the eukaryotic one.... (Review)
Review
MTs are small cysteine-rich proteins that chelate metal ions such as Cu+ and Zn2+, and are widely distributed in several life domains, in particular the eukaryotic one. They are present in the following phyla: Opisthokonta (mainly Fungi and Metazoa), Chloroplastida, Alveolata (ciliates) and Excavata (Trichomonas) for Eukaryota and Cyanobacteria, Actinobacteria, Proteobacteria and Firmicutes for Bacteria. However, their absence in some phyla underlines that MTs are far from being fully known. The MT amino acid sequences show a great diversity of sizes and structures both in terms of cysteine motifs and organization of these motifs. This review also highlights the different oxidized, apoprotein and metalated forms of MTs, the diversity of interactions they can establish with different molecules and their central and multifunctional cellular role. We present MTs as a protein system that could be a hub in molecular interaction networks. Studying MTs as a hub in cellular interaction networks should provide new insights for a better understanding of MT functioning and cellular processes.
Topics: Eukaryotic Cells; Metabolic Networks and Pathways; Metallothionein; Metals
PubMed: 30229264
DOI: 10.1039/c8mt00165k -
Internal Medicine Journal Feb 2024The first dedicated tracheobronchial silicone stent was designed by the French pulmonologist Jean-Paul Dumon. The most common indications for stenting are to minimise... (Review)
Review
The first dedicated tracheobronchial silicone stent was designed by the French pulmonologist Jean-Paul Dumon. The most common indications for stenting are to minimise extrinsic airway compression from mass effect, maintain airway patency due to intrinsic obstruction or treat significant nonmalignant airway narrowing or fistulae. Silicone stents require rigid bronchoscopy for insertion; however, they are more readily repositioned and removed compared with metallic stents. Metallic stents demonstrate luminal narrowing when loads are applied to their ends, therefore stents should either be reinforced at the ends or exceed the area of stenosis by a minimum of 5 mm. Nitinol, a nickel-titanium metal alloy, is currently the preferred material used for airway stents. Airway stenting provides effective palliation for patients with severe symptomatic obstruction. Drug-eluting and three-dimensional printing of airway stents present promising solutions to the challenges of the physical and anatomical constraints of the tracheobronchial tree. Biodegradable stents could also be a solution for the treatment of nonmalignant airway obstruction.
Topics: Humans; Bronchoscopy; Airway Obstruction; Silicones; Metals; Stents; Treatment Outcome; Nickel; Titanium
PubMed: 38140778
DOI: 10.1111/imj.16304 -
Small (Weinheim An Der Bergstrasse,... Jun 2023DNA origami molds allow a shape-controlled growth of metallic nanoparticles. So far, this approach is limited to gold and silver. Here, the fabrication of linear...
DNA origami molds allow a shape-controlled growth of metallic nanoparticles. So far, this approach is limited to gold and silver. Here, the fabrication of linear palladium nanostructures with controlled lengths and patterns is demonstrated. To obtain nucleation centers for a seeded growth, a synthesis procedure of palladium nanoparticles (PdNPs) using Bis(p-sulfonatophenyl)phenylphosphine (BSPP) both as reductant and stabilizer is developed to establish an efficient functionalization protocol of the particles with single-stranded DNA. Attaching the functionalized particles to complementary DNA strands inside DNA mold cavities supports subsequently a highly specific seeded palladium deposition. This provides rod-like PdNPs with diameters of 20-35 nm of grainy morphology. Using an annealing procedure and a post-reduction step with hydrogen, homogeneous palladium nanostructures can be obtained. With the adaptation of the procedure to palladium the capabilities of the mold-based tool-box are expanded. In the future, this may allow a facile adaptation of the mold approach to less noble metals including magnetic materials such as Ni and Co.
Topics: Palladium; Metal Nanoparticles; Nanostructures; DNA; Gold
PubMed: 36960479
DOI: 10.1002/smll.202206438 -
Material Processing and Design of Biodegradable Metal Matrix Composites for Biomedical Applications.Annals of Biomedical Engineering Sep 2018In recent years, biodegradable metallic materials have played an important role in biomedical applications. However, as typical for the metal materials, their structure,... (Review)
Review
In recent years, biodegradable metallic materials have played an important role in biomedical applications. However, as typical for the metal materials, their structure, general properties, preparation technology and biocompatibility are hard to change. Furthermore, biodegradable metals are susceptible to excessive degradation and subsequent disruption of their mechanical integrity; this phenomenon limits the utility of these biomaterials. Therefore, the use of degradable metals, as the base material to prepare metal matrix composite materials, it is an excellent alternative to solve the problems above described. Biodegradable metals can thus be successfully combined with other materials to form biodegradable metallic matrix composites for biomedical applications and functions. The present article describes the processing methods currently available to design biodegradable metal matrix composites for biomedical applications and provides an overview of the current existing biodegradable metal systems. At the end, the manuscript presents and discusses the challenges and future research directions for development of biodegradable metallic matrix composites for biomedical purposes.
Topics: Absorbable Implants; Biocompatible Materials; Biomedical Technology; Metals
PubMed: 29869105
DOI: 10.1007/s10439-018-2058-y -
The Journal of Biological Chemistry Oct 2014Mononuclear iron enzymes can tightly bind non-activating metals. How do cells avoid mismetallation? The model bacterium Escherichia coli may control its metal pools so... (Review)
Review
Mononuclear iron enzymes can tightly bind non-activating metals. How do cells avoid mismetallation? The model bacterium Escherichia coli may control its metal pools so that thermodynamics favor the correct metallation of each enzyme. This system is disrupted, however, by superoxide and hydrogen peroxide. These species oxidize ferrous iron and thereby displace it from many iron-dependent mononuclear enzymes. Ultimately, zinc binds in its place, confers little activity, and imposes metabolic bottlenecks. Data suggest that E. coli compensates by using thiols to extract the zinc and by importing manganese to replace the catalytic iron atom. Manganese resists oxidants and provides substantial activity.
Topics: Cations, Divalent; Escherichia coli; Escherichia coli Proteins; Gene Expression; Hydrogen Peroxide; Iron; Manganese; Metalloproteins; Oxidation-Reduction; Oxidative Stress; Structure-Activity Relationship; Superoxides; Zinc
PubMed: 25160623
DOI: 10.1074/jbc.R114.588814 -
World Journal of Microbiology &... Apr 2019Metal corrosion is a major global concern in many economic sectors. The degradation of metal surfaces is responsible for losses in values that account for about 3% of... (Review)
Review
Metal corrosion is a major global concern in many economic sectors. The degradation of metal surfaces is responsible for losses in values that account for about 3% of gross domestic product (GDP) only in the US. Parts of all corrosion processes described in different environments are present mainly in marine environments. The marine environment is characterized as favoring the corrosion processes of several metallic alloys, damaging structures used in the construction of ships, ports, oil pipelines, and others. Despite chemical corrosion being the most frequently described in these environments, studies show the participation of microorganisms in direct corrosion processes or in the acceleration/influence of the corrosive action, through the formation of complex biofilms. These structures create favorable conditions for microorganisms to degrade metal surfaces, causing damage known as pitting and crevices. Currently, diverse technicians are employed in biocorrosion research, e.g. electronic microscopy, and DNA sequencing. These techniques have clarified the dynamic process of the formation of biofilm structures, allowing understanding of the succession of different species during the evolution of the structure. Improving the understanding of how this interaction between biofilm and metallic surface occurs will enable better evaluation of strategies to avoid or decelerate the degradation of metallic structures in marine environments.
Topics: Alloys; Bacteria; Bacterial Adhesion; Bacterial Physiological Phenomena; Biofilms; Corrosion; Electrochemistry; Metals; Seawater; Steel; Surface Properties
PubMed: 31037431
DOI: 10.1007/s11274-019-2647-4 -
Mini Reviews in Medicinal Chemistry 2015Along with the exuberant development of nanotechnology, a large number of nanoformulations or non materials are successfully applied in the clinics, biomedicine,... (Review)
Review
Along with the exuberant development of nanotechnology, a large number of nanoformulations or non materials are successfully applied in the clinics, biomedicine, cosmetics and industry. Despite some unique advantages of nanoformulations, there exist potentially worrying toxic effects, particularly those related to metal and metal-containing nanoparticles (NPs). Although various researches have been conducted to assess the metallic and metal-containing nanoparticles toxic effects, only little is known about the toxicity expressive types and evaluation, reasons and mechanisms, influencing factors and research methods of metal and metal-containing nanotoxicity. Therefore, it is of importance to acquire a better understanding of metal and metal-containing nanoparticles toxicity for medical application. This review presents a summary on the metal and metal-containing nanoparticles toxicity research progress consulting relevant literature.
Topics: Animals; Cell Line; Humans; Metals; Mutagenicity Tests; Nanoparticles
PubMed: 25934980
DOI: 10.2174/138955751507150424104334