Biodegradable Implantation Material: Mechanical Properties and Surface Corrosion Mechanism of Mg-1Ca-0.5Zr Alloy

Synergistic Improvement of Antibacterial and Osteogenic Differentiation of Thermomechanically Processed Mg-Zr-Sr-Ce Alloy: Insights into the Role of Precipitate Evolution Supported by AIMD Simulation Study

In the present study, we have discussed the influence of forging temperature (623 K (FT623), 723 K (FT723) and 823 K (FT823)) on microstructure and texture evolution and its implication on mechanical behavior, in vitro-in vivo biocorrosion, antibacterial response, and cytocompatibility of microalloyed Mg-Zr-Sr-Ce alloy. Phase analysis, SEM, and TEM characterization confirm the presence of Mg12Ce precipitate, and its stability was further validated by performing ab initio molecular dynamic simulation study. FT723 exhibits strengthened basal texture, higher fraction of second phases, and particle-stimulated nucleation-assisted DRX grains compared to other two specimens, resulting in superior strength with comparable ductility. FT723 also exhibits superior corrosion resistance mainly due to the strengthened basal texture and lower dislocation density. All the specimens exhibit excellent antibacterial behavior with Gram-negative E. coli, Gram-positive Staphylococcus aureus, and Pseudomonas aeruginosa bacteria. 100% reduction of bacterial growth is observed within 24 h of culture of the specimens. Cytocompatibility was determined by challenging specimen extracts with the MC3T3-E1 cell lines. FT723 specimen exhibits the highest cell proliferation and alkaline phosphatase activity (ALP) because of its superior corrosion resistance. The ability of the specimens to be used in orthopedic implant application was evaluated by in vivo study in rabbit femur. Neither tissue-related infection nor the detrimental effect surrounding the implant was confirmed from histological analysis. Significant higher bone regeneration surrounding the FT723 specimen was observed in SEM analysis and fluorochrome labeling. After 60 days, the FT723 specimen exhibits the highest bone formation, suggesting it is a suitable candidate for orthopedic implant application.

Electroless Deposits of ZnO and Hybrid ZnO/Ag Nanoparticles on Mg-Ca0.3 Alloy Surface: Multiscale Characterization

ZnO and hybrid of ZnO/Ag structures in the nanometer size were electroless deposited on the Mg-Ca0.3 alloy surface, achieved from aqueous solutions (10−3 M at 21 °C) of ZnO (suspension), Zn(NO3)2 and AgNO3. The surface characterization of the deposits was carried out by Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS), X-Ray Photoelectron Spectroscopy (XPS), Fourier transform infrared (FTIR), UV-Visible and Raman spectroscopy. The nanoparticles (NPs) area size distribution analysis revealed that the average of ZnO-NPs was ~85 nm. Likewise, the Ag-NPs of electroless deposits had an average area size of ~100 nm and nucleated in the vicinity of ZnO-NPs as Ag+ ions have been attracted by the negatively charged O2− atoms of the Zn-O dipole. The ZnO-NPs had the wurtzite structure, as indicated by Raman spectroscopy analysis and XRD complementary analysis. The UV-Visible spectroscopy analysis gave a peak at ~320 nm associated with the decrease in the imaginary part (k) of the refractive index of Ag-NPs. On the Mg-Ca0.3 surface, MgO, Mg(OH)2 and MgCO3 are present due to the Mg-matrix. XRD spectra of Ag-NPs indicated the presence of planes arranged with the FCC hexagonal structure. The reported hybrid ZnO/Ag electroless deposits of NPs are of interest for temporary implant devices, providing antibacterial properties to Mg-Ca0.3 surface, a widely used biodegradable material.

Potential bioactive coating system for high-performance absorbable magnesium bone implants

Magnesium alloys are considered the most suitable absorbable metals for bone fracture fixation implants. The main challenge in absorbable magnesium alloys is their high corrosion/degradation rate that needs to be controlled. Various coatings have been applied to magnesium alloys to slow down their corrosion rates to match their corrosion rate to the regeneration rate of the bone fracture. In this review, a bioactive coating is proposed to slow down the corrosion rate of magnesium alloys and accelerate the bone fracture healing process. The main aim of the bioactive coatings is to enhance the direct attachment of living tissues and thereby facilitate osteoconduction. Hydroxyapatite, collagen type I, recombinant human bone morphogenetic proteins 2, simvastatin, zoledronate, and strontium are six bioactive agents that show high potential for developing a bioactive coating system for high-performance absorbable magnesium bone implants. In addition to coating, the substrate itself can be made bioactive by alloying magnesium with calcium, zinc, copper, and manganese that were found to promote bone regeneration.

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Bioactive-coated magnesium implant could accelerate bone fracture healing time to match with magnesium degradation.

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Hydroxyapatite, collagen type I, recombinant human bone morphogenetic proteins 2, simvastatin, zoledronate, and strontium are high potential bioactive coating materials.

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The incorporation of Ca, Zn, Cu, Sr, and Mn in Mg base-metal could further enhance bone formation.

Microstructure and In Vitro Evaluation of Extruded and Hot Drawn Alloy MgCa0.7 for Biodegradable Surgical Wires

The MgCa0.7 alloy may be a promising material for biodegradable surgical wires. In this paper, the technology for producing surgical wires from this alloy has been developed, based both on finite element modelling and experimental study. In particular, the extrusion and hot-drawing effects on the mechanical properties, microstructures, in-vitro rates of biocorrosion, and cytotoxicity to human cancer cells (SaOS-2) and healthy (hPDL) ones, have been determined. An approximately 30–40% increase in corrosion rate due to increasing hot-drawing temperature was observed. An effect of hot-drawing temperature on cytotoxicity was also found. Notably, at various stages of the final wires’ production, the MgCa0.7 alloy became toxic to cancer cells. This cytotoxicity depended on the alloys’ processing parameters and was maximal for the as-extruded rod and for the wires immediately after hot drawing at 440 °C. Thus, the careful selection of processing parameters makes it possible to obtain a product that is not only a promising candidate for biodegradable surgical wires, but one which also has intrinsic bioactive properties that produce antitumor activity.

Graphene Family Nanomaterial Reinforced Magnesium-Based Matrix Composites for Biomedical Application: A Comprehensive Review

Together with the enhancement of the load-bearing implant process for bone substitution and reproduction, an increasing requirement was observed concerning biodegradable magnesium and its alloys with lighter density and outstanding characteristics. Regardless of the current great potential of Mg utilization currently, the broader use of Mg alloys continues to be constrained by several natural causes, such as low resistance of corrosion, inadequate mechanical integrity during the healing process, and poor antibacterial performance. In this perspective, Mg-based composite encapsulated within graphene family nanomaterials (GFNs) such as graphene (Gr), graphene oxide (GO), graphene nanoplatelets (GNPs), and reduced graphene oxide (rGO) as reinforcement agents present great antibacterial activity, as well as cellular response and depicted numerous benefits for biomedical use. Magnesium matrix nanocomposites reinforced with GFNs possess enhanced mechanical properties and high corrosion resistance (low concentration graphene). It is worth noting that numerous elements including the production technique of the Mg-based composite containing GFNs and the size, distribution, and amounts of GFNs in the Mg-based matrix have a crucial role in their properties and applications. Then, the antibacterial mechanisms of GFN-based composite are briefly described. Subsequently, the antibacterial and strengthening mechanisms of GFN-embedded Mg-based composites are briefly described. This review article is designed to wrap up and explore the most pertinent research performed in the direction of Mg-based composites encapsulated within GFNs. Feasible upcoming investigation directions in the field of GFN-embedded Mg-based composites are discussed in detail.

Failure Analysis of Biometals

Metallic biomaterials (biometals) are widely used for the manufacture of medical implants, ranging from load-bearing orthopaedic prostheses to dental and cardiovascular implants, because of their favourable combination of properties including high strength, fracture toughness, biocompatibility, and wear and corrosion resistance [...]