Biodegradable Bone Implants Research Articles

Development of Fe-Mg alloys with intermediate degradation kinetics as potential biodegradable bone implants

This paper reports the production and characterizations of some Fe-xMg (x=3, 5, 7 wt.%) alloys. These Fe-Mg alloys were prepared using the mechanical alloying method followed by low-temperature sintering. The influence of the addition of various Mg contents on the microstructures, hardness, and degradation characteristics of these alloys were examined. The microstructure analyses demonstrated the homogeneous distribution of Fe and Mg in the alloys with a single-phase BCC structure. The inclusion of Mg was found to affect the alloys’ porosity, particle morphology, grain size, formation of corrosion products, and degradation behaviors. The corrosion products obtained from the alloys using the electrochemical and weight loss measurements indicated that their degradation rates (in the range of 3.13–4.7 mm/year) are in-between those of pure Fe and Mg. It was asserted that the Fe-Mg can be an appealing alternative for temporary medical implants. Furthermore, this study may establish an essential foundation for the degradation control of Fe-based implants by including more active elements.

Investigation of the Microstructure, Mechanical Properties, in Vitro Degradation Behavior, and Biocompatibility of Newly Developed Zn‐0.6%Li Alloy

Zn–Li alloys are considered as one of the promising materials in biodegradable bone implants because they have excellent biocompatibility and high strength. This study examines the extrusion deformation effects on the microstructure, mechanical characteristics, in vitro degradation behavior, and biocompatibility of Zn‐0.6Li alloy. It is shown that primary α‐Zn and LiZn4 precipitates of as‐extruded Zn‐0.6Li alloy are significantly refined. The dendritic primary α‐Zn is refined into fine equiaxed grains. The eutectic (α‐Zn + LiZn4) lamellar spacing distributed in dendrites are refined from 0.86 ± 0.5 to 0.57 ± 0.4 μm. The extruded Zn‐0.6Li alloy of the yield strength, ultimate tensile strength, and elongation are significantly enhanced, reaching 365, 498 MPa, and 13.55%, respectively. In Hanks’ solution, the electrochemical corrosion rate and immersion corrosion rate of extruded Zn‐0.6Li alloy are 1.479 ± 0.061 and 0.878 ± 0.006 mm year−1. In addition, the cytotoxicity test and CCK‐8 evaluation demonstrate that the extruded Zn‐0.6Li alloy displays a good biocompatibility.

Degradation Behavior of Medical MgZZC-1 in Various Simulated Body Fluids.

Magnesium-based biodegradable metal bone implants exhibit superior mechanical properties compared to biodegradable polymers for orthopedic and cardiovascular stents. In this study, MgZZC-x (x = 1, 1.2) alloys were screened by in vitro biocompatibility tests in three simulated body fluids under nontoxic conditions. The MgZZC-1 alloys with better biocompatibility were selected to predict the days required for complete degradation. The evolution of degradation products was analyzed, and the mechanism of formation of the product film was inferred. A degradation kinetic model was established to investigate the effect of MEM components on the degradation of the alloys. The results demonstrate that the proteins in MEM can greatly retard the degradation progress by attaching to the surface of MgZZC-1 alloys, which are predicted to degrade completely within 341 days. The carbonate and phosphate buffers were adjusted to pH in MEM solution, delaying the degradation of magnesium alloys. This process in MEM more accurately reflects the actual degradation in the body and is superior to that in Hanks and SBF solutions. This study will promote the application of biodegradable materials in clinical medicine.

Experimental Study of the Corrosive and Biocompatible Properties of Bioresorbable Mg-Ca-Zn Alloy Implants

Introduction. Magnesium and its alloys are used as biodegradable bone implants due to their high biocompatibility, however, the problem of use is rapid biodegradation with loss of strength.The purpose of the study. Experimental evaluation of bioresorbable Mg-Ca-Zn alloy implants in vitro and in bone tissue in vivo, in order to determine the optimal rate of biodegradation, biocompatibility and reparative response of bone tissue.Materials and methods. Samples from the obtained Mg-Ca-Zn alloy were coated in a microarc oxidation bath (MDO), and to further determine the optimal phase composition and surface properties, the samples were kept in an electrolyte. The biodegradation of implants was assessed by the loss of mass of samples in vitro, and the release of gas into bone tissue in vivo, and the biocompatibility and reparative response of bone tissue density.Results. All Mg-Ca-Zn coated samples show reduced weight loss compared to the uncoated sample. Magnesium samples with a 20-minute exposure in electrolyte, in the context of its application in anatomically unloaded areas, showed the optimal rate of biodegradation, biocompatibility and reparative response of bone tissue.Discussion. In our study using the microarc oxidation for control the corrosion resistance samples of magnesium alloy shows good biocompatibility and low corrosion rate. We found 5-fold increase in corrosion resistance in coated implants, compared with uncoated samples.Сonclusion. The results of an experimental evaluation of bioresorbable Mg-Ca-Zn alloy implants in vitro and in bone tissue in vivo showed that Mg-Ca-Zn coated samples demonstrate low weight loss during biodegradation, with minimal gas release into the bone.

Composite of Magnesium and Carbonate Apatite for Biodegradable Bone Implants: A Comparative Study on Sintering and Extrusion Techniques

Developing biodegradable bone implants using magnesium-based materials has garnered significant attention in research. Magnesium offers favorable properties, such as low density, biocompatibility, elastic modulus like bone, and high toxicity limits. However, improvements are needed in mechanical properties and degradation rate. This study focuses on enhancing these properties by developing a novel composite of magnesium with carbonate apatite (CA) reinforcement, Mg/5CA. Compared to hydroxyapatite (HA), CA offers better absorption and avoids fibrotic tissue formation. However, CA undergoes carbonate decomposition during sintering, leading to composite degradation. To address this, an extrusion process is employed to prevent carbonate decomposition. The advanced sintering and extrusion compaction processes are compared for the Mg/5CA composite, examining density, microstructure, hardness, compressive strength, and biocorrosion. Results demonstrate that extrusion increases relative density while CA slightly reduces it. Microstructural analysis reveals finer and elongated grains, tighter bonding between CA and Mg particles, and reduced microporosity in the extruded composite. Mechanical properties, including hardness distribution and compressive strength, are improved in the extruded composite, and the degradation rate decreases compared to sintering. Overall, the extrusion process effectively enhances Mg/5CA composite properties, positioning it as a promising manufacturing technique for biodegradable implant materials. This research contributes to the development of advanced biodegradable implants, which can have significant applications in the field of medical science. Further investigations in this area can contribute to the ongoing advancements in biodegradable implant technology.

A comparison of deep learning segmentation models for synchrotron radiation based tomograms of biodegradable bone implants

Introduction: Synchrotron radiation micro-computed tomography (SRμCT) has been used as a non-invasive technique to examine the microstructure and tissue integration of biodegradable bone implants. To be able to characterize parameters regarding the disintegration and osseointegration of such materials quantitatively, the three-dimensional (3D) image data provided by SRμCT needs to be processed by means of semantic segmentation. However, accurate image segmentation is challenging using traditional automated techniques. This study investigates the effectiveness of deep learning approaches for semantic segmentation of SRμCT volumes of Mg-based implants in sheep bone ex vivo.Methodology: For this purpose different convolutional neural networks (CNNs), including U-Net, HR-Net, U²-Net, from the TomoSeg framework, the Scaled U-Net framework, and 2D/3D U-Net from the nnU-Net framework were trained and validated. The image data used in this work was part of a previous study where biodegradable screws were surgically implanted in sheep tibiae and imaged using SRμCT after different healing periods. The comparative analysis of CNN models considers their performance in semantic segmentation and subsequent calculation of degradation and osseointegration parameters. The models’ performance is evaluated using the intersection over union (IoU) metric, and their generalization ability is tested on unseen datasets.Results and discussion: This work shows that the 2D nnU-Net achieves better generalization performance, with the degradation layer being the most challenging label to segment for all models.

A novel biodegradable nanocrystalline Zn alloy with exceptional biocompatible and antibacterial properties

The development of biodegradable Zn alloys with comprehensive performance for biomedical applications is still challenging. Hence, the nanocrystalline Zn–Cu–Sr–Li alloys were prepared by alloying design and multi-pass high-speed hot rolling. The Zn–3Cu-0.2Sr-0.4Li alloy achieved nanoscale microstructures, resulting in high strength and an ideal corrosion rate that is more suitable for tissue repair cycles. Scanning Kelvin probe force microscopy analysis revealed the potential from high to low was ranked as: ε phase > SrZn13 phase > Zn grains > β phase. The nanoscale Zn grains and β particles formed numerous microcells, enhancing the microgalvanic corrosion effect. The Sr ions could be released more efficiently during the degradation in Li-containing alloys, which endowed the alloys with outstanding biocompatibility. Besides, the synergistic release of Zn ions and Cu ions during alloy degradation endowed the alloy with excellent antimicrobial ability against Staphylococcus aureus (inhibition zone diameter ≈ 7.5 mm). The antimicrobial ability of Zn–3Cu–0.2Sr–0.4Li alloy was superior among the reported biodegradable Zn alloys. These results demonstrated nanocrystalline Zn–Cu–Sr–Li alloys have comprehensive performance and broad application prospects in biodegradable bone implants, providing the experimental and theoretical basis for future research in the biomedical field.

Influence of Preheat Temperature Variation on Single Screw Extrusion for Characterizing PLA, PCL, and HA Biocomposite Filaments

Fractures and ligament injuries often require bone fixation, commonly through Open Reduction and Internal Fixation (ORIF) with compression plates and screws. Additive manufacturing (AM) techniques are considered sustainable due to their potential to reduce emissions and have a minimal adverse impact on the environment. Currently, there is extensive research into producing biocomposite filaments, though there remains limited exploration of the impact of preheat temperature on filament properties. This research explores the effects of varying preheat temperatures in a single screw extruder to achieve biocomposite filament as candidate for biodegradable bone implants. Biocomposite filaments made from Polylactic Acid (PLA) and Polycaprolactone (PCL) in an 85:15 ratio, with 5% hydroxyapatite (HA) derived from green mussel shell waste. Biocomposite mixture was cut into sub-5mm fragments and extruded at 175°C with preheat temperatures between 159°C and 168°C. Filaments were used to fabricate specimens via a 3D printer, following ASTM D790 standards. Specimens were analyzed using X-Ray Diffractometer, Fourier Transform Infrared, Scanning Electron Microscope, density measurements, three-point bending tests, and biodegradation assessments. Results show that preheat temperature variations significantly affect the filament’s crystallinity index, impacting density and mechanical properties. Higher preheat temperatures result in a lower crystallinity index, decreasing density and potentially increasing degradation rates.

Use of Multi-pass FSP treatment for improving mechanical properties and corrosion resistance of Mg-2Zn-HA composite

Magnesium (Mg) alloys are very popular among the biomaterials for biodegradable bone implants due to their suitable properties matching with that of human cortical bone. However, their poor corrosion resistance in biological fluid is a major constraint to become an ideal choice for bioimplants. The corrosion resistance of Mg-alloys is further retarded with microstructural impurities such as micro-pores, micro cracks, heterogeneous distribution of alloying element etc., which is commonly present in as-cast Mg-alloys. In present study, Friction stir processing (FSP) has been performed on Mg-2Zn alloy to refine the microstructures as well as to develop Mg-Zn-HA composites by using HA powder reinforcement. HA powder reinforcement was added using micro-grooves and multiple FSP passes on as-cast Mg-2Zn alloy having average grain size of 63.86 µm. Filling HA powder in 2-grooves and using 3-pass FSP, a refined microstructure having an average grain size of 7.15 µm and homogeneous distribution of HA powder was obtained for the developed Mg-Zn-HA composite. The Mg-Zn-HA composite developed with 3-pass FSP treatment has shown significant improvement in tensile strength and corrosion resistance as compared with as-cast Mg-alloy.

Improving cell proliferation using polylactic acid, polycaprolactone, hydroxyapatite and zinc oxide nanocomposite for cancellous bone substitutes

ABSTRACT Different types of implants are used in orthopedic applications. Due to the stress shielding and a second surgery caused by applying metal implants as orthopedic joints, using biodegradable bone implants with antibacterial properties is advantageous. Therefore, this study aims at fabricating a multifunctional poly (lactic acid) (PLA)-polycaprolactone (PCL)-based scaffold reinforced with hydroxyapatite (HA) and zinc oxide (ZnO) nanoparticles. Solvent casting combined with die-casting techniques was employed for fabricating the scaffolds, and their physical, mechanical, and biological properties were characterized. The morphology of the samples and the growth of hydroxyapatite crystals on the surface of the samples were examined by field emission scanning electron microscope. In dry conditions, adding nanoparticles to the scaffolds has significantly (p < .05) increased the tensile Young’s modulus from 450.00 ± 87.18 MPa to 1050.66 ± 104.05 MPa. Also, adding ZnO has improved the antibacterial properties of the scaffolds against S.aureus and E.coli bacteria strains. Moreover, the MTT assay results (after 72 h cell culture) show that the viability of L929 cells has increased from 22.18 ± 0.62% for the PLA-PCL scaffold to 70.03 ± 0.25% for the optimal nanostructure (p < .05). In conclusion, the PCL-PLA/HA/1% ZnO scaffold could potentially be used as absorbable spongy bone implants.

Pushing boundaries in 3D printing: Economic pressure filament extruder for producing polymeric and polymer-ceramic filaments for 3D printers

3D printing technology can deliver tailored, bioactive, and biodegradable bone implants. However, producing the new, experimental material for a 3D printer could be the first and one of the most challenging steps of the whole bone implant 3D printing process. Production of polymeric and polymer-ceramic filaments involves using costly filament extruders and significantly consuming expensive medical-grade materials. Commercial extruders frequently require a large amount of raw material for experimental purposes, even for small quantities of filament. In our publication, we propose a simple system for pressure filament extruding, which allows obtaining up to 1-meter-long filament suitable for fused filament fabrication-type 3D printers, requiring only 30 g of material to begin work. Our device is based on stainless steel pipes used as a container for material, a basic electric heating system with a proportional–integral–derivative controller, and a pressurised air source with an air pressure regulator. We tested our device on various mixes of polylactide and polycaprolactone with β-tricalcium phosphate and demonstrated the possibility of screening production and testing of new materials for 3D-printed bone implants.

Third-generation biodegradable bone implants: A novel Mg-1Zn-0.5Sc alloy treated by laser shock peening to improve its characteristics

Magnesium (Mg) and its alloys are of much interest as promising third-generation bio-materials for bone implant applications; however, challenges remain for the alloy's mechanical integrity and bio-corrosion behaviour. Therefore, appropriate alloying elements and surface-modification techniques are required to overcome these limitations. Zinc and scandium were found to possess good biocompatibility and biodegradability, in addition to magnesium. This study aims to enhance the mechanical integrity and bio-corrosion resistance behaviour of a novel Mg-1wt% Zn-0.5wt% Sc cast alloy by laser shock peening surface treatment with multiple passes (LSP-2 pass and LSP-3 pass). The microstructural and texture evolution was investigated using various techniques, including field emission scanning electron microscopy with energy-dispersive spectroscopy (FESEM-EDS), optical microscopy (OM), X-ray diffraction (XRD) analysis, electron back-scattered diffraction analysis (EBSD), as well as the surface residual stress, wettability, microhardness, tensile strength, electrochemical polarization test, and biocompatibility were analysed on as-cast, LSP-2 pass and LSP-3 pass specimens. LSP induced beneficial compressive residual stress around the surface and sub-surface region of Mg-1Zn-0.5Sc alloy due to severe plastic deformation, which led to grain refinement through the twinning mechanism of the Mg alloy. Also, the dispersion of second-phase particles (β-ScZn) was observed while analysing the XRD profiles. Strain hardening, grain refinement, and precipitate strengthening have contributed to the structure and texture evolution, which enhanced the microhardness, tensile strength, ductility, and corrosion resistance of the Mg-1Zn-0.5Sc alloy. From in vitro studies, a low rate of corrosion in simulated body fluid and less cytotoxic behaviour were observed for the LSP-3 pass Mg-1Zn-0.5Sc alloy.

A drug-loaded composite coating to improve osteogenic and antibacterial properties of Zn-1Mg porous scaffolds as biodegradable bone implants.

Zinc (Zn) alloy porous scaffolds produced by additive manufacturing own customizable structures and biodegradable functions, having a great application potential for repairing bone defect. In this work, a hydroxyapatite (HA)/polydopamine (PDA) composite coating was constructed on the surface of Zn-1Mg porous scaffolds fabricated by laser powder bed fusion, and was loaded with a bioactive factor BMP2 and an antibacterial drug vancomycin. The microstructure, degradation behavior, biocompatibility, antibacterial performance and osteogenic activities were systematically investigated. Compared with as-built Zn-1Mg scaffolds, the rapid increase of Zn2+, which resulted to the deteriorated cell viability and osteogenic differentiation, was inhibited due to the physical barrier of the composite coating. In vitro cellular and bacterial assay indicated that the loaded BMP2 and vancomycin considerably enhanced the cytocompatibility and antibacterial performance. Significantly improved osteogenic and antibacterial functions were also observed according to in vivo implantation in the lateral femoral condyle of rats. The design, influence and mechanism of the composite coating were discussed accordingly. It was concluded that the additively manufactured Zn-1Mg porous scaffolds together with the composite coating could modulate biodegradable performance and contribute to effective promotion of bone recovery and antibacterial function.

Degradation behavior, cytotoxicity, hemolysis of partially unzipped carbon nanotubes/zinc composites as potential biodegradable bone implants

Zn with a suitable degradation rate is considered to be a promising candidate biodegradable implant materials. To enhance the mechanical properties of pure Zn and broaden its application in the field of short-term orthopedic surgery, a series of new Zn matrix composites with a high strength are developed by the addition of partially unzipped carbon nanotubes (PUCNTs), and the degradation behavior, cytotoxicity and hemolysis of new PUCNTs/Zn composites are investigated in this paper. The results show that the degradation rate of the PUCNTs/Zn composites with 0, 0.1, 0.2, 0.3 and 0.5 wt.% PUCNTs can meet the standard of clinical biomedical orthopedic implant materials. During cytotoxicity test, the density of living cells rapidly increases with increasing PUCNTs content, and the cell viability of MG-63 cells in the extract with different concentrations is higher than 90%, illustrating an excellent cytocompatibility. For the hematotoxicity assay, the hemolysis percentage of all PUCNTs/Zn composites samples is below the safety threshold of 5.0% for clinical application, exhibiting a good blood compatibility.

Extrusion-based 3D printing of biodegradable, osteogenic, paramagnetic, and porous FeMn-akermanite bone substitutes.

The development of biodegradable Fe-based bone implants has rapidly progressed in recent years. Most of the challenges encountered in developing such implants have been tackled individually or in combination using additive manufacturing technologies. Yet not all the challenges have been overcome. Herein, we present porous FeMn-akermanite composite scaffolds fabricated by extrusion-based 3D printing to address the unmet clinical needs associated with Fe-based biomaterials for bone regeneration, including low biodegradation rate, MRI-incompatibility, mechanical properties, and limited bioactivity. In this research, we developed inks containing Fe, 35 wt% Mn, and 20 or 30 vol% akermanite powder mixtures. 3D printing was optimized together with the debinding and sintering steps to obtain scaffolds with interconnected porosity of 69%. The Fe-matrix in the composites contained the γ-FeMn phase as well as nesosilicate phases. The former made the composites paramagnetic and, thus, MRI-friendly. The in vitro biodegradation rates of the composites with 20 and 30 vol% akermanite were respectively 0.24 and 0.27mm/y, falling within the ideal range of biodegradation rates for bone substitution. The yield strengths of the porous composites stayed within the range of the values of the trabecular bone, despite in vitro biodegradation for 28 d. All the composite scaffolds favored the adhesion, proliferation, and osteogenic differentiation of preosteoblasts, as revealed by Runx2 assay. Moreover, osteopontin was detected in the extracellular matrix of cells on the scaffolds. Altogether, these results demonstrate the remarkable potential of these composites in fulfilling the requirements of porous biodegradable bone substitutes, motivating future in vivo research. STATEMENT OF SIGNIFICANCE: We developed FeMn-akermanite composite scaffolds by taking advantage of the multi-material capacity of extrusion-based 3D printing. Our results demonstrated that the FeMn-akermanite scaffolds showed an exceptional performance in fulfilling all the requirements for bone substitution in vitro, i.e., a sufficient biodegradation rate, having mechanical properties in the range of trabecular bone even after 4 weeks biodegradation, paramagnetic, cytocompatible and most importantly osteogenic. Our results encourage further research on Fe-based bone implants in in vivo.

Study on 3D printing process of continuous polyglycolic acid fiber-reinforced polylactic acid degradable composites.

A continuous polyglycolic acid (PGA) fiber-reinforced polylactic acid (PLA) degradable composite was proposed for application in biodegradable load-bearing bone implant. The fused deposition modeling (FDM) process was used to fabricate composite specimens. The influences of the printing process parameters, such as layer thickness, printing spacing, printing speed, and filament feeding speed on the mechanical properties of the PGA fiber-reinforced PLA composites, were studied. The thermal properties of the PGA fiber and PLA matrix were investigated by using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The internal defects of the as-fabricated specimens were characterized by the micro-X- ray 3D imaging system. During the tensile experiment, a full-field strain measurement system was used to detect the strain map and analysis the fracture mode of the specimens. A digital microscope and field emission electron scanning microscopy were used to observe the interface bonding between fiber and matrix and fracture morphologies of the specimens. The experimental results showed that the tensile strength of specimens was related to their fiber content and porosity. The printing layer thickness and printing spacing had significant impacts on the fiber content. The printing speed did not affect the fiber content but had a slight effect on the tensile strength. Reducing the printing spacing and layer thickness could increase the fiber content. The tensile strength (along the fiber direction) of the specimen with 77.8% fiber content and 1.82% porosity was the highest, reaching 209.32 ± 8.37 MPa, which is higher than the tensile strength of the cortical bone and polyether ether ketone (PEEK), indicating that the continuous PGA fiber-reinforced PLA composite has great potential in the manufacture of biodegradable load-bearing bone implants.

Study of Microstructure and Corrosion Behavior of Cast Zn–Al–Mg Alloys

Zn-based alloys have found increasing interest as orthopedic biodegradable implantable materials, hence it was the aim of this work to investigate the microstructure and corrosion behavior of Zn–0.5Al–xMg cast alloys with different Mg additions in simulated body fluid (SBF). The cast samples were prepared using a simple stir casting method and the molten alloys were poured in a cast iron mold. The SEM results showed that adding Mg greatly influenced the microstructure of the Zn-based alloys where the degree of fineness of the microstructure increased with a rise in the Mg content. Moreover, polarization measurements revealed that the Zn–0.5Al–0.6Mg alloy attained the lowest degradation rate of 0.33 mm/year as compared to the other investigated alloys which complies the requirements of ideal corrosion rates for biodegradable bone implants. This corrosion rate helps the implantable metal alloy to last in the body until healing of the bone tissue proceeds. The fine structure and uniform distribution of Aluminum oxide and MgZn2 intermetallic phases along the grain boundaries were most likely the main factors in the superior corrosion stability of the Zn–0.5Al–0.6Mg alloy in SBF. However, higher concentrations of Mg (1 wt%) lowered the corrosion resistance of the Zn–Al–Mg alloy which was attributed to the accelerated galvanic corrosion between Zn and Mg2 Zn11 phases and the inhomogeneous distribution of corrosion products on the alloy surface due to the increased grain size and the coarse structure of the Zn alloy.

Exploring the Usability of α-MSH-SM-Liposome as an Imaging Agent to Study Biodegradable Bone Implants In Vivo.

Novel biodegradable metal alloys are increasingly used as implant materials. The implantation can be accompanied by an inflammatory response to a foreign object. For studying inflammation in the implantation area, non-invasive imaging methods are needed. In vivo imaging for the implanted area and its surroundings will provide beneficiary information to understand implant-related inflammation and help to monitor it. Therefore, inflammation-sensitive fluorescent liposomes in rats were tested in the presence of an implant to evaluate their usability in studying inflammation. The sphingomyelin-containing liposomes carrying alpha-melanocyte-stimulating hormone (α-MSH)-peptide were tested in a rat bone implant model. The liposome interaction with implant material (Mg-10Gd) was analyzed with Mg-based implant material (Mg-10Gd) in vitro. The liposome uptake process was studied in the bone-marrow-derived macrophages in vitro. Finally, this liposomal tracer was tested in vivo. It was found that α-MSH coupled sphingomyelin-containing liposomes and the Mg-10Gd implant did not have any disturbing influence on each other. The clearance of liposomes was observed in the presence of an inert and biodegradable implant. The degradable Mg-10Gd was used as an alloy example; however, the presented imaging system offers a new possible use of α-MSH-SM-liposomes as tools for investigating implant responses.

Corrosion processes of sintered materials based on Fe

All currently used metal-based implants have the disadvantage of often requiring secondary surgery to remove the implant. This is why there is a lot of research into biodegradable bone implants these days. Biodegradable iron-based alloys are potential candidates for use as materials for temporary implants. This work deals with the current topic of Fe-based biodegradable sintered materials and their corrosion. These materials are suitable for applications where gradual decomposition is required. Sintered materials based on Fe-Mg are investigated in this work. The manufactured samples were immersed in NaCl solution and simulated body fluid – SBF. Subsequently, changes in corrosion potential and current, pH, conductivity and observations under the microscope were regularly analysed.

Direct ink writing of porous Fe-HA metal-matrix composites (MMCs) with independently adjustable porosity and degradation rate for bone implant applications

The porosity and degradation rate are critical properties of biodegradable bone implants, as they facilitate the regeneration of bone tissues and ensure a gradual load transfer. Herein, porous iron-hydroxyapatite (Fe-HA) metal-matrix composites (MMCs) with independently adjustable porosity and degradation rate are fabricated through a 3D printing technique, i.e., direct ink writing (DIW). HA micro powders exhibit a significant acceleration effect on the degradation rate, which act as a variable that is independent of the porosity to regulate the degradation rate. The mass losses of Fe-HA MMCs with the porosities of 30%, 50%, and 70% after 21d in-vitro immersion increased by 26%, 38%, and 93%, respectively, with the rising of HA content from 0 to 7.5 wt%. The novel porous Fe-HA MMCs have an adjustable and wide porosity-degradation rate range, yielding great potential to match with varied porosity and regeneration rate among various bones of different people.