Alloying design of biodegradable zinc as promising bone implants for load-bearing applications.
Ontology highlight
ABSTRACT:
SUBMITTER: Yang H
PROVIDER: S-EPMC6972918 | biostudies-literature |
REPOSITORIES: biostudies-literature
Similar Datasets
Project description:A biodegradable scaffold with tissue ingrowth and load-bearing capabilities is required to accelerate the healing of bone defects. However, it is difficult to maintain the mechanical properties as well as biodegradability and porosity (necessary for bone ingrowth) at the same time. Therefore, in the present study, polycaprolactone (PCL) and poly(lactic-co-glycolic acid) (PLGA5050) were mixed in varying ratio and incorporated with 20 wt.% ?TCP. The mixture was shaped under pressure into originally non-porous cylindrical constructs. It is envisioned that the fabricated constructs will develop porosity with the time-dependent biodegradation of the polymer blend. The mechanical properties will be sustained since the decrease in mechanical properties associated with the dissolution of the PLGA and the formation of the porous structure will be compensated with the new bone formation and ingrowth. To prove the hypothesis, we have systematically studied the effects of samples composition on the time-dependent dissolution behavior, pore formation, and mechanical properties of the engineered samples, in vitro. The highest initial (of as-prepared samples) values of the yield strength (0.021±0.002 GPa) and the Young's modulus (0.829±0.096 GPa) were exhibited by the samples containing 75 wt.% of PLGA. Increase of the PLGA concentration from 25 wt.% to 75 wt.% increased the rate of biodegradation by a factor of 3 upon 2 weeks in phosphate buffered saline (1× PBS). The overall porosity and the pore sizes increased with the dissolution time indicating that the formation of in-situ pores can indeed enable the migration of cells followed by vascularization and bone growth.
| S-EPMC6855254 | biostudies-literature
Project description:Magnesium (Mg) alloys are being investigated as a biodegradable metallic biomaterial because of their mechanical property profile, which is similar to the human bone. However, implants based on Mg alloys are corroded quickly in the body before the bone fracture is fully healed. Therefore, we aimed to reduce the corrosion rate of Mg using a double protective layer. We used a magnesium-aluminum-zinc alloy (AZ91) and treated its surface with micro-arc oxidation (MAO) technique to first form an intermediate layer. Next, a bioceramic nanocomposite composed of diopside, bredigite, and fluoridated hydroxyapatite (FHA) was coated on the surface of MAO treated AZ91 using the electrophoretic deposition (EPD) technique. Our in vivo results showed a significant enhancement in the bioactivity of the nanocomposite coated AZ91 implant compared to the uncoated control implant. Implantation of the uncoated AZ91 caused a significant release of hydrogen bubbles around the implant, which was reduced when the nanocomposite coated implants were used. Using histology, this reduction in the corrosion rate of the coated implants resulted in an improved new bone formation and reduced inflammation in the interface of the implants and the surrounding tissue. Hence, our strategy using a MAO/EPD of a bioceramic nanocomposite coating (i.e., diopside-bredigite-FHA) can significantly reduce the corrosion rate and improve the bioactivity of the biodegradable AZ91 Mg implant.
| S-EPMC7143302 | biostudies-literature
Project description:Bone defect repair is a complicated clinical problem, particularly when the defect is relatively large and the bone is unable to repair itself. Magnesium and its alloys have been introduced as versatile biomaterials to repair bone defects because of their excellent biocompatibility, osteoconductivity, bone-mimicking biomechanical features, and non-toxic and biodegradable properties. Therefore, magnesium alloys have become a popular research topic in the field of implants to treat critical bone defects. This review explores the popular Mg alloy research topics in the field of bone defects. Bibliometric analyses demonstrate that the degradation control and mechanical properties of Mg alloys are the main research focus for the treatment of bone defects. Furthermore, the additive manufacturing (AM) of Mg alloys is a promising approach for treating bone defects using implants with customized structures and functions. This work reviews the state of research on AM-Mg alloys and the current challenges in the field, mainly from the two aspects of controlling the degradation rate and the fabrication of excellent mechanical properties. First, the advantages, current progress, and challenges of the AM of Mg alloys for further application are discussed. The main mechanisms that lead to the rapid degradation of AM-Mg are then highlighted. Next, the typical methods and processing parameters of laser powder bed fusion fabrication on the degradation characteristics of Mg alloys are reviewed. The following section discusses how the above factors affect the mechanical properties of AM-Mg and the recent research progress. Finally, the current status of research on AM-Mg for bone defects is summarized, and some research directions for AM-Mg to drive the application of clinical orthopedic implants are suggested.
| S-EPMC9745192 | biostudies-literature
Project description:Despite the tremendous technological advances that metal additive manufacturing (AM) has made in the last decades, there are still some major concerns guaranteeing its massive industrial application in the biomedical field. Indeed, some main limitations arise in dealing with their biological properties, specifically in terms of osseointegration. Morphological accuracy of sub-unital elements along with the printing resolution are major constraints in the design workspace of a lattice, hindering the possibility of manufacturing structures optimized for proper osteointegration. To overcome these issues, the authors developed a new hybrid multifunctional composite scaffold consisting of an AM Ti6Al4V lattice structure and a silk fibroin/gelatin foam. The composite was realized by combining laser powder bed fusion (L-PBF) of simple cubic lattice structures with foaming techniques. A combined process of foaming and electrodeposition has been also evaluated. The multifunctional scaffolds were characterized to evaluate their pore size, morphology, and distribution as well as their adhesion and behavior at the metal-polymer interface. Pull-out tests in dry and hydrated conditions were employed for the mechanical characterization. Additionally, a cytotoxicity assessment was performed to preliminarily evaluate their potential application in the biomedical field as load-bearing next-generation medical devices.
| S-EPMC9458142 | biostudies-literature
Project description:A novel biodegradable metal system, ZnLiCa ternary alloys, were systematically investigated both in vitro and in vivo. The ultimate tensile strength (UTS) of Zn0.8Li0.1Ca alloy reached 567.60 ± 9.56 MPa, which is comparable to pure Ti, one of the most common material used in orthopedics. The elongation of Zn0.8Li0.1Ca is 27.82 ± 18.35%, which is the highest among the ZnLiCa alloys. The in vitro degradation rate of Zn0.8Li0.1Ca alloy in simulated body fluid (SBF) showed significant acceleration than that of pure Zn. CCK-8 tests and hemocompatibility tests manifested that ZnLiCa alloys exhibit good biocompatibility. Real-time PCR showed that Zn0.8Li0.1Ca alloy successfully stimulated the expressions of osteogenesis-related genes (ALP, COL-1, OCN and Runx-2), especially the OCN. An in vivo implantation was conducted in the radius of New Zealand rabbits for 24 weeks, aiming to treat the bone defects. The Micro-CT and histological evaluations proved that the regeneration of bone defect was faster within the Zn0.8Li0.1Ca alloy scaffold than the pure Ti scaffold. Zn0.8Li0.1Ca alloy showed great potential to be applied in orthopedics, especially in the load-bearing sites.
| S-EPMC8085902 | biostudies-literature
Project description:This review discusses and summarizes the recent developments and advances in the use of biodegradable materials for bone repair purposes. The choice between using degradable and non-degradable devices for orthopedic and maxillofacial applications must be carefully weighed. Traditional biodegradable devices for osteosynthesis have been successful in low or mild load bearing applications. However, continuing research and recent developments in the field of material science has resulted in development of biomaterials with improved strength and mechanical properties. For this purpose, biodegradable materials, including polymers, ceramics and magnesium alloys have attracted much attention for osteologic repair and applications. The next generation of biodegradable materials would benefit from recent knowledge gained regarding cell material interactions, with better control of interfacing between the material and the surrounding bone tissue. The next generations of biodegradable materials for bone repair and regeneration applications require better control of interfacing between the material and the surrounding bone tissue. Also, the mechanical properties and degradation/resorption profiles of these materials require further improvement to broaden their use and achieve better clinical results.
| S-EPMC5512653 | biostudies-other
Project description:Biodegradable arterial implants based on zinc have been found to suppress neointimal hyperplasia, suggesting that biodegradable materials containing zinc may be used to construct vascular implants with a reduced rate of restenosis. However, the molecular mechanism has remained unclear. In this report, we show that zinc-containing materials can be used to prevent neointimal formation when implanted into the rat aorta. Indeed, neointimal cells were significantly more TUNEL positive and alpha-actin negative at the interface of biodegradable zinc vs. biostable platinum implants, in association with greater caspase-3 activity. Although zinc stimulated extensive neointimal smooth muscle cell (SMC) death, macrophage and proinflammatory markers CD68 and iNOS were not increased in neointimal tissue relative to biostable platinum control implants. Using arterial explants, ionic zinc was confirmed to promote SMC apoptosis by activating the caspase apoptotic signaling pathway. These observations suggest that zinc-containing materials can be used to construct vascular implants such as stents with reduced neointimal hyperplasia.
| S-EPMC7962177 | biostudies-literature
Project description:Cobalt-chromium-molybdenum (CoCrMo) alloys are widely used in load-bearing implants; specifically, in hip, knee, and spinal applications due to their excellent wear resistance. However, due to in vivo corrosion and mechanically assisted corrosion, metal ion release occurs and accounts for poor biocompatibility. Therefore, a significant interest to find an alternative to CoCrMo alloy exists. In the present work we hypothesize that calcium phosphate (CaP) will behave as a solid lubricant in CoCrMo alloy under tribological testing, thereby minimizing wear and metal ion release concerns associated with CoCrMo alloy. CoCrMo-CaP composite coatings were processed using laser engineered net shaping (LENS™) system. After LENS™ processing, CoCrMo alloy was subjected to laser surface melting (LSM) using the same LENS™ set-up. Samples were investigated for microstructural features, phase identification, and biocompatibility. It was found that LSM treated CoCrMo improved wear resistance by 5 times. CoCrMo-CaP composites displayed the formation of a phosphorus-based tribofilm. In vitro cell-material interactions study showed no cytotoxic effect. Sprague-Dawley rat and rabbit in vivo study displayed increased osteoid formation for CoCrMo-CaP composites, up to 2 wt.% CaP. Our results show that careful surface modification treatments can simultaneously improve wear resistance and in vivo biocompatibility of CoCrMo alloy, which can correlate to a reduction of metal ion release in vivo.
| S-EPMC6656377 | biostudies-literature
Project description:The aerospace and automotive industries find that relying solely on the intrinsic resistance of alloys is inadequate to safeguard aircraft and automotive structural components from harsh environmental conditions. While it is difficult to attribute accidents exclusively to coating failure due to the involvement of multiple factors, there are instances where defects in the coating initiate a wear or degradation process, leading to premature and unplanned structural failures. Metallic coatings have been introduced to protect the aircraft mainly from wear due to the extreme temperatures and moisture exposure during their service life. Bare metallic coatings have a limited lifespan and need to be replaced frequently. Herein, the strength and wear resistance of zinc (Zn) coating is enhanced using varying concentrations of diamond particles as an additive in the Zn matrix (Zn-D). The dispersion strengthening mechanism is attributed to the high hardness (70 HRC), and reduced friction-of-coefficient (0.21) and dissipation energy (4.6 × 10-4 J) of electrodeposited Zn-D7.5 (7.5 g l-1 of diamond concentration) composite coating. Moreover, enhanced wear resistance with minimum wear volume (1.12 × 10-3 mm3) and wear rate (1.25 × 10-3 mm3 N-1 m-1) of the Zn-D7.5 composite coating resulted in perfect blending of diamond with Zn. The improved hardness and wear resistance for Zn-D7.5 (optimum 7.5 g l-1 diamond concentration) is due to the steadiness between well-dispersed diamonds in Zn and enrichment in load-bearing ability due to the incorporation of diamond particles. Electronic structure calculations on the zinc-diamond composite models (two configurations adopted) have been performed using the density functional theory (DFT) approach, and the in silico studies appeared to facilitate meaningful and evocative outcomes. Zn-doped diamond (C10@Zn) without hydrogen (H) atoms (binding energy: 418 kcal mol-1, i.e. showing an endothermic reaction and thermodynamically not favourable) was detected to be more stable than the Zn-doped diamond (C10H16@Zn) consisting of hydrogen (H) atoms (binding energy: -33.3 kcal mol-1, i.e. showing an exothermic reaction and thermodynamically preferable). Thus, a composite coating of zinc and diamond can be a suitable candidate for the aerospace and automotive industries.
| S-EPMC10825905 | biostudies-literature
Project description:Highly accurate segmentation of large 3D volumes is a demanding task. Challenging applications like the segmentation of synchrotron radiation microtomograms (SRμCT) at high-resolution, which suffer from low contrast, high spatial variability and measurement artifacts, readily exceed the capacities of conventional segmentation methods, including the manual segmentation by human experts. The quantitative characterization of the osseointegration and spatio-temporal biodegradation process of bone implants requires reliable, and very precise segmentation. We investigated the scaling of 2D U-net for high resolution grayscale volumes by three crucial model hyper-parameters (i.e., the model width, depth, and input size). To leverage the 3D information of high-resolution SRμCT, common three axes prediction fusing is extended, investigating the effect of adding more than three axes prediction. In a systematic evaluation we compare the performance of scaling the U-net by intersection over union (IoU) and quantitative measurements of osseointegration and degradation parameters. Overall, we observe that a compound scaling of the U-net and multi-axes prediction fusing with soft voting yields the highest IoU for the class "degradation layer". Finally, the quantitative analysis showed that the parameters calculated with model segmentation deviated less from the high quality results than those obtained by a semi-automatic segmentation method.
| S-EPMC8688506 | biostudies-literature