Metallic lattice structures can be fabricated by selective laser melting (SLM) with purposefully designed pores and controlled pore sizes that can bio mimic the natural bone, providing adequate ...mechanical and biological support for the patients. Strut-based structures, like Cubic, Octet; and sheet-based structures, like triply periodic minimal surface (TPMS) gyroid, have been studied extensively in the past. However, it lacks enough comparative study on the mechanical properties and cytotoxicity among these structures. Therefore, Cubic, Octet, and TPMS gyroid of Stainless steel 316 L (SS316L) are designed, manufactured, and characterized at 40/50/60% relative densities in this study. Moreover, the flowability, density characteristics, and cytotoxicity of SS316L powder are validated to ascertain its suitability for 3D printing and implant application. Based on refining the Gibson-Ashby model, it is possible to predict or design the mechanical properties via adjusting the relative densities. The results indicate these structures demonstrated appropriate Young's modulus and outstanding biocompatibility.
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Bone defects and diseases are devastating, and can lead to severe functional deficits or even permanent disability. Nevertheless, orthopedic implants and scaffolds can facilitate the growth of ...incipient bone and help us to treat bone defects and diseases. Currently, a wide range of biomaterials with distinct biocompatibility, biodegradability, porosity, and mechanical strength is used in bone‐related research. However, most orthopedic implants and scaffolds have certain limitations and diverse complications, such as limited corrosion resistance, low cell proliferation, and bacterial adhesion. With recent advancements in materials science and nanotechnology, metallic and metallic oxide nanoparticles have become the subject of significant interest as they offer an ample variety of options to resolve the existing problems in the orthopedic industry. More importantly, these nanoparticles possess unique physicochemical and mechanical properties not found in conventional materials, and can be incorporated into orthopedic implants and scaffolds to enhance their antimicrobial ability, bioactive molecular delivery, mechanical strength, osteointegration, and cell labeling and imaging. However, many metallic and metallic oxide nanoparticles can also be toxic to nearby cells and tissues. This review article will discuss the applications and functions of metallic and metallic oxide nanoparticles in orthopedic implants and bone tissue engineering.
Different materials have been studied for decades for biomedical implants based on their various biocompatibility and mechanical properties to suit individual requirements. Among the various ...biomaterials for bone implants, Ti6Al4V and SS316L are two popular metallic materials due to many advantages, such as corrosion resistance, high strength-to-weight ratio, biocompatibility, lightweight, durability, and osseointegration properties. However, Young’s modulus of Ti6Al4V (110-120 GPa) and SS316L (190-210 GPa) is much higher than Young’s modulus of natural human bone (4-30 GPa), which may lead to stress shielding effect, i.e., weakening adjacent bones and tissues. As a result, it is crucial to construct the implant with mechanical qualities that are compatible with the patient's natural bone. With the advent of 3D printing, it is now possible to construct porous structures with optimal mechanical properties by altering relative densities to meet specific requirements. Through mechanical characterization and validation, updated formulas for Young's modulus and yield strength versus relative density can be derived for specific porous structures based on the generic Gibson-Ashby model. Moreover, due to the daily wear and tear, the debris or particles may be released to the patient body, which may lead to inflammation and other syndromes, and even revisionary surgeries. Thus, it is vital to assess the bone implant material's toxicity. Specific countermeasures must be taken to avoid potential toxicity and other side effects. The cytotoxicity of Ti/SS316L/Mg particles was thoroughly investigated in human osteosarcoma (SAOS2 cells). Even at high concentrations, SS316L particles exhibit minimal cytotoxicity to cells. However, Ti particles are toxic to cells at various dosages and time intervals, whereas Mg particles are beneficial to cell viability at low concentrations and are even more toxic than Ti particles at high concentrations. Given that Ti is still the most often used material for implant applications, a hybrid implant composed of both Ti and Mg can help mitigate the detrimental effects of titanium particles. To further investigate this phenomenon, different amounts of Ti particles, Mg particles, and Ti-Mg particles were added to SAOS2 cells, and cell viability was monitored at 2/3/5 days. Additional biological investigations were conducted to determine the effect of Ti and Mg particles on SAOS2 cells.Additionally, due to the beneficial effects of Mg ions and the excellent properties of Ti, Mg was injected into porous Ti structures (pore-by-process) to produce long-lasting hybrid bone implants. Ti-Mg composites were shown to be more biocompatible than porous Ti structures alone. The biodegradable Mg component can be tailored to disintegrate slowly, so mitigating the negative consequences of Ti debris. This Ti-Mg composite material offers a great deal of potential for future orthopedic implant applications.Moreover, three different lattice structures (pore-by-design) made of SS316L were investigated as well. Based on the Gibson-Ashby model, the theoretical and actual Young’s modulus/yield strength were compared. A modified Gibson-Ashby model was proposed to make more accurate predictions based on the existing lattice structures and process parameters.Following that, in addition to the conventional biomaterials, a unique Fe-based metallic glass (MG) was created explicitly. The bulk Fe-based MG was synthesized using Selective Laser Melting (SLM). In comparison to SS316L, Fe-based MG has superior mechanical qualities, adequate corrosion resistance, and a high degree of biocompatibility. The hardness and elastic modulus of the produced Fe-based MG can be adjusted during 3D printing by altering the laser power and scanning speed. Further research can be conducted further to enhance the mechanical characteristics and biocompatibility of Fe-based MG to meet individual needs. SLM-produced Fe-based MG has significant potential for enhancing bone implant applications and other biological applications.In summary, numerous ways have been investigated for developing bone implants with predictable mechanical properties, less adverse effects, and increased biocompatibility. These findings will extend the life of bone implants and minimize the adverse effects of high-strength biocompatible materials, thereby improving patients' quality of life.
Purpose
To manufacture and test 3D printed novel design titanium spine rods with lower flexural modulus and stiffness compared to standard solid titanium rods for use in metastatic spine tumour ...surgery (MSTS) and osteoporosis.
Methods
Novel design titanium spine rods were designed and 3D printed. Three-point bending test was performed to assess mechanical performance of rods, while a French bender was used to assess intraoperative rod contourability. Furthermore, 3D printed spine rods were tested for CT & MR imaging compatibility using phantom setup.
Results
Different spine rod designs generated includes shell, voronoi, gyroid, diamond, weaire-phelan, kelvin, and star. Tests showed 3D printed rods had lower flexural modulus with reduction ranging from 2 to 25% versus standard rod. Shell rods exhibited highest reduction in flexural modulus of 25% (~ 77.4 GPa) and star rod exhibited lowest reduction in flexural modulus of 2% (100.8GPa). 3D printed rod showed reduction in stiffness ranging from 40 to 59%. Shell rod displayed highest reduction in stiffness of 59% (179.9 N/mm) and gyroid had least reduction in stiffness of 40% (~ 259.2 N/mm). Rod bending test showed that except gyroid, other rod designs demonstrated lesser bending difficulty versus standard rod. All 3D printed rods demonstrated improved CT/MR imaging compatibility with reduced artefacts versus standard rod.
Conclusion
By utilising novel design approach, we successfully generated a spine rod design portfolio with lower flexural modulus/stiffness profile and better CT/MR imaging compatibility for potential use in MSTS/other conditions such as osteoporosis. Thus, exploration of new rod designs in surgical application could enhance treatment outcome and improve quality of life for patients.
Purpose
To develop a novel 3D printable polyether ether ketone (PEEK)-hydroxyapatite (HA)-magnesium orthosilicate (Mg
2
SiO
4
) composite material with enhanced properties for potential use in ...tumour, osteoporosis and other spinal conditions. We aim to evaluate biocompatibility and imaging compatibility of the material.
Methods
Materials were prepared in three different compositions, namely composite A: 75 weight % PEEK, 20 weight % HA, 5 weight % Mg
2
SiO
4
; composite B: 70 weight% PEEK, 25 weight % HA, 5 weight % Mg
2
SiO
4
; and composite C: 65 weight % PEEK, 30 weight % HA, 5 weight % Mg
2
SiO
4
. The materials were processed to obtain 3D printable filament. Biomechanical properties were analysed as per ASTM standards and biocompatibility of the novel material was evaluated using indirect and direct cell cytotoxicity tests. Cell viability of the novel material was compared to PEEK and PEEK-HA materials. The novel material was used to 3D print a standard spine cage. Furthermore, the CT and MR imaging compatibility of the novel material cage vs PEEK and PEEK-HA cages were evaluated using a phantom setup.
Results
Composite A resulted in optimal material processing to obtain a 3D printable filament, while composite B and C resulted in non-optimal processing. Composite A enhanced cell viability up to ~ 20% compared to PEEK and PEEK-HA materials. Composite A cage generated minimal/no artefacts on CT and MR imaging and the images were comparable to that of PEEK and PEEK-HA cages.
Conclusion
Composite A demonstrated superior bioactivity vs PEEK and PEEK-HA materials and comparable imaging compatibility vs PEEK and PEEK-HA. Therefore, our material displays an excellent potential to manufacture spine implants with enhanced mechanical and bioactive property.
The complex and hierarchical structure with high vascularization of human bone limits the applications of traditional bone tissue engineering, especially in large bone defects. Progress in ...nanotechnology and 3D printing has opened new opportunities for bone tissue engineering. Nanoparticles possess unique size-dependent physicochemical and mechanical properties, such as bone scaffold enhancement, drug delivery ability, and bioimaging ability, that are rarely detected in bulk components. Nanoparticles with these features have enabled us to create multi-functional bone scaffolds within a single system. At the same time, 3D printing can make the scaffolds with fully customizable designs. These nanoparticle-embedded 3D printed scaffolds used in bone tissue engineering have tremendous potential to enhance bone regeneration and healing. The previous review paper covered the functions and applications of metallic and metal oxide nanoparticles in bone tissue engineering. This review paper aims to cover the most recent bone tissue engineering applications based on different ceramic nanoparticles in 3D printed scaffolds. This paper also summarizes the capabilities and limitations of the multi-functional ceramic nanoparticles, and potential future improvement solutions.
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Bioelectricity has been a fundamental property of all living organisms. With electrical stimulation, living cells can interact with their microenvironments, which makes electrical stimulation highly ...beneficial for various biomedical applications. However, traditional electrical stimulation mainly relies on bulky and complex equipment, which may not be ideal due to the restriction of movement, limited battery lifetime, uncomfortable wearing, and potential unfriendly to the environment. The advent of triboelectric nanogenerators (TENGs) has helped to resolve the existing limitations. TENGs are effective energy harvesting systems that use a mix of triboelectrification and electrostatic induction to create electrical energy from kinetic energy. TENGs deliver self‐powered electrical stimulation to bone cells for functional regulation or bone regeneration, serve as sensors to detect biological signals or movements, or act as a power source for other biomedical devices. TENGs can be employed in various applications, including enhancing bone regeneration, providing sensing function, slowing bone aging, and curing implant‐related infections. The recent applications of TENGs in bone tissue engineering are reviewed, and the drawbacks of the TENGs are discussed. Finally, the existing challenges and future roadmap for developing TENGs are presented.
Triboelectric nanogenerators (TENGs) are effective and cutting‐edge energy harvesting systems that can deliver self‐powered electrical stimulation to bone cells for functional regulation or bone regeneration, serve as sensors to detect biological signals or movements, and act as a power source for other biomedical devices. Besides bone tissue engineering, TENGs also have great potential in other biomedical applications.
To develop a novel 3D printable polyether ether ketone (PEEK)-hydroxyapatite (HA)-magnesium orthosilicate (Mg
SiO
) composite material with enhanced properties for potential use in tumour, ...osteoporosis and other spinal conditions. We aim to evaluate biocompatibility and imaging compatibility of the material.
Materials were prepared in three different compositions, namely composite A: 75 weight % PEEK, 20 weight % HA, 5 weight % Mg
SiO
; composite B: 70 weight% PEEK, 25 weight % HA, 5 weight % Mg
SiO
; and composite C: 65 weight % PEEK, 30 weight % HA, 5 weight % Mg
SiO
. The materials were processed to obtain 3D printable filament. Biomechanical properties were analysed as per ASTM standards and biocompatibility of the novel material was evaluated using indirect and direct cell cytotoxicity tests. Cell viability of the novel material was compared to PEEK and PEEK-HA materials. The novel material was used to 3D print a standard spine cage. Furthermore, the CT and MR imaging compatibility of the novel material cage vs PEEK and PEEK-HA cages were evaluated using a phantom setup.
Composite A resulted in optimal material processing to obtain a 3D printable filament, while composite B and C resulted in non-optimal processing. Composite A enhanced cell viability up to ~ 20% compared to PEEK and PEEK-HA materials. Composite A cage generated minimal/no artefacts on CT and MR imaging and the images were comparable to that of PEEK and PEEK-HA cages.
Composite A demonstrated superior bioactivity vs PEEK and PEEK-HA materials and comparable imaging compatibility vs PEEK and PEEK-HA. Therefore, our material displays an excellent potential to manufacture spine implants with enhanced mechanical and bioactive property.
•As compared to 316 L SS, Fe-based BMG exhibits optimal mechanical properties, adequate corrosion resistance, and excellent biocompatibility.•regardless of the various processing parameters, nearly ...fully amorphous structures specimen can be produced by SLM.•At the same energy density, the hardness and elastic modulus can be varied by adjusting laser power and scanning speed.•Lower processing parameters (at the same energy) can generate Fe-based BMG with a rougher surface, which can release more beneficial ions for better biocompatibility.
The unique properties of bulk metallic glass (BMG) render it an excellent material for bone-implant applications. BMG samples are difficult to produce directly because of the critical cooling rate of molding. Advancements in additive manufacturing technologies, such as selective laser melting (SLM), have enabled the development of BMG. The successful production of materials via SLM relies significantly on the processing parameters; meanwhile, the overall energy density affects the crystallization and, thus, the final properties. Therefore, to further determine the effects of the processing parameters, SLM is performed in this study to print Fe-based BMG with different properties three dimensionally using selected processing parameters but a constant energy density. The printed amorphous Fe-based BMG outperforms the typical 316 L stainless steel (316 L SS) in terms of mechanical properties and corrosion resistance. Moreover, observations from nanoindentation tests indicate that the hardness and elastic modulus of the Fe-based BMG can be customized explicitly by adjusting the SLM processing parameters. Indirect cytotoxicity results show that the Fe-based BMG can enhance the viability of SAOS2 cells, as compared with 316 L SS. These intriguing results show that Fe-based BMG should be investigated further for orthopedic implant applications.
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Hybrid implants combine both Titanium (Ti) and Magnesium (Mg) are prevalent nowadays. The long-term implications of Ti and Mg implants within the human body are not yet fully understood. Many implant ...failure cases due to inflammation, allergic responses, and aspect loosening have been reported frequently. Particles generated through daily wear and tear of implants may worsen the situation by causing acute complications. An in-depth understanding of the behavior of metal particles with human osteoblasts is necessary. In this study, a novel and systematic attempt was made to understand the effects of different concentrations of Ti and Mg particles to the osteoblastic SAOS2 cell: toxicity, alterations to mitochondria, and changes to the specific gene and protein expression. Ti particles were found toxic to SAOS2 cells at different dosages, while Mg particles at lower concentrations could improve cell viability. To understand this phenomenon better, we have measured cellular reactive oxygen species (ROS) production and cell apoptosis & necrosis percentage. We also have checked the mitochondrial structure with transmission electron microscope (TEM), and mitochondrial function using Tetramethyl rhodamine, ethyl ester staining (TMRE). NDUFB6, SDHC, and ATP5F1 were the essential mitochondrial genes involved in the ROS production and ATP production. Immunocytochemistry (ICC) and real-time polymerase chain reaction (qPCR) were implemented to check the regulations of these related genes.
