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Bone mineral density (BMD) before and after sintering and the BMD ratio (the results after sintering/the results before sintering) with respect to the PMMA addition amount; the paired t-test for difference between BMD before sintering and BMD after sintering was carried out and p < 0.001.
Source publication
Porous hydroxyapatite (HA) artificial bone scaffolds were prepared via the freeze-gel casting process in order to improve their mechanical strengths. As a porogen, various volumes of poly (methyl methacrylate) (PMMA) powders were added to obtain high porosity, such as in cancellous bone. After fabrication, the porous and mechanical properties of th...
Context in source publication
Context 1
... as the amount of PMMA increased, it was observed that the difference in BMDs before and after sintering increased. Specifically, after sintering, HA75 became approximately 2.5 times denser than before sintering, whereas HA0 became approximately doubly denser (Figure 4). . Bone mineral density (BMD) before and after sintering and the BMD ratio (the results after sintering/the results before sintering) with respect to the PMMA addition amount; the paired t-test for difference between BMD before sintering and BMD after sintering was carried out and p < 0.001. ...
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Citations
... Since both types of fabricated scaffolds were composed of the same core material and had the same thickness, the distinction in mechanical characteristics of GS and HS is attributed to the morphological differences, such as pore sizes, and density of layers. Thus, layers with small and intermediate pores in the GS contribute to an increase in scaffold stiffness [19,78]. ...
Macroporous hydrogel scaffolds are widely used in tissue engineering to promote cell growth and proliferation. Aiming to enhance cell seeding efficiency and facilitate the osteodifferentiation of mesenchymal stem cells, this study demonstrates the fabrication of pore gradient biodegradable hydrogel scaffolds inspired by natural bone structures for bone tissue engineering applications. The scaffolds were fabricated via extrusion-based 3D printing, using sequential deposition of three customized Gelatin/Oxidized Alginate - based inks with subsequent cryogenic crosslinking for permanent structure fixation. The resulting constructs were characterized and featured a continuous gradient morphology with pore sizes ranging from 10 to 300 µm. The gradient scaffolds exhibited improved mechanical stability, with a compression resistance of 149 kPa, as opposed to the non-gradient scaffold’s 116 kPa at 70% strain, and a sustained degradation rate with only a 10% loss of its initial weight within three weeks. Gradient scaffolds demonstrated a doubling of cell seeding efficiency to 47% with dense and homogeneously distributed cellular layers, as evidenced by confocal and electron microscopy. Furthermore, the gradient scaffolds demonstrated superior osteodifferentiation, with significantly higher ALP and DMP1 production and enhanced extracellular matrix mineralization compared to gradientless macroporous scaffolds. This study provides insights into the design of macroporous scaffolds and emphasizes the advantages of pore gradient over homogeneous gradientless morphologies.
... For the fabrication of bone scaffolds, a high porosity in the range of 40-90% is recommended [21][22][23]. However, a study conducted by Gregor et al. [24] found that scaffolds with 30-50% porosity demonstrated cell attachment and proliferation comparable to scaffolds with 90% porosity. ...
... While earlier studies advocate for higher porosity in bone scaffold fabrication [21][22][23], the current study indicates that even scaffolds with porosities as low as 16.9-20.91% can demonstrate favorable mechanical properties. ...
Utilising finite element analyses and experimental testing, this study investigates the influence of scaffold porosity on mechanical behaviour and evaluates the potential of polylactic acid (PLA) and polyvinylidine fluoride (PVDF) as bone substitute materials. Scaffold geometries were devised using design parameters adapted from extant literature and then generated using computer-aided engineering tools. Methodical variations in strand thickness were applied, maintaining other design criteria constant for robust analysis. Results, derived under varied loading conditions, suggest that scaffold mechanical properties are influenced significantly by geometry, strand diameter and porosity. Cubic scaffolds exhibited marked strength. Structures with reduced porosity demonstrated heightened mechanical characteristics, while facilitating bone cell proliferation. For a comparative context, PVDF scaffolds were benchmarked against human femur bone properties, revealing a mechanical behaviour alignment, particularly in their Young’s modulus.
... 20 Scaffolds used as a bone replacement need a 60% to 90% porosity with an average pore size of 150 µm and compressive strength comparable to the cortical bone of 100MPa to 230 MPa or trabecular bone of 1MPa to 12MPa. [21][22][23] The compressive strength of a scaffold material is mainly studied to determine its maximum load-bearing capacity. 24 The ideal scaffold must have good mechanical properties, including compressive strength to withstand pressure from tissue and maintain space for cell and new bone growth. ...
... [35][36][37][38] Thus, it is vital for a bone scaffold to have identical mechanical properties as trabecular bone. 23 In the results of previous studies, the trabecular bone mechanical properties have a value of compressive strength of at least 1 MPa. 39 A study by Waletzko-Hellwig showed that the compressive strength of trabecular bone is 2 to 48 MPa. ...
Background: One of the main components in tissue engineering is the scaffold, which may serve as a medium to support cell and tissue growth. Scaffolds must have good compressive strength and controlled biodegradability to show biological activities while treating bone defects. This study uses Chitosan-gelatin (C–G) with good flexibility and elasticity and high-strength carbonate hydroxyapatite (CHA), which may be the ideal scaffold for tissue engineering. Purpose: To analyze the compressive strength and static biodegradation rate within various ratios of C–G and CHA (C–G:CHA) scaffold as a requirement for bone tissue engineering. Methods: The scaffold is synthesized from C–G:CHA with three ratio variations, which are 40:60, 30:70, and 20:80 (weight for weight [w/w]), made with a freeze-drying method. The compressive strengths are then tested. The biodegradation rate is tested by soaking the scaffold in simulated body fluid for 1, 3, 7, 14, and 21 days. Data are analyzed with a one-way ANOVA parametric test. Results: The compressive strength of each ratio of C–G:CHA scaffold 40:60 (w/w), 30:70 (w/w), and 20:80 (w/w), consecutively, are 4.2 Megapascals (MPa), 3.3 MPa, 2.2 MPa, and there are no significant differences with the p= 0.069 (p>0.05). The static biodegradation percentage after 21 days on each ratio variation of C–G:CHA scaffold 40:60 (w/w), 30:70 (w/w), and 20:80 (w/w) is 25.98%, 24.67%, and 20.64%. One-way ANOVA Welch test shows the result of the p-value as p<0.05. Conclusion: The compressive strength and static biodegradation of the C–G:CHA scaffold with ratio variations of 40:60 (w/w), 30:70 (w/w), and 20:80(w/w) fulfilled the requirements as a scaffold for bone tissue engineering.
... Table 3 compares our mechanical properties with the other similar researches achievements. Considering these results and the compression strength of the human cancellous bone, i.e., 2-12 MPa [36] , it can be proved that our prepared scaffolds can be successfully used for substitution of cancellous bone. However, there are many issues to fabricate scaffolds with high porosity and proper mechanical properties similar to those of a cancellous bone [36] . ...
... Considering these results and the compression strength of the human cancellous bone, i.e., 2-12 MPa [36] , it can be proved that our prepared scaffolds can be successfully used for substitution of cancellous bone. However, there are many issues to fabricate scaffolds with high porosity and proper mechanical properties similar to those of a cancellous bone [36] . Figure 9 illustrates the weight changes of all prepared scaffolds as a function of 3-week immersion time at PBS/lysozyme solutions. ...
Designing bone substitute scaffolds using soft materials with appropriate mechanical and biological features is still a challenging issue. In our current work, we have aimed to design biodegradable and bioactive nanocomposite systems by incorporation of ordered mesoporous SiO2–CaO–P2O5 (MBG) in chitosan-gelatin (CG) blends. MBG was derived by the combination of sol-gel/hydrothermal/evaporation-induced self-assembly (EISA) techniques. The FE-SEM results showed that MBG nanoparticles had almost spherical shape with good homogeneity and particle size of approximately smaller than 100 nm. TEM images confirmed that the order of mesostructures was enhanced depending on Si content where 85SiO2.10CaO.5P2O5 (M85S) had the most order of porosities. The highest surface area and pore volume belonged to M85S which were 389.01 m² g⁻¹ and 0.378 cm³ g⁻¹, respectively. Incorporation of M85S in CG makes macro-porous internal morphologies of scaffolds with pore sizes ranging from 20 to 120 μm. The introduction of MBG improved the compression strength of CG from 0.7 to 4.5 MPa. Moreover, the physicochemical properties including biodegradation rates and swelling ratios were decreased and the densities of scaffolds were increased. MTT and ALP assay results indicated no toxicity, proper cell attachments and proliferations on the pore surfaces and bone formation capability of scaffolds, respectively which were intensified by increasing the MBG content. These findings suggest that the developed scaffolds possess prerequisites and can be used as potential scaffolds for hard tissue regeneration.
... Scaffolds with specific compositions can drive cell differentiation towards preferred lineages for tissue engineering [7], [8]. Furthermore, the changes of stiffening behavior in scaffolds may affect the traction forces that cells apply to their matrix to alter the matrix [1], and correspond with the level of porosity and pore distribution [9]. An ideal engineered scaffold should have perfect integration with host tissues and be biocompatible [10], and its mechanical properties should be designed as close to native tissue as possible [11], [12]. ...
... Most mechanical characterization of scaffolds still relies on the DMA method for tissue engineering [3], [9], [14], [15]. Due to destruction of samples and the global nature of the elastic modulus measurement by using the DMA method, many important factors cannot be measured such as heterogeneity, elastic changes of cell-laden scaffolds associated with matrix mineralization and hydrogel degradations, which will be able to be addressed using AFEM. ...
https://www.embs.org/tbme/articles/acoustic-force-elastography-microscopy/
Acoustic Force Elastography Microscopy (featured article of TBME)
... It should also be noted that the value of the pore diameter is very important due to the mechanical properties of the obtained material. Too large a pore size and pore differentiation may translate into an increased risk of damage and cracking of the resulting layer [32]. ...
Osteoporosis is the most common metabolic disease of the skeletal system and is characterized by impaired bone strength. This translates into an increased risk of low-energy fractures, which means fractures caused by disproportionate force. This disease is quite insidious, its presence is usually detected only at an advanced stage, where treatment with pharmaceuticals does not produce sufficient results. It is obligatory to replace the weakened bone with an implant. For this reason, it is necessary to look at the possibilities of surface modification used in tissue engineering, which, in combination with the drugs for osteoporosis, i.e., bisphosphonates, may constitute a new and effective method for preventing the deterioration of the osteoporotic state. To achieve this purpose, titanium implants coated with magnesium or zinc zeolite were prepared. Both the sorption and release profiles differed depending on the type of ion in the zeolite structure. The successful release of risedronate from the materials at a low level was proven. It can be concluded that the proposed solution will allow the preparation of endoprostheses for patients with bone diseases such as osteoporosis.
... Alternatively, the in vitro and in vivo studies indicated that pore sizes of greater than 300 μm, microporosity of <20 μm, and interconnected open pores facilitate enhancing new bone formation and the generation of capillaries. 36,37 In addition, an interconnective porosity of 60− 75% is suggested for optimal cell growth. 11 A small pore favors hypoxic conditions and induces chondrogenesis, whereas a large pore benefits in vivo due to better nutrient supply, delayed pore occlusion, angiogenesis, and stimulation of new bone formation. ...
Polycaprolactone scaffolds were designed and 3D-printed with different pore shapes (cube and triangle) and sizes (500 and 700 μm) and modified with alkaline hydrolysis of different ratios (1, 3, and 5 M). In total, 16 designs were evaluated for their physical, mechanical, and biological properties. The present study mainly focused on the pore size, porosity, pore shapes, surface modification, biomineralization, mechanical properties, and biological characteristics that might influence bone ingrowth in 3D-printed biodegradable scaffolds. The results showed that the surface roughness in treated scaffolds increased compared to untreated polycaprolactone scaffolds (R a = 2.3-10.5 nm and R q = 17- 76 nm), but the structural integrity declined with an increase in the NaOH concentration especially in the scaffolds with small pores and a triangle shape. Overall, the treated polycaprolactone scaffolds particularly with the triangle shape and smaller pore size provided superior performance in mechanical strength similar to that of cancellous bone. Additionally, the in vitro study showed that cell viability increased in the polycaprolactone scaffolds with cubic pore shapes and small pore sizes, whereas mineralization was enhanced in the designs with larger pore sizes. Based on the results obtained, this study demonstrated that the 3D-printed modified polycaprolactone scaffolds exhibit a favorable mechanical property, biomineralization, and better biological properties; therefore, they can be applied in bone tissue engineering.
... Hence, CHL 3 was very brittle. Since the mechanical properties of the prepared scaffolds were lower than that of the cancellous bone (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12), it is expected that they can be used in the low weight bearing area or in small bone defects [43]. ...
This study aims at fabricating promising cytocompatible hybrid biocomposite scaffolds from chitosan (CS), hydroxyapatite (HAP) and lignin (L) for bonetissue engineering by using freeze-drying technique. Different ratios of HAP to L (50: 0, 37.5: 12.5, 25: 25 and 12.5: 37.5) were taken to determine the optimum ratio to obtain composite with superior properties. The mechanical and biological properties of the resulting composites were investigated. The mechanical results showed that the prepared composite with a ratio of 25 : 25 of HAP / L exhibited a remarkable enhancement in the mechanical properties compared to the others. Additionally, it was found from the in vitro results that the addition of L enhanced the water uptake value of the resulting scaffolds indicating increased hydrophilicity. As a result, a significant increase in the attachment and proliferation of MG-63 cell line (osteoblast like cells) was observed in composite scaffolds with L over the scaffold without L (CS/HAP). From these results, it could be suggested that the prepared composite scaffold with 25 : 25 of HAP/ L is very promising biomaterials in bone tissue-engineering as it exhibited a better mechanical and biological properties than the other prepared composites.
... Highest and lowest compression modulus of 39.25 MPa and 12.24 MPa were observed in case of SCF-7 and SCF-1 respectively, while in case of coated scaffolds, the SCF-4 and SCF-4C depicted compression modulus of 16.83 MPa and 19.61 MPa, respectively [45]. The compression strength test of biocomposite scaffolds suggested little or no particular change with coating probably due to highly porous structure. ...
The objective of present work is to fabricate porous three-dimensional biocomposite scaffolds with interconnected pore networks and mechanical strength for wound healing. Variable concentrations of chitosan and methylcellulose hydrogels were blended in the presence of calcium cations to prepare scaffolds by freeze-drying method. Curcumin-aerosol was deposited over the scaffold surface to improve antimicrobial efficacy. Scaffold stability and curcumin interaction were evaluated by Differential Scanning Calorimeter, Thermal Gravimetric Analyzer and Fourier Transform Infrared Spectrophotometer. Scanning Electron Microscopy indicate multi-layered porosity, mesh-like structure and pore-size ranging from 50 to 500 μm. Erythrocyte interaction with chitosan and methylcellulose using Surface Plasmon Resonance assay in the presence of curcumin depicted high binding affinity of chitosan alone than curcumin. The antibacterial activity of SCF-4C against Escherichia coli and Staphylococcus aureus and the instant haemostasis in erythrocyte-agglutination assay by SCF-7 indicate good material properties for wound treatment. Bleeding time and wound healing efficacy conducted on Sprague Dawley rats depict minimum clotting time of SCF-4 (∼32 ± 2 s) compared to SCF-4C (∼45 ± 2 s), while highest ∼85 ± 5 s was observed in curcumin alone. SCF-4C exhibit complete wound healing on day14 in diabetic animals. In-vivo studies confirmed that high concentration of chitosan in presence of curcumin enhances diabetic wound healing process.
... Scaffolds with specific compositions can drive cell differentiation towards preferred lineages for tissue engineering [7], [8]. Furthermore, the changes of stiffening behavior in scaffolds may affect the traction forces that cells apply to their matrix to alter the matrix [1], and correspond with the level of porosity and pore distribution [9]. An ideal engineered scaffold should have perfect integration with host tissues and be biocompatible [10], and its mechanical properties should be designed as close to native tissue as possible [11], [12]. ...
... Most mechanical characterization of scaffolds still relies on the DMA method for tissue engineering [3], [9], [14], [15]. Due to destruction of samples and the global nature of the elastic modulus measurement by using the DMA method, many important factors cannot be measured such as heterogeneity, elastic changes of cell-laden scaffolds associated with matrix mineralization and hydrogel degradations, which will be able to be addressed using AFEM. ...
Objective:
Hydrogel scaffolds have attracted attention to develop cellular therapy and tissue engineering platforms for regenerative medicine applications. Among factors, local mechanical properties of scaffolds drive the functionalities of cell niche. Dynamic mechanical analysis (DMA), the standard method to characterize mechanical properties of hydrogels, restricts development in tissue engineering because the measurement provides a single elasticity value for the sample, requires direct contact, and represents a destructive evaluation preventing longitudinal studies on the same sample. We propose a novel technique, acoustic force elastography microscopy (AFEM), to evaluate elastic properties of tissue engineering scaffolds.
Results:
AFEM can resolve localized and two-dimensional (2D) elastic properties of both transparent and opaque materials with advantages of being non-contact and non-destructive. Gelatin hydrogels, neat synthetic oligo[poly(ethylene glycol)fumarate] (OPF) scaffolds, OPF hydroxyapatite nanocomposite scaffolds and ex vivo biological tissue were examined with AFEM to evaluate the elastic modulus. These measurements of Young's modulus range from approximately 2 kPa to over 100 kPa were evaluated and are in good agreement with finite element simulations, surface wave measurements, and DMA tests.
Conclusion:
The AFEM can resolve localized and 2D elastic properties of hydrogels, scaffolds and thin biological tissues. These materials can either be transparent or non-transparent and their evaluation can be done in a non-contact and non-destructive manner, thereby facilitating longitudinal evaluation.
Significance:
AFEM is a promising technique to quantify elastic properties of scaffolds for tissue engineering and will be applied to provide new insights for exploring elastic changes of cell-laden scaffolds for tissue engineering and material science.
