Pub Date : 2025-02-17DOI: 10.1016/j.jmbbm.2025.106933
Rania Hadj Ali , Zohra Sghaier , Hélène Ageorges , Ezzedine Ben Salem , Mustapha Hidouri
Hydroxyfluorapatite (HFAp) materials possess a structural and compositional similarity to bone tissue and dentin. These bioceramics facilitate various physiological functions, including ion exchange within surface layers. Additionally, magnesium (Mg) serves as a primary substitute for calcium in the biological apatite found in the calcified tissues of mammals, while zinc (Zn) contributes to overall bone quality and exhibits antibacterial properties. Although multiple studies have examined the individual substitution of ions within the hydroxyapatite (HAp) structure, no research to date has investigated the simultaneous substitution of zinc, fluoride, and varying amounts of magnesium in calcium HAp. This study explores the incorporation of magnesium into the structure of zinc-calcium hydroxylfluorapatite. A series of ion-substituted apatites, represented as Ca9.9-xZn0.1Mgx (PO4)6(OH)F with 0 ≤ x ≤ 1, were synthesized. Characterization of the produced samples confirmed that they were monophase apatite, crystallizing in the hexagonal P63/m space group, with only a slight impact on crystallinity due to magnesium doping. Pressure-less sintering of the samples demonstrated that maximum densification, approximately 94%, was achieved at 1200 °C with a sintering dwell of 1 h for the sample with x = 0.1. Furthermore, the Young's and Vickers hardness of this sample reached peak values of 105 and 5.02 GPa, respectively. When immersed in simulated body fluid, the formation of an amorphous CaP which can subsequently be crystallized into crystalline phase on the surface of dense specimens was observed, indicating the ability to bond with bone in a living organism and their potential use as substitutes for failed bone and dentin filling and coating.
{"title":"Magnesium-substituted zinc-calcium hydroxyfluorapatite bioceramics for bone tissue engineering","authors":"Rania Hadj Ali , Zohra Sghaier , Hélène Ageorges , Ezzedine Ben Salem , Mustapha Hidouri","doi":"10.1016/j.jmbbm.2025.106933","DOIUrl":"10.1016/j.jmbbm.2025.106933","url":null,"abstract":"<div><div>Hydroxyfluorapatite (HFAp) materials possess a structural and compositional similarity to bone tissue and dentin. These bioceramics facilitate various physiological functions, including ion exchange within surface layers. Additionally, magnesium (Mg) serves as a primary substitute for calcium in the biological apatite found in the calcified tissues of mammals, while zinc (Zn) contributes to overall bone quality and exhibits antibacterial properties. Although multiple studies have examined the individual substitution of ions within the hydroxyapatite (HAp) structure, no research to date has investigated the simultaneous substitution of zinc, fluoride, and varying amounts of magnesium in calcium HAp. This study explores the incorporation of magnesium into the structure of zinc-calcium hydroxylfluorapatite. A series of ion-substituted apatites, represented as Ca<sub>9.9-x</sub>Zn<sub>0.1</sub>Mgx (PO<sub>4</sub>)<sub>6</sub>(OH)F with 0 ≤ x ≤ 1, were synthesized. Characterization of the produced samples confirmed that they were monophase apatite, crystallizing in the hexagonal P63/m space group, with only a slight impact on crystallinity due to magnesium doping. Pressure-less sintering of the samples demonstrated that maximum densification, approximately 94%, was achieved at 1200 °C with a sintering dwell of 1 h for the sample with x = 0.1. Furthermore, the Young's and Vickers hardness of this sample reached peak values of 105 and 5.02 GPa, respectively. When immersed in simulated body fluid, the formation of an amorphous CaP which can subsequently be crystallized into crystalline phase on the surface of dense specimens was observed, indicating the ability to bond with bone in a living organism and their potential use as substitutes for failed bone and dentin filling and coating.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"166 ","pages":"Article 106933"},"PeriodicalIF":3.3,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143463674","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-17DOI: 10.1016/j.jmbbm.2025.106959
Zhongliang Yu , Lin Yu , Wenqing Zhu , Junjie Liu , Xiaoding Wei
Plastic metals and low-dimensional materials are extensively utilized as reinforcements in fabricating bio-inspired staggered composites. Here, we introduce a comprehensive analytical model to investigate the influence of reinforcement plasticity on the mechanical properties of staggered composites while preserving the non-linear plastic characteristics of the matrix. Competitive plastic deformation in both the reinforcement and the matrix leads to two distinct deformation modes: reinforcement-first yield or matrix-first yield. Each mode exhibits different stages of deformation and failure in plastic staggered composites. Our analytical formulae, validated via finite element analysis, establish connections between effective stress and strain responses, material compositions, and structural geometry, thereby revealing non-linear shear stress transfer and plastic evolution mechanisms. Furthermore, we discover that tailoring the plasticity of the reinforcement while maintaining the dominant plastic deformation of the matrix, can overcome the trade-off between composite strength and ductility. Our model provides valuable insights into designing high-performance metal-reinforced staggered composites and can be further extended to explore the mechanical properties of plastic low-dimensional material-reinforced nanocomposites with noncovalent interfaces.
{"title":"An analytical model for customizing reinforcement plasticity to address the strength-ductility trade-off in staggered composites","authors":"Zhongliang Yu , Lin Yu , Wenqing Zhu , Junjie Liu , Xiaoding Wei","doi":"10.1016/j.jmbbm.2025.106959","DOIUrl":"10.1016/j.jmbbm.2025.106959","url":null,"abstract":"<div><div>Plastic metals and low-dimensional materials are extensively utilized as reinforcements in fabricating bio-inspired staggered composites. Here, we introduce a comprehensive analytical model to investigate the influence of reinforcement plasticity on the mechanical properties of staggered composites while preserving the non-linear plastic characteristics of the matrix. Competitive plastic deformation in both the reinforcement and the matrix leads to two distinct deformation modes: reinforcement-first yield or matrix-first yield. Each mode exhibits different stages of deformation and failure in plastic staggered composites. Our analytical formulae, validated via finite element analysis, establish connections between effective stress and strain responses, material compositions, and structural geometry, thereby revealing non-linear shear stress transfer and plastic evolution mechanisms. Furthermore, we discover that tailoring the plasticity of the reinforcement while maintaining the dominant plastic deformation of the matrix, can overcome the trade-off between composite strength and ductility. Our model provides valuable insights into designing high-performance metal-reinforced staggered composites and can be further extended to explore the mechanical properties of plastic low-dimensional material-reinforced nanocomposites with noncovalent interfaces.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"166 ","pages":"Article 106959"},"PeriodicalIF":3.3,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143453633","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-16DOI: 10.1016/j.jmbbm.2025.106955
Hamed Hatami-Marbini, Md Esharuzzaman Emu
The cornea is a transparent tissue whose mechanical properties are important for its optical and physiological functions. The mechanical properties of cornea depend on the composition and microstructure of its extracellular matrix, which is composed of collagen fibrils with preferential orientations. The present research was done in order to characterize corneal mechanical response using the biaxial mechanical testing method and to compare biaxial measurements with those found from uniaxial tensile tests. For this purpose, thirty square-shaped specimens excised from the center of porcine cornea were mounted into an ElectroForce TestBench device such that their superior/inferior (SI) and nasal/temporal (NT) meridians were aligned with motor axes. Furthermore, ten corneal strips dissected from the NT direction (n = 5) and SI direction (n = 5) were mounted into an RSA-G2 Solid Analyzer testing machine. The biaxial experiments were performed at stretch ratios of 1:1, 1:0.5, 0.5:1, 1:0.01, and 0.01:1 and displacement rates of 2 mm/min (n = 20) and 10 mm/min (n = 10). The uniaxial experiments were done using the displacement rate of 2 mm/min. The planar square-shaped samples tested under equibiaxial loading showed similar mechanical response in NT and SI directions. Furthermore, uniaxial experiments revealed no significant difference in tensile response of corneal strips excised from NT and SI directions. However, equibiaxial testing tensile stresses were significantly larger than those found from uniaxial tensile measurements. The mechanical behavior of cornea in biaxial tests was dependent on the applied stretch ratio. The differences and similarities between uniaxial and biaxial experimental measurements were discussed and it was concluded that the planar biaxial testing method characterized the mechanical response of cornea by mimicking its in vivo loading state more closely than uniaxial experiments.
{"title":"Biomechanical properties of porcine cornea; planar biaxial tests versus uniaxial tensile tests","authors":"Hamed Hatami-Marbini, Md Esharuzzaman Emu","doi":"10.1016/j.jmbbm.2025.106955","DOIUrl":"10.1016/j.jmbbm.2025.106955","url":null,"abstract":"<div><div>The cornea is a transparent tissue whose mechanical properties are important for its optical and physiological functions. The mechanical properties of cornea depend on the composition and microstructure of its extracellular matrix, which is composed of collagen fibrils with preferential orientations. The present research was done in order to characterize corneal mechanical response using the biaxial mechanical testing method and to compare biaxial measurements with those found from uniaxial tensile tests. For this purpose, thirty square-shaped specimens excised from the center of porcine cornea were mounted into an ElectroForce TestBench device such that their superior/inferior (SI) and nasal/temporal (NT) meridians were aligned with motor axes. Furthermore, ten corneal strips dissected from the NT direction (n = 5) and SI direction (n = 5) were mounted into an RSA-G2 Solid Analyzer testing machine. The biaxial experiments were performed at stretch ratios of 1:1, 1:0.5, 0.5:1, 1:0.01, and 0.01:1 and displacement rates of 2 mm/min (n = 20) and 10 mm/min (n = 10). The uniaxial experiments were done using the displacement rate of 2 mm/min. The planar square-shaped samples tested under equibiaxial loading showed similar mechanical response in NT and SI directions. Furthermore, uniaxial experiments revealed no significant difference in tensile response of corneal strips excised from NT and SI directions. However, equibiaxial testing tensile stresses were significantly larger than those found from uniaxial tensile measurements. The mechanical behavior of cornea in biaxial tests was dependent on the applied stretch ratio. The differences and similarities between uniaxial and biaxial experimental measurements were discussed and it was concluded that the planar biaxial testing method characterized the mechanical response of cornea by mimicking its in vivo loading state more closely than uniaxial experiments.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"166 ","pages":"Article 106955"},"PeriodicalIF":3.3,"publicationDate":"2025-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143464458","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-15DOI: 10.1016/j.jmbbm.2025.106952
Joanna Zemła , Claude Verdier , Marcin Luty , Joanna Pabijan , Małgorzata Lekka
Cytoskeleton targeting agents are a group of chemotherapeutics used in the therapy of many types of cancer, such as breast, prostate, lung, bladder cancer, and others. At the same time, the assessment of the rheological properties of cancer cells is a relevant marker of their metastatic potential and therapeutic efficacy. For these reasons, understanding the interaction between the actin microfilament (MFs) network, microtubules (MTs), and so-called intermediate filaments (IFs) is crucial for the use of the rheological properties of cells as biomechanical markers. The current work compares the rheological properties of bladder cancer cells T24 and 5637, which differ in cytoskeletal composition, treated with a low dose of docetaxel (DTX) - a microtubule targeting agent (MTA). AFM revealed that 5637 cells stiffen over time when exposed to DTX, whereas changes in rheological properties of T24 cells are less pronounced, and both softening and stiffening of cells are observed. From immunostaining and Western blot analysis, we found that in addition to changes in the content and organization of MTs, reorganization of MFs and vimentin IFs also occurs. We show that both cell and nucleus morphology changes after DTX treatment. DTX treatment decreases and increases the migratory potential of 5637 and T24 cells, respectively. The current work shows that vimentin IFs modulate the nanomechanics of bladder cancer cells.
{"title":"Mechanical modulation of docetaxel-treated bladder cancer cells by various changes in cytoskeletal structures","authors":"Joanna Zemła , Claude Verdier , Marcin Luty , Joanna Pabijan , Małgorzata Lekka","doi":"10.1016/j.jmbbm.2025.106952","DOIUrl":"10.1016/j.jmbbm.2025.106952","url":null,"abstract":"<div><div>Cytoskeleton targeting agents are a group of chemotherapeutics used in the therapy of many types of cancer, such as breast, prostate, lung, bladder cancer, and others. At the same time, the assessment of the rheological properties of cancer cells is a relevant marker of their metastatic potential and therapeutic efficacy. For these reasons, understanding the interaction between the actin microfilament (MFs) network, microtubules (MTs), and so-called intermediate filaments (IFs) is crucial for the use of the rheological properties of cells as biomechanical markers. The current work compares the rheological properties of bladder cancer cells T24 and 5637, which differ in cytoskeletal composition, treated with a low dose of docetaxel (DTX) - a microtubule targeting agent (MTA). AFM revealed that 5637 cells stiffen over time when exposed to DTX, whereas changes in rheological properties of T24 cells are less pronounced, and both softening and stiffening of cells are observed. From immunostaining and Western blot analysis, we found that in addition to changes in the content and organization of MTs, reorganization of MFs and vimentin IFs also occurs. We show that both cell and nucleus morphology changes after DTX treatment. DTX treatment decreases and increases the migratory potential of 5637 and T24 cells, respectively. The current work shows that vimentin IFs modulate the nanomechanics of bladder cancer cells.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"165 ","pages":"Article 106952"},"PeriodicalIF":3.3,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143437302","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-13DOI: 10.1016/j.jmbbm.2025.106935
Rachel Laytin, Guy K. German
Finger wrinkling during and after water immersion, often called pruning, is an evolutionary mechanism that increases grip strength in water. Previous studies have determined that water-induced finger wrinkles result from vasoconstriction, or the tightening of blood vessels below the skin's surface. However, no previous studies have characterized the morphology of topographical finger wrinkles. We anticipate that vasoconstriction also governs the morphology of finger wrinkles formed. Since these constricting blood vessels are stationary, we expect the pattern created by topographical wrinkles formed to remain constant over time. To evaluate pattern repeatability, images of human fingertips at two separate time points are overlaid and compared visually to establish corresponding wrinkle pairs. Wrinkle pairs are vectorized with orientation correlations evaluated quantitatively using normalized dot products, then compared against randomly oriented control vectors. The results demonstrate a significant relationship between wrinkle orientation across both time points and thus reveal the consistency of wrinkle morphology over time.
{"title":"On the repeatability of wrinkling topography patterns in the fingers of water immersed human skin","authors":"Rachel Laytin, Guy K. German","doi":"10.1016/j.jmbbm.2025.106935","DOIUrl":"10.1016/j.jmbbm.2025.106935","url":null,"abstract":"<div><div>Finger wrinkling during and after water immersion, often called pruning, is an evolutionary mechanism that increases grip strength in water. Previous studies have determined that water-induced finger wrinkles result from vasoconstriction, or the tightening of blood vessels below the skin's surface. However, no previous studies have characterized the morphology of topographical finger wrinkles. We anticipate that vasoconstriction also governs the morphology of finger wrinkles formed. Since these constricting blood vessels are stationary, we expect the pattern created by topographical wrinkles formed to remain constant over time. To evaluate pattern repeatability, images of human fingertips at two separate time points are overlaid and compared visually to establish corresponding wrinkle pairs. Wrinkle pairs are vectorized with orientation correlations evaluated quantitatively using normalized dot products, then compared against randomly oriented control vectors. The results demonstrate a significant relationship between wrinkle orientation across both time points and thus reveal the consistency of wrinkle morphology over time.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"165 ","pages":"Article 106935"},"PeriodicalIF":3.3,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143427941","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-13DOI: 10.1016/j.jmbbm.2025.106951
Dandan Zhu , Xiaoqiang Li , Shaoyu Chai , Tien-Shee Chee , Chaerin Kim , Liang Li , Dexue Liu
As a promising material for medical implants, the Ti40Zr40Nb5Ta12Sn3 medium entropy alloy (MEA) shows potential for biomedical applications. This study investigates its wear and corrosion behavior in simulated biological environments, including artificial saliva (AS), simulated blood (SB), and simulated body fluid (SBF). Electrochemical tests revealed excellent corrosion resistance in AS solution, with a higher corrosion potential (−0.31420 V) and a lower corrosion current density (2.613 × 10⁻⁷ A·cm⁻2). Wear tests showed that friction coefficients ranked as μAS > μSBF > μSB, while wear rates followed δSBF > δSB > δAS, highlighting the impact of bio-lubricants composition on tribological behavior. In particular, the alloy exhibited a higher ion release rate in the SBF solution, with ion concentrations approximately 2.5 times greater than those in the AS solution. In contrast, the alloy in the AS solution maintained a more stable passivation film, thus reducing ion release and enhancing both wear and corrosion resistance of the alloy. The biocompatibility test further confirmed that it has good cell adhesion and proliferation ability. This study provides valuable insights into the synergistic effects of wear and corrosion on the alloy in simulated physiological environments.
{"title":"Evaluation of wear, corrosion, and biocompatibility of a novel biomedical TiZr-based medium entropy alloy","authors":"Dandan Zhu , Xiaoqiang Li , Shaoyu Chai , Tien-Shee Chee , Chaerin Kim , Liang Li , Dexue Liu","doi":"10.1016/j.jmbbm.2025.106951","DOIUrl":"10.1016/j.jmbbm.2025.106951","url":null,"abstract":"<div><div>As a promising material for medical implants, the Ti<sub>40</sub>Zr<sub>40</sub>Nb<sub>5</sub>Ta<sub>12</sub>Sn<sub>3</sub> medium entropy alloy (MEA) shows potential for biomedical applications. This study investigates its wear and corrosion behavior in simulated biological environments, including artificial saliva (AS), simulated blood (SB), and simulated body fluid (SBF). Electrochemical tests revealed excellent corrosion resistance in AS solution, with a higher corrosion potential (−0.31420 V) and a lower corrosion current density (2.613 × 10⁻⁷ A·cm⁻<sup>2</sup>). Wear tests showed that friction coefficients ranked as <em>μ</em><sub>AS</sub> > <em>μ</em><sub>SBF</sub> > <em>μ</em><sub>SB</sub>, while wear rates followed <em>δ</em><sub>SBF</sub> > <em>δ</em><sub>SB</sub> > <em>δ</em><sub>AS</sub>, highlighting the impact of bio-lubricants composition on tribological behavior. In particular, the alloy exhibited a higher ion release rate in the SBF solution, with ion concentrations approximately 2.5 times greater than those in the AS solution. In contrast, the alloy in the AS solution maintained a more stable passivation film, thus reducing ion release and enhancing both wear and corrosion resistance of the alloy. The biocompatibility test further confirmed that it has good cell adhesion and proliferation ability. This study provides valuable insights into the synergistic effects of wear and corrosion on the alloy in simulated physiological environments.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"165 ","pages":"Article 106951"},"PeriodicalIF":3.3,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143427940","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-13DOI: 10.1016/j.jmbbm.2025.106922
Kim Busenhart , Julie Brun , Håvar Junker , Alexander E. Ehret , Alba Marcellan , Edoardo Mazza
Understanding the mechanical properties of collagen hydrogels is essential for successful applications in tissue engineering and 3D cell culture. This study compares the mechanical behavior of two collagen hydrogel sheets with similar collagen content but different microstructures. One of the differences is that one gel is isotropic while the other has collagen fibers oriented towards the sheet’s plane. Experiments were performed at macro- (uniaxial tension in the sheet plane) and micro-length scale (AFM-based indentation perpendicular to the plane), and a discrete network model was developed to rationalize the observed differences. The experiments showed an order of magnitude difference in the uniaxial stiffness of the two gels. The softer gel exhibited near-incompressible behavior, while the stiffer gel showed a highly contractile response, with Poisson’s ratios around 8. Conversely, the apparent modulus from nano-indentation showed an opposite trend, with higher local stiffness for the gel that was softer in uniaxial tests. The computational model represents the material using a network of bi-linear connectors for the fibrous component and a compressible neo-Hookean material for the surrounding water-rich matrix, assumed to form due to interactions between collagen and water. Under the constraint of equal collagen content, model parameters were tuned to reproduce the observed response of both materials, considering the observed differences in fiber diameter. Importantly, the computations indicate that the difference in collagen orientation cannot explain the observed differences between the mechanical responses of the gels. Successful scaling between the two gels depends on the assumption that, due to their crimped initial state individual fibers primarily experience bending rather than tension when the material is stretched. Moreover, high tensile stretch of the fibers is shown to elicit large lateral contraction. Overall, the results demonstrate the wide range of mechanical properties displayed by hydrogels with similar collagen content, which can be rationalized using discrete models representative of their microstructure.
{"title":"Collagen hydrogels with similar polymer content but different microstructure — A comparative analysis of mechanical response","authors":"Kim Busenhart , Julie Brun , Håvar Junker , Alexander E. Ehret , Alba Marcellan , Edoardo Mazza","doi":"10.1016/j.jmbbm.2025.106922","DOIUrl":"10.1016/j.jmbbm.2025.106922","url":null,"abstract":"<div><div>Understanding the mechanical properties of collagen hydrogels is essential for successful applications in tissue engineering and 3D cell culture. This study compares the mechanical behavior of two collagen hydrogel sheets with similar collagen content but different microstructures. One of the differences is that one gel is isotropic while the other has collagen fibers oriented towards the sheet’s plane. Experiments were performed at macro- (uniaxial tension in the sheet plane) and micro-length scale (AFM-based indentation perpendicular to the plane), and a discrete network model was developed to rationalize the observed differences. The experiments showed an order of magnitude difference in the uniaxial stiffness of the two gels. The softer gel exhibited near-incompressible behavior, while the stiffer gel showed a highly contractile response, with Poisson’s ratios around 8. Conversely, the apparent modulus from nano-indentation showed an opposite trend, with higher local stiffness for the gel that was softer in uniaxial tests. The computational model represents the material using a network of bi-linear connectors for the fibrous component and a compressible neo-Hookean material for the surrounding water-rich matrix, assumed to form due to interactions between collagen and water. Under the constraint of equal collagen content, model parameters were tuned to reproduce the observed response of both materials, considering the observed differences in fiber diameter. Importantly, the computations indicate that the difference in collagen orientation cannot explain the observed differences between the mechanical responses of the gels. Successful scaling between the two gels depends on the assumption that, due to their crimped initial state individual fibers primarily experience bending rather than tension when the material is stretched. Moreover, high tensile stretch of the fibers is shown to elicit large lateral contraction. Overall, the results demonstrate the wide range of mechanical properties displayed by hydrogels with similar collagen content, which can be rationalized using discrete models representative of their microstructure.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"166 ","pages":"Article 106922"},"PeriodicalIF":3.3,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143463673","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-12DOI: 10.1016/j.jmbbm.2025.106950
Olivia N. Reul, Rachel K. Surowiec, Nusaiba N. Chowdhury, Dyann M. Segvich, Joseph M. Wallace
The use of compressive axial tibial loading for evaluation of bone adaptation and mechanotransduction has become a common technique in recent years. Despite its popularity, it only produces a single experimental limb per animal which can escalate sample sizes depending on study endpoints. We hypothesized the combination of compressive axial tibial and ulnar loading in a single animal would induce bone formation in loaded limbs, providing two experimental limbs per animal thereby reducing the animals required per study by half. Male and female C57BL/6J mice were purchased at 9 and 19 weeks (wks). Based on sex and age they were divided into 4 groups of N = 17. From each group, N = 5 were sacrificed at 10 and 20 wks for strain gauge calibration. At 11 wks and 21 wks, the left ulnae and right tibiae of the remaining animals (N = 12/group) were loaded 3 days/week for 4 weeks. Tibiae of all groups experienced significant increases in architectural properties due to loading in both trabecular and cortical compartments while there were no significant improvements in the ulna. Female tibiae showed improvements in mechanical properties, but these were not observed in the male tibiae where detrimental impacts were observed. In the ulna, females showed limited mechanical changes due to loading. Contrastingly, loading in males at 11 wks led to decreased mechanical properties while at 21 wks no impacts were observed. Overall, reported beneficial impacts of loading in tibiae were observed in architectural properties but were not maintained in the males’ mechanical properties. Impacts of ulnar loading on architectural and whole bone mechanical properties that have been reported elsewhere were not observed in any groups. These data suggest when architectural and mechanical properties are end points, combined loading is not optimal for reducing the number of animals required per study.
{"title":"Skeletal impacts of dual in vivo compressive axial tibial and ulnar loading in mice","authors":"Olivia N. Reul, Rachel K. Surowiec, Nusaiba N. Chowdhury, Dyann M. Segvich, Joseph M. Wallace","doi":"10.1016/j.jmbbm.2025.106950","DOIUrl":"10.1016/j.jmbbm.2025.106950","url":null,"abstract":"<div><div>The use of compressive axial tibial loading for evaluation of bone adaptation and mechanotransduction has become a common technique in recent years. Despite its popularity, it only produces a single experimental limb per animal which can escalate sample sizes depending on study endpoints. We hypothesized the combination of compressive axial tibial and ulnar loading in a single animal would induce bone formation in loaded limbs, providing two experimental limbs per animal thereby reducing the animals required per study by half. Male and female C57BL/6J mice were purchased at 9 and 19 weeks (wks). Based on sex and age they were divided into 4 groups of N = 17. From each group, N = 5 were sacrificed at 10 and 20 wks for strain gauge calibration. At 11 wks and 21 wks, the left ulnae and right tibiae of the remaining animals (N = 12/group) were loaded 3 days/week for 4 weeks. Tibiae of all groups experienced significant increases in architectural properties due to loading in both trabecular and cortical compartments while there were no significant improvements in the ulna. Female tibiae showed improvements in mechanical properties, but these were not observed in the male tibiae where detrimental impacts were observed. In the ulna, females showed limited mechanical changes due to loading. Contrastingly, loading in males at 11 wks led to decreased mechanical properties while at 21 wks no impacts were observed. Overall, reported beneficial impacts of loading in tibiae were observed in architectural properties but were not maintained in the males’ mechanical properties. Impacts of ulnar loading on architectural and whole bone mechanical properties that have been reported elsewhere were not observed in any groups. These data suggest when architectural and mechanical properties are end points, combined loading is not optimal for reducing the number of animals required per study.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"165 ","pages":"Article 106950"},"PeriodicalIF":3.3,"publicationDate":"2025-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143420170","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-11DOI: 10.1016/j.jmbbm.2025.106939
Neilesh R. Frings , Elise F. Morgan
<div><div>The endplate region of the vertebra, which includes the bony endplate (BEP) and underlying subchondral trabecular bone (STB), is critically involved in vertebral fracture (VF). While evidence abounds that failure initiates in the endplate region, the relative risk of failure of the BEP vs. STB has not been established. In this study, micro-finite element models were constructed of L1 vertebrae (n = 21) that were mechanically tested in a prior study and given experimentally matched boundary conditions corresponding to the vertebra's yield point. Volumes of interest (VOIs) were defined corresponding to the BEP and STB; the remainder was defined as the mid-vertebral body (MVB). The proportion of elements within each VOI that yielded was defined as the VOI yield fraction, and this value divided by the yield fraction of the entire model was defined as the normalized yield fraction. While yield fraction did not differ across VOIs (p = 0.179), normalized yield fraction was greater in the BEP than STB and MVB (p < 0.001), indicating a higher risk of yield in the BEP compared to the other two VOIs. None of the yield fractions was correlated with BEP or STB microstructure, and tension (rather than compression) was the dominant mode of tissue level yield. These findings indicate that the BEP, more so than the STB, is likely the site of VF initiation and that current methods of screening for VF risk, because they omit specific analysis of the BEP, are missing the region that matters the most.</div><div>The endplate region of the vertebra, which includes the bony endplate (BEP) and underlying subchondral bone (SB), is critically involved in vertebral fracture (VF). While evidence abounds that failure initiates in the endplate region, the relative risk of failure of the BEP vs. SB has not been established. In this study, micro-finite element models were constructed of L1 vertebrae (n = 21) that had been mechanically tested in a prior study, and they were given experimentally matched boundary conditions corresponding to the vertebra's yield point. Volumes of interest (VOIs) were defined corresponding to the BEP and SB; the remainder was defined as the mid-vertebral body (MVB). The proportion of yielded elements within each VOI was defined as the VOI yield fraction, and this value divided by the yield fraction of the entire model was defined as the normalized yield fraction. While yield fraction did not differ across VOIs (p = 0.179), normalized yield fraction was greater in the BEP than SB and MVB (p < 0.001), indicating a higher risk of yield in the BEP compared to the other two VOIs. None of the yield fractions was correlated with BEP or SB microstructure, and tension (rather than compression) was the dominant mode of tissue level yield. These findings indicate that the BEP, more so than the SB, is likely the site of VF initiation and that current methods of screening for VF risk, because they omit specific analysis of the BEP, are missing the
{"title":"Risk of bony endplate failure during vertebral fracture","authors":"Neilesh R. Frings , Elise F. Morgan","doi":"10.1016/j.jmbbm.2025.106939","DOIUrl":"10.1016/j.jmbbm.2025.106939","url":null,"abstract":"<div><div>The endplate region of the vertebra, which includes the bony endplate (BEP) and underlying subchondral trabecular bone (STB), is critically involved in vertebral fracture (VF). While evidence abounds that failure initiates in the endplate region, the relative risk of failure of the BEP vs. STB has not been established. In this study, micro-finite element models were constructed of L1 vertebrae (n = 21) that were mechanically tested in a prior study and given experimentally matched boundary conditions corresponding to the vertebra's yield point. Volumes of interest (VOIs) were defined corresponding to the BEP and STB; the remainder was defined as the mid-vertebral body (MVB). The proportion of elements within each VOI that yielded was defined as the VOI yield fraction, and this value divided by the yield fraction of the entire model was defined as the normalized yield fraction. While yield fraction did not differ across VOIs (p = 0.179), normalized yield fraction was greater in the BEP than STB and MVB (p < 0.001), indicating a higher risk of yield in the BEP compared to the other two VOIs. None of the yield fractions was correlated with BEP or STB microstructure, and tension (rather than compression) was the dominant mode of tissue level yield. These findings indicate that the BEP, more so than the STB, is likely the site of VF initiation and that current methods of screening for VF risk, because they omit specific analysis of the BEP, are missing the region that matters the most.</div><div>The endplate region of the vertebra, which includes the bony endplate (BEP) and underlying subchondral bone (SB), is critically involved in vertebral fracture (VF). While evidence abounds that failure initiates in the endplate region, the relative risk of failure of the BEP vs. SB has not been established. In this study, micro-finite element models were constructed of L1 vertebrae (n = 21) that had been mechanically tested in a prior study, and they were given experimentally matched boundary conditions corresponding to the vertebra's yield point. Volumes of interest (VOIs) were defined corresponding to the BEP and SB; the remainder was defined as the mid-vertebral body (MVB). The proportion of yielded elements within each VOI was defined as the VOI yield fraction, and this value divided by the yield fraction of the entire model was defined as the normalized yield fraction. While yield fraction did not differ across VOIs (p = 0.179), normalized yield fraction was greater in the BEP than SB and MVB (p < 0.001), indicating a higher risk of yield in the BEP compared to the other two VOIs. None of the yield fractions was correlated with BEP or SB microstructure, and tension (rather than compression) was the dominant mode of tissue level yield. These findings indicate that the BEP, more so than the SB, is likely the site of VF initiation and that current methods of screening for VF risk, because they omit specific analysis of the BEP, are missing the","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"165 ","pages":"Article 106939"},"PeriodicalIF":3.3,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143420168","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-11DOI: 10.1016/j.jmbbm.2025.106941
Maximilian Pestel , Jürgen Alphonsus , Stefan Toegel , Andreas Strassl , Johannes Herold , Reinhard Windhager , Emir Benca
Objective
Implant removal is a common method to quantify the level of osseointegration in small animal studies. Due to small implant sizes, precise alignment in removal experiments is crucial to obtain accurate and reproducible results. This study proposes a novel approach using photon counting detector computed tomography (PCD-CT) data and additive manufacturing to improve implant alignment.
Methods
A simplified finite element model was designed to investigate the effect of implant misalignment in removal tests. Additionally, the geometry of 43 rat tibiae was assessed utilizing PCD-CT scans, and subsequently specimen-specific positioning fixtures were designed and manufactured using computer-aided design and tabletop 3D printers. The accuracy and precision of the specimen alignment within the fixtures were assessed both visually (current state of the art) and through projectional radiography in both cranial-caudal (CC) and anterior-posterior (AP) projections to quantify true misalignment.
Results
Finite element analysis demonstrated that stresses and displacements are sensitive to misalignment, potentially leading to substantial inaccuracies in the implant removal measurements. Statistical analysis of visual assessments revealed poor to moderate inter- and intra-operator variability (0.336 ≤ ICC ≤ 0.625) and low correlation with true misalignment (0.024 ≤ R2 ≤ 0.204). Specimen alignment within the fixtures (CC: 0.23 ± 0.46°, AP: 1.00 ± 0.82°) showed improvement in accuracy and precision compared to visual assessments (CC: 0.88 ± 0.92°, AP: 1.11 ± 1.15°).
Conclusion
The proposed specimen fixation and alignment, which relies on clinical imaging data and inexpensive 3D printers, offers a cost- and time-effective alternative to visual assessments, which could considerably improve the accuracy and precision in osseointegration assessment.
{"title":"Improving accuracy in assessing osseointegration in small animal bone using specimen-specific additively-manufactured fixtures based on clinical CT imaging","authors":"Maximilian Pestel , Jürgen Alphonsus , Stefan Toegel , Andreas Strassl , Johannes Herold , Reinhard Windhager , Emir Benca","doi":"10.1016/j.jmbbm.2025.106941","DOIUrl":"10.1016/j.jmbbm.2025.106941","url":null,"abstract":"<div><h3>Objective</h3><div>Implant removal is a common method to quantify the level of osseointegration in small animal studies. Due to small implant sizes, precise alignment in removal experiments is crucial to obtain accurate and reproducible results. This study proposes a novel approach using photon counting detector computed tomography (PCD-CT) data and additive manufacturing to improve implant alignment.</div></div><div><h3>Methods</h3><div>A simplified finite element model was designed to investigate the effect of implant misalignment in removal tests. Additionally, the geometry of 43 rat tibiae was assessed utilizing PCD-CT scans, and subsequently specimen-specific positioning fixtures were designed and manufactured using computer-aided design and tabletop 3D printers. The accuracy and precision of the specimen alignment within the fixtures were assessed both visually (current state of the art) and through projectional radiography in both cranial-caudal (CC) and anterior-posterior (AP) projections to quantify true misalignment.</div></div><div><h3>Results</h3><div>Finite element analysis demonstrated that stresses and displacements are sensitive to misalignment, potentially leading to substantial inaccuracies in the implant removal measurements. Statistical analysis of visual assessments revealed poor to moderate inter- and intra-operator variability (0.336 ≤ ICC ≤ 0.625) and low correlation with true misalignment (0.024 ≤ R<sup>2</sup> ≤ 0.204). Specimen alignment within the fixtures (CC: 0.23 ± 0.46°, AP: 1.00 ± 0.82°) showed improvement in accuracy and precision compared to visual assessments (CC: 0.88 ± 0.92°, AP: 1.11 ± 1.15°).</div></div><div><h3>Conclusion</h3><div>The proposed specimen fixation and alignment, which relies on clinical imaging data and inexpensive 3D printers, offers a cost- and time-effective alternative to visual assessments, which could considerably improve the accuracy and precision in osseointegration assessment.</div></div>","PeriodicalId":380,"journal":{"name":"Journal of the Mechanical Behavior of Biomedical Materials","volume":"165 ","pages":"Article 106941"},"PeriodicalIF":3.3,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143453550","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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