1
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Xiao P, Roy A, Wang X. In-silico simulation of nanoindentation on bone using a 2D cohesive finite element model. J Mech Behav Biomed Mater 2024; 151:106403. [PMID: 38237206 DOI: 10.1016/j.jmbbm.2024.106403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 01/10/2024] [Accepted: 01/11/2024] [Indexed: 02/03/2024]
Abstract
This study proposed and validated a 2D finite element (FE) model for conducting in-silico simulations of in-situ nanoindentation tests on mineralized collagen fibrils (MCF) and the extrafibrillar matrix (EFM) within human cortical bone. Initially, a multiscale cohesive FE model was developed by adapting a previous model of bone lamellae, encompassing both MCF and EFM. Subsequently, nanoindentation tests were simulated in-silico using this model, and the resulting predictions were compared to AFM nanoindentation test data to verify the model's accuracy. The FE model accurately predicted nanoindentation results under wet conditions, closely aligning with outcomes obtained from AFM nanoindentation tests. Specifically, it successfully mirrored the traction/separation curve, nanoindentation modulus, plastic energy dissipation, and plastic energy ratio obtained from AFM nanoindentation tests. Additionally, this in-silico model demonstrated its ability to capture alterations in nanoindentation properties caused by the removal of bound water, by considering corresponding changes in mechanical properties of the collagen phase and the interfaces among bone constituents. Notably, significant changes in the elastic modulus and plastic energy dissipation were observed in both MCF and EFM compartments of bone, consistent with observations in AFM nanoindentation tests. These findings indicate that the proposed in-silico model effectively captures the influence of ultrastructural changes on bone's mechanical properties at sub-lamellar levels. Presently, no experimental methods exist to conduct parametric studies elucidating the ultrastructural origins of bone tissue fragility. The introduction of this in-silico model presents an invaluable tool to bridge this knowledge gap in the future.
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Affiliation(s)
- Pengwei Xiao
- Department of Mechanical Engineering, University of Texas at San Antonio, USA
| | - Anuradha Roy
- Department of Management Science and Statistics, University of Texas at San Antonio, USA
| | - Xiaodu Wang
- Department of Mechanical Engineering, University of Texas at San Antonio, USA.
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2
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Hui WH, Chen YL, Chang SW. Effects of aging and diabetes on the deformation mechanisms and molecular structural characteristics of collagen fibrils under daily activity. Int J Biol Macromol 2024; 254:127603. [PMID: 37871726 DOI: 10.1016/j.ijbiomac.2023.127603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 10/06/2023] [Accepted: 10/19/2023] [Indexed: 10/25/2023]
Abstract
Crosslinking plays an important role in collagen-based tissues since it affects mechanical behavior and tissue metabolism. Aging and diabetes affect the type and density of crosslinking, effectively altering tissue properties. However, most studies focus on these effects under large stress rather than daily activities. We focus on the deformation mechanisms and structural change at the binding sites for integrins, proteoglycans, and collagenase in collagen fibrils using a fully atomistic model. We show that high-connectivity enzymatic crosslinking (our "HC" model, representing normal tissues) and advanced-glycation end-products (our "Glucosepane" model, which increase in diabetes) result in uniform deformation under daily activity, but low-connectivity enzymatic crosslinking (our "LC" model, representing aging tissues) does not. In particular, the HC model displays more sliding, which may explain the ability of healthy tissues to absorb more strain energy. In contrast, AGEs induce instability in the structures near the binding sites, which would affect the tissue metabolism of the collagen molecule. Our results provide important insights into the molecular mechanisms of collagen and a possible explanation for the role of crosslinking in tissues undergoing daily activity.
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Affiliation(s)
- Wei-Han Hui
- Department of Civil Engineering, National Taiwan University, Taipei City, Taiwan
| | - Yen-Lin Chen
- Department of Civil Engineering, National Taiwan University, Taipei City, Taiwan
| | - Shu-Wei Chang
- Department of Civil Engineering, National Taiwan University, Taipei City, Taiwan; Department of Biomedical Engineering, National Taiwan University, Taipei City, Taiwan.
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3
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Batool S, Roth BJ, Xia Y. Depth-Dependent Strain Model (1D) for Anisotropic Fibrils in Articular Cartilage. MATERIALS (BASEL, SWITZERLAND) 2024; 17:238. [PMID: 38204091 PMCID: PMC10779946 DOI: 10.3390/ma17010238] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2023] [Revised: 12/21/2023] [Accepted: 12/29/2023] [Indexed: 01/12/2024]
Abstract
The mechanical response of articular cartilage (AC) under compression is anisotropic and depth-dependent. AC is osmotically active, and its intrinsic osmotic swelling pressure is balanced by its collagen fibril network. This mechanism requires the collagen fibers to be under a state of tensile pre-strain. A simple mathematical model is used to explain the depth-dependent strain calculations observed in articular cartilage under 1D axial compression (perpendicular to the articular surface). The collagen fibers are under pre-strain, influenced by proteoglycan concentration (fixed charged density, FCD) and collagen stiffness against swelling stress. The stiffness is introduced in our model as an anisotropic modulus that varies with fibril orientation through tissue depth. The collagen fibers are stiffer to stretching parallel to their length than perpendicular to it; when combined with depth-varying FCD, the model successfully predicts how tissue strains decrease with depth during compression. In summary, this model highlights that the mechanical properties of cartilage depend not only on proteoglycan concentration but also on the intrinsic properties of the pre-strained collagen network. These properties are essential for the proper functioning of articular cartilage.
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Affiliation(s)
| | - Bradley J. Roth
- Department of Physics, Oakland University, Rochester, MI 48309, USA; (S.B.); (Y.X.)
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4
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Bhattacharya S, Dubey DK. A multiscale investigation into the role of collagen-hyaluronan interface shear on the mechanical behaviour of collagen fibers in annulus fibrosus - Molecular dynamics-cohesive finite element-based study. J Mech Behav Biomed Mater 2023; 147:106147. [PMID: 37812947 DOI: 10.1016/j.jmbbm.2023.106147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Revised: 06/30/2023] [Accepted: 09/23/2023] [Indexed: 10/11/2023]
Abstract
Multi-directional deformation exhibited by annulus fibrosus (AF) is contributed by chemo-mechanical interactions among its biomolecular constituents' collagen type I (COL-I), collagen type II (COL-II), proteoglycans (aggrecan and hyaluronan) and water. However, the nature and role of such interactions on AF mechanics are unclear. This work employs a molecular dynamics-cohesive finite element-based multiscale approach to investigate role of COL-I-COL-II interchanging distribution and water concentration (WC) variations from outer annulus (OA) to inner annulus (IA) on collagen-hyaluronan (COL-HYL) interface shear, and the mechanisms by which interface shear impacts fibril sliding during collagen fiber deformation. At first, COL-HYL interface atomistic models are constructed by interchanging COL-I with COL-II and increasing COL-II and WC from 0 to 75%, and 65%-75% respectively. Thereafter, a multiscale approach is employed to develop representative volume elements (RVEs) of collagen fibers by incorporating COL-HYL shear as traction-separation behaviour at fibril-hyaluronan contact. Results show that increasing COL-II and WC increases interface stiffness from 0.6 GPa/nm to 1.2 GPa/nm and reduces interface strength from 155 MPa to 58 MPa from OA to IA, contributed by local hydration alterations. A stiffer and weaker interface enhances fibril sliding with increased straining at the contact - thereby contributing to reduction in modulus from 298 MPa to 198 MPa from OA to IA. Such reduction further contributes to softer mechanical response towards IA, as reported by earlier studies. Presented multiscale analysis provides deeper understanding of hierarchical structure-mechanics relationships in AF and can further aid in developing better substitutes for AF repair.
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Affiliation(s)
- Shambo Bhattacharya
- Department of Mechanical Engineering, Indian Institute of Technology Delhi, Haus Khas, New Delhi, 110016, India
| | - Devendra K Dubey
- Department of Mechanical Engineering, Indian Institute of Technology Delhi, Haus Khas, New Delhi, 110016, India.
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5
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Kamml J, Ke CY, Acevedo C, Kammer DS. The influence of AGEs and enzymatic cross-links on the mechanical properties of collagen fibrils. J Mech Behav Biomed Mater 2023; 143:105870. [PMID: 37156073 DOI: 10.1016/j.jmbbm.2023.105870] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 03/28/2023] [Accepted: 04/23/2023] [Indexed: 05/10/2023]
Abstract
Collagen, one of the main building blocks for various tissues, derives its mechanical properties directly from its structure of cross-linked tropocollagen molecules. The cross-links are considered to be a key component of collagen fibrils as they can change the fibrillar behavior in various ways. For instance, enzymatic cross-links (ECLs), one particular type of cross-links, are known for stabilizing the structure of the fibril and improving material properties, while cross-linking AGEs (Advanced-Glycation Endproducts) have been shown to accumulate and impair the mechanical properties of collageneous tissues. However, the reasons for whether and how a given type of cross-link improves or impairs the material properties remain unknown, and the exact relationship between the cross-link properties and density, and the fibrillar behavior is still not well understood. Here, we use coarse-grained steered molecular models to evaluate the effect of AGEs and ECLs cross-links content on the deformation and failure properties of collagen fibrils. Our simulations show that the collagen fibrils stiffen at high strain levels when the AGEs content exceeds a critical value. In addition, the strength of the fibril increases with AGEs accumulation. By analyzing the forces within the different types of cross-links (AGEs and ECLs) as well as their failure, we demonstrate that a change of deformation mechanism is at the origin of these observations. A high AGEs content reinforces force transfer through AGEs cross-links rather than through friction between sliding tropocollagen molecules, which leads to failure by breaking of bonds within the tropocollagen molecules. We show that this failure mechanism, which is associated with lower energy dissipation, results in more abrupt failure of the collagen fibril. Our results provide a direct and causal link between increased AGEs content, inhibited intra-fibrillar sliding, increased stiffness, and abrupt fibril fracture. Therefore, they explain the mechanical origin of bone brittleness as commonly observed in elderly and diabetic populations. Our findings contribute to a better understanding of the mechanisms underlying impaired tissue behavior due to elevated AGEs content and could enable targeted measures regarding the reduction of specific collagen cross-linking levels.
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Affiliation(s)
- Julia Kamml
- Institute for Building Materials, ETH Zurich, Switzerland
| | - Chun-Yu Ke
- Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, PA, USA
| | - Claire Acevedo
- Department of Mechanical Engineering, University of Utah, Salt Lake City, UT, USA; Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, USA
| | - David S Kammer
- Institute for Building Materials, ETH Zurich, Switzerland.
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6
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Yang F, Das D, Karunakaran K, Genin GM, Thomopoulos S, Chasiotis I. Nonlinear time-dependent mechanical behavior of mammalian collagen fibrils. Acta Biomater 2023; 163:63-77. [PMID: 35259515 PMCID: PMC9441475 DOI: 10.1016/j.actbio.2022.03.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2021] [Revised: 02/16/2022] [Accepted: 03/02/2022] [Indexed: 11/01/2022]
Abstract
The viscoelastic mechanical behavior of collagenous tissues has been studied extensively at the macroscale, yet a thorough quantitative understanding of the time-dependent mechanics of the basic building blocks of tissues, the collagen fibrils, is still missing. In order to address this knowledge gap, stress relaxation and creep tests at various stress (5-35 MPa) and strain (5-20%) levels were performed with individual collagen fibrils (average diameter of fully hydrated fibrils: 253 ± 21 nm) in phosphate buffered saline (PBS). The experimental results showed that the time-dependent mechanical behavior of fully hydrated individual collagen fibrils reconstituted from Type I calf skin collagen, is described by strain-dependent stress relaxation and stress-dependent creep functions in both the heel-toe and the linear regimes of deformation in monotonic stress-strain curves. The adaptive quasilinear viscoelastic (QLV) model, originally developed to capture the nonlinear viscoelastic response of collagenous tissues, provided a very good description of the nonlinear stress relaxation and creep behavior of the collagen fibrils. On the other hand, the nonlinear superposition (NSP) model fitted well the creep but not the stress relaxation data. The time constants and rates extracted from the adaptive QLV and the NSP models, respectively, pointed to a faster rate for stress relaxation than creep. This nonlinear viscoelastic behavior of individual collagen fibrils agrees with prior studies of macroscale collagenous tissues, thus demonstrating consistent time-dependent behavior across length scales and tissue hierarchies. STATEMENT OF SIGNIFICANCE: Pure stress relaxation and creep experiments were conducted for the first time with fully hydrated individual collagen fibrils. It is shown that collagen nanofibrils have a nonlinear time-dependent behavior which agrees with prior studies on macroscale collagenous tissues, thus demonstrating consistent time-dependent behavior across length scales and tissue hierarchies. This new insight into the non-linear viscoelastic behavior of the building blocks of mammalian collagenous tissues may serve as the foundation for improved macroscale tissue models that capture the mechanical behavior across length scales.
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Affiliation(s)
- Fan Yang
- Aerospace Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Debashish Das
- Aerospace Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Kathiresan Karunakaran
- Aerospace Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Guy M Genin
- Mechanical Engineering and Materials Science, Washington University, St. Louis, MO 63130, USA
| | - Stavros Thomopoulos
- Orthopedic Surgery, Biomedical Engineering, Columbia University, New York, NY 10032, USA
| | - Ioannis Chasiotis
- Aerospace Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
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7
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Pei Y, Yang W, Tang K, Kaplan DL. Collagen processing with mesoscale aggregates as templates and building blocks. Biotechnol Adv 2023; 63:108099. [PMID: 36649798 DOI: 10.1016/j.biotechadv.2023.108099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 01/11/2023] [Accepted: 01/11/2023] [Indexed: 01/15/2023]
Abstract
Collagen presents a well-organized hierarchical multilevel structure. Microfibers, fibers, and fiber bundles are the aggregates of natural collagen; which achieve an ideal balance of mechanical strength and toughness at the mesoscopic scale for biological tissue. These mesostructured aggregates of collagen isolated from biological tissues retain these inherent organizational features to enable their use as building blocks for constructing new collagen materials with ideal mechanical performance, thermal and dimensional stability. This strategy is distinct from the more common bottom-up or molecular-level design and assembly approach to generating collagen materials. The present review introduces the hierarchical structure of biological collagen with a focus on mesostructural features. Isolation strategies for these collagen aggregates (CAs) are summarized. Recent progress in the use of these mesostructural components for the construction of new collagen materials with emerging applications is reviewed, including in catalysis, environmental applications, biomedicine, food packaging, electrical energy storage, and flexible sensors. Finally, challenges and prospects are assessed for controllable production of CAs as well as material designs.
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Affiliation(s)
- Ying Pei
- College of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450001, China.
| | - Wen Yang
- Institute of Physics, Henan Academy of Sciences, Zhengzhou 450046, China
| | - Keyong Tang
- College of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450001, China.
| | - David L Kaplan
- Biomedical Engineering, Tufts University, MA 02155, United States
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8
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Unraveling the molecular mechanism of collagen flexibility during physiological warmup using molecular dynamics simulation and machine learning. Comput Struct Biotechnol J 2023; 21:1630-1638. [PMID: 36860343 PMCID: PMC9969283 DOI: 10.1016/j.csbj.2023.02.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2022] [Revised: 02/08/2023] [Accepted: 02/08/2023] [Indexed: 02/12/2023] Open
Abstract
Physiological warmup plays an important role in reducing the injury risk in different sports. In response to the associated temperature increase, the muscle and tendon soften and become easily stretched. In this study, we focused on type I collagen, the main component of the Achilles tendon, to unveil the molecular mechanism of collagen flexibility upon slight heating and to develop a model to predict the strain of collagen sequences. We used molecular dynamics approaches to simulate the molecular structures and mechanical behavior of the gap and overlap regions in type I collagen at 307 K, 310 K, and 313 K. The results showed that the molecular model in the overlap region is more sensitive to temperature increases. Upon increasing the temperature by 3 degrees Celsius, the end-to-end distance and Young's modulus of the overlap region decreased by 5% and 29.4%, respectively. The overlap region became more flexible than the gap region at higher temperatures. GAP-GPA and GNK-GSK triplets are critical for providing molecular flexibility upon heating. A machine learning model developed from the molecular dynamics simulation results showed good performance in predicting the strain of collagen sequences at a physiological warmup temperature. The strain-predictive model could be applied to future collagen designs to obtain desirable temperature-dependent mechanical properties.
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9
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Faisal TR, Adouni M, Dhaher YY. Surrogate modeling of articular cartilage degradation to understand the synergistic role of MMP-1 and MMP-9: a case study. Biomech Model Mechanobiol 2023; 22:43-56. [PMID: 36201069 DOI: 10.1007/s10237-022-01630-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Accepted: 08/22/2022] [Indexed: 11/26/2022]
Abstract
A characteristic feature of arthritic diseases is cartilage extracellular matrix (ECM) degradation, often orchestrated by the overexpression of matrix metalloproteinases (MMPs) and other proteases. The interplay between fibril level degradation and the tissue-level aggregate response to biomechanical loading was explored in this work by a computational multiscale cartilaginous model. We considered the relative abundance of collagenases (MMP-1) and gelatinases (MMP-9) in surrogate models, where the diffusion (spatial distribution) of these enzymes and the subsequent, co-localized fibrillar damage were spatially randomized with Latin Hypercube Sampling. The computational model was constructed by incorporating the results from prior molecular dynamics simulations (tensile test) of microfibril degradation into a hyper-elastoplastic fibril-reinforced cartilage model. Including MMPs-mediated collagen fibril-level degradation in computational models may help understand the ECM pathomechanics at the tissue level. The mechanics of cartilage tissue and fibril show variations in mechanical integrity depending on the different combinations of MMPs-1 and 9 with a concentration ratio of 1:1, 3:1, and 1:3 in simulated indentation tests. The fibril yield (local failure) was initiated at 20.2 ± 3.0 (%) and at 23.0 ± 2.8 (%) of bulk strain for col 1:gel 3 and col 3: gel 1, respectively. The reduction in failure stress (global response) was 39.8% for col 1:gel 3, 37.5% for col 1:gel 1, and 36.7% for col 3:gel 1 compared with the failure stress of the degradation free tissue. These findings indicate that cartilage's global and local mechanisms of failure largely depend on the relative abundance of the two key enzymes-collagenase (MMP-1) and gelatinase (MMP-9) and the spatial characteristics of diffusion across the layers of the cartilage ECM.
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Affiliation(s)
- Tanvir R Faisal
- Department of Mechanical Engineering, University of Louisiana at Lafayette, Lafayette, LA, 70508, USA.
| | - Malek Adouni
- Department of Mechanical Engineering, Australian College of Kuwait, East Mishref, Kuwait City, P.O. Box 1411, Kuwait
| | - Yasin Y Dhaher
- Department of Physical Medicine and Rehabilitation, University of Texas Southwest, Dallas, TX, USA
- Department of Orthopedic Surgery, University of Texas Southwest, Dallas, TX, USA
- Department of Biomedical Engineering, University of Texas Southwest, Dallas, TX, USA
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10
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Kamml J, Ke CY, Acevedo C, Kammer DS. The influence of AGEs and enzymatic cross-links on the mechanical properties of collagen fibrils. ARXIV 2023:arXiv:2301.13010v1. [PMID: 36776815 PMCID: PMC9915749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/14/2023]
Abstract
Cross-links are considered to be a key component of collagen fibrils as they can change the fibrillar behavior in various ways. Advanced-Glycation Endproducts (AGEs), one particular type of cross-links, have been shown to accumulate and impair the mechanical properties of collageneous tissues, whereas enzymatic cross-links (ECLs) are known for stabilizing the structure of the fibril. However, the reasons for whether a given type of cross-link improves or impairs the material properties remain unknown. Here, we use coarse-grained steered molecular models to evaluate the effect of AGEs and ECLs cross-links content on the deformation and failure properties of collagen fibrils. Our simulations show that the collagen fibrils stiffen at high strain levels when the AGEs content exceeds a critical value. In addition, the strength of the fibril increases with AGEs accumulation. By analyzing the forces within the different types of cross-links (AGEs and ECLs) as well as their failure, we demonstrate that a change of deformation mechanism is at the origin of these observations. A high AGEs content reinforces force transfer through AGEs cross-links rather than through friction between sliding tropocollagen molecules. We show that this failure mechanism, which is associated with lower energy dissipation, results in more abrupt failure of the collagen fibril. Our results provide a direct and causal link between increased AGEs content, inhibited intra-fibrillar sliding, increased stiffness, and abrupt fibril fracture. Therefore, they explain the mechanical origin of bone brittleness as commonly observed in elderly and diabetic populations. Our findings contribute to a better understanding of the mechanisms underlying impaired tissue behaviour due to elevated AGEs content and could enable targeted measures regarding the reduction of specific collagen cross-linking levels.
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Affiliation(s)
- Julia Kamml
- Institute for Building Materials, ETH Zurich, Switzerland
| | - Chun-Yu Ke
- Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, PA, USA
| | - Claire Acevedo
- Department of Mechanical Engineering, University of Utah, Salt Lake City, Utah, USA
- Department of Biomedical Engineering, University of Utah, Salt Lake City, Utah, USA
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11
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Rowe J, Röder K. Chemical bonds in collagen rupture selectively under tensile stress. Phys Chem Chem Phys 2023; 25:2331-2341. [PMID: 36597961 DOI: 10.1039/d2cp05051j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Collagen fibres are the main constituent of the extracellular matrix, and fulfil an important role in the structural stability of living multicellular organisms. An open question is how collagen absorbs pulling forces, and if the applied forces are strong enough to break bonds, what mechanisms underlie this process. As experimental studies on this topic are challenging, simulations are an important tool to further our understanding of these mechanisms. Here, we present pulling simulations of collagen triple helices, revealing the molecular mechanisms induced by tensile stress. At lower forces, pulling alters the configuration of proline residues leading to an effective absorption of applied stress. When forces are strong enough to introduce bond ruptures, these are located preferentially in X-position residues. Reduced backbone flexibility, for example through mutations or cross linking, weakens tensile resistance, leading to localised ruptures around these perturbations. In fibre-like segments, a significant overrepresentation of ruptures in proline residues compared to amino acid contents is observed. This study confirms the important role of proline in the structural stability of collagen, and adds detailed insight into the molecular mechanisms underlying this observation.
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Affiliation(s)
- James Rowe
- Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, UK.
| | - Konstantin Röder
- Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, UK.
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12
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Tavakol M, Vaughan TJ. A coarse-grained molecular dynamics investigation of the role of mineral arrangement on the mechanical properties of mineralized collagen fibrils. J R Soc Interface 2023; 20:20220803. [PMID: 36695019 PMCID: PMC9874270 DOI: 10.1098/rsif.2022.0803] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Accepted: 12/16/2022] [Indexed: 01/26/2023] Open
Abstract
Mineralized collagen fibrils (MCFs) comprise collagen molecules and hydroxyapatite (HAp) crystals and are considered universal building blocks of bone tissue, across different bone types and species. In this study, we developed a coarse-grained molecular dynamics (CGMD) framework to investigate the role of mineral arrangement on the load-deformation behaviour of MCFs. Despite the common belief that the collagen molecules are responsible for flexibility and HAp minerals are responsible for stiffness, our results showed that the mineral phase was responsible for limiting collagen sliding in the large deformation regime, which helped the collagen molecules themselves undergo high tensile loading, providing a substantial contribution to the ultimate tensile strength of MCFs. This study also highlights different roles for the mineralized and non-mineralized protofibrils within the MCF, with the mineralized groups being primarily responsible for load carrying due to the presence of the mineral phase, while the non-mineralized groups are responsible for crack deflection. These results provide novel insight into the load-deformation behaviour of MCFs and highlight the intricate role that both collagen and mineral components have in dictating higher scale bone biomechanics.
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Affiliation(s)
- Mahdi Tavakol
- Biomedical Engineering and Biomechanics Research Centre, School of Engineering, College of Science and Engineering, University of Galway, Galway, Ireland
| | - Ted J. Vaughan
- Biomedical Engineering and Biomechanics Research Centre, School of Engineering, College of Science and Engineering, University of Galway, Galway, Ireland
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13
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Andriotis OG, Nalbach M, Thurner PJ. Mechanics of isolated individual collagen fibrils. Acta Biomater 2022; 163:35-49. [PMID: 36509398 DOI: 10.1016/j.actbio.2022.12.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 11/15/2022] [Accepted: 12/05/2022] [Indexed: 12/13/2022]
Abstract
Collagen fibrils are the fundamental structural elements in vertebrate animals and compose a framework that provides mechanical support to load-bearing tissues. Understanding how these fibrils initially form and mechanically function has been the focus of a myriad of detailed investigations over the last few decades. From these studies a great amount of knowledge has been acquired as well as a number of new questions to consider. In this review, we examine the current state of our knowledge of the mechanical properties of extant fibrils. We emphasize on the mechanical response and related deformation of collagen fibrils upon tension, which is the predominant load imposed in most collagen-rich tissues. We also illuminate the gaps in knowledge originating from the intriguing results that the field is still trying to interpret. STATEMENT OF SIGNIFICANCE: : Collagen is the result of millions of years of biological evolution and is a unique family of proteins, the majority of which provide mechanical support to biological tissues. Cells produce collagen molecules that self-assemble into larger structures, known as collagen fibrils. As simple as they appear under an optical microscope, collagen fibrils display a complex ultrastructural architecture tuned to the external forces that are imposed upon them. Even more complex is the way collagen fibrils deform under loading, and the nature of the mechanisms that drive their formation in the first place. Here, we present a cogent synthesis of the state-of-knowledge of collagen fibril mechanics. We focus on the information we have from in vitro experiments on individual, isolated from tissues, collagen fibrils and the knowledge available from in silico tests.
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Affiliation(s)
- Orestis G Andriotis
- Institute for Lightweight Design and Structural Biomechanics, TU Wien, Vienna, A-1060, Austria
| | - Mathis Nalbach
- Institute for Lightweight Design and Structural Biomechanics, TU Wien, Vienna, A-1060, Austria
| | - Philipp J Thurner
- Institute for Lightweight Design and Structural Biomechanics, TU Wien, Vienna, A-1060, Austria.
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14
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Szarek P, Pierce DM. A specialized protocol for mechanical testing of isolated networks of type II collagen. J Mech Behav Biomed Mater 2022; 136:105466. [PMID: 36183667 DOI: 10.1016/j.jmbbm.2022.105466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 09/09/2022] [Accepted: 09/11/2022] [Indexed: 11/24/2022]
Abstract
The mechanical responses of most soft biological tissues rely heavily on networks of collagen fibers, thus quantifying the mechanics of both individual collagen fibers and networks of these fibers advances understanding of biological tissues in health and disease. The mechanics of type I collagen are well-studied and quantified. Yet no data exist on the tensile mechanical responses of individual type II collagen fibers nor of isolated networks comprised of type II collagen. We aimed to establish methods to facilitate studies of networked and individual type II collagen fibers within the native networked structure, specifically to establish best practices for isolating and mechanically testing type II collagen networks in tension. We systematically investigated mechanical tests of networks of type II collagen undergoing uniaxial extension, and quantified ranges for each of the important variables to help ensure that the experiment itself does not affect the measured mechanical parameters. Specifically we determined both the specimen (establishing networks of isolated collagen, the footprint and thickness of the specimen) and the mechanical test (both the device and the strain rate) to establish a repeatable and practical protocol. Mechanical testing of isolated networks of type II collagen fibers leveraging this protocol will lead to better understanding of the mechanics both of these networks and of the individual fibers. Such understanding may aid in developing and testing therapeutics, understanding inter-constituent interactions (and their roles in bulk-tissue biomechanics), investigating mechanical/biochemical modifications to networked type II collagen, and proposing, calibrating, and validating constitutive models for finite element analyses.
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Affiliation(s)
- Phoebe Szarek
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT, United States of America
| | - David M Pierce
- Department of Biomedical Engineering, University of Connecticut, Storrs, CT, United States of America; Department of Mechanical Engineering, University of Connecticut, Storrs, CT, United States of America.
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15
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Collagen-Based Biomimetic Systems to Study the Biophysical Tumour Microenvironment. Cancers (Basel) 2022; 14:cancers14235939. [PMID: 36497421 PMCID: PMC9739814 DOI: 10.3390/cancers14235939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 11/22/2022] [Accepted: 11/26/2022] [Indexed: 12/03/2022] Open
Abstract
The extracellular matrix (ECM) is a pericellular network of proteins and other molecules that provides mechanical support to organs and tissues. ECM biophysical properties such as topography, elasticity and porosity strongly influence cell proliferation, differentiation and migration. The cell's perception of the biophysical microenvironment (mechanosensing) leads to altered gene expression or contractility status (mechanotransduction). Mechanosensing and mechanotransduction have profound implications in both tissue homeostasis and cancer. Many solid tumours are surrounded by a dense and aberrant ECM that disturbs normal cell functions and makes certain areas of the tumour inaccessible to therapeutic drugs. Understanding the cell-ECM interplay may therefore lead to novel and more effective therapies. Controllable and reproducible cell culturing systems mimicking the ECM enable detailed investigation of mechanosensing and mechanotransduction pathways. Here, we discuss ECM biomimetic systems. Mainly focusing on collagen, we compare and contrast structural and molecular complexity as well as biophysical properties of simple 2D substrates, 3D fibrillar collagen gels, cell-derived matrices and complex decellularized organs. Finally, we emphasize how the integration of advanced methodologies and computational methods with collagen-based biomimetics will improve the design of novel therapies aimed at targeting the biophysical and mechanical features of the tumour ECM to increase therapy efficacy.
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16
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Moo EK, Ebrahimi M, Sibole SC, Tanska P, Korhonen RK. The intrinsic quality of proteoglycans, but not collagen fibres, degrades in osteoarthritic cartilage. Acta Biomater 2022; 153:178-189. [PMID: 36113721 DOI: 10.1016/j.actbio.2022.09.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 08/31/2022] [Accepted: 09/02/2022] [Indexed: 11/01/2022]
Abstract
The function of articular cartilage as a load-bearing connective tissue is derived primarily from a balanced interaction between the swelling proteoglycan (PG) matrix and tension-resistant collagen fibrous network. Such balance is compromised during joint disease such as osteoarthritis (OA) due to degradation to PGs and/or collagens. While the PG degradation is generally thought to be related to a loss of protein abundance, the collagenous degradation is more complex as it can be caused independently by a decrease of collagen content, disorganisation of fibrous structure and softening of individual collagen fibrils. A comprehensive understanding of the initial trajectories of degradation of PGs and collagen network can improve our chance of finding potential therapeutic solutions for OA. Here, we developed geometrically, structurally, and compositionally realistic and sample-specific Finite Element (FE) models under the framework of multiphasic mixture theory, from which the elastic moduli of collagen fibres and the PG load-bearing quality in healthy and diseased cartilages were estimated by numerical optimisation of the multi-step indentation stress relaxation force-time curves. We found the intrinsic quality of collagen fibres, measured by their elastic moduli, to stay constant for healthy and diseased cartilages. Combining with previous findings which show unaltered collagen content during early stages of OA, our results suggest the disorganisation of collagen fibrous network as the first form of collagenous degradation in osteoarthritic cartilage. We also found that PG degradation involves not only a loss of protein abundance, but also the quality of the remaining PGs in generating sufficient osmotic pressure for load bearing. This study sheds light on the mechanism of OA pathogenesis and highlights the restoration of collageneous organisation in cartilage as key medical intervention for OA. STATEMENT OF SIGNIFICANCE: Collagen network in articular cartilage consists of individual fibres that are organised into depth-dependent structure specialised for joint load-bearing and lubrication. During osteoarthritis, the collagen network undergoes mechanical degradation, but it is unclear if a loss of content, disorganisation of fibrous structure, or softening of individual fibres causes this degeneration. Using mechanical indentation, Finite Element modelling, and numerical optimisation methods, we determined that individual fibres did not soften in early disease stage. Together with previous findings showing unaltered collagen content, our results pinpoint the disorganisation of collagen structure as the main culprit for early collagenous degradation in osteoarthritic cartilage. Thus, early restoration in cartilage of collagen organisation, instead of individual fibre quality, may be key to slow osteoarthritis development.
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Affiliation(s)
- Eng Kuan Moo
- Department of Applied Physics, University of Eastern Finland, POB 1627, Kuopio 70211, Finland; Human Performance Laboratory, University of Calgary, 2500, University Drive NW, Calgary, Alberta 2N1N4, Canada.
| | | | - Scott C Sibole
- Human Performance Laboratory, University of Calgary, 2500, University Drive NW, Calgary, Alberta 2N1N4, Canada
| | - Petri Tanska
- Department of Applied Physics, University of Eastern Finland, POB 1627, Kuopio 70211, Finland
| | - Rami K Korhonen
- Department of Applied Physics, University of Eastern Finland, POB 1627, Kuopio 70211, Finland.
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17
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Zhai C, Sullivan PA, Martin CL, Shi H, Deravi LF, Yeo J. Probing the alignment-dependent mechanical behaviors and time-evolutional aligning process of collagen scaffolds. J Mater Chem B 2022; 10:7052-7061. [PMID: 36047129 DOI: 10.1039/d2tb01360f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Efficiently manipulating and reproducing collagen (COL) alignment in vitro remains challenging because many of the fundamental mechanisms underlying and guiding the alignment process are not known. We reconcile experiments and coarse-grained molecular dynamics simulations to investigate the mechanical behaviors of a growing COL scaffold and assay how changes in fiber alignment and various cross-linking densities impact their alignment dynamics under shear flow. We find higher cross-link densities and alignment levels significantly enhance the apparent tensile/shear moduli and strength of a bulk COL system, suggesting potential measures to facilitate the design of stronger COL based materials. Since fibril alignment plays a key factor in scaffold mechanics, we next investigate the molecular mechanism behind fibril alignment with Couette flow by computationally investigating the effects of COL's structural properties such as chain lengths, number of chains, tethering conditions, and initial COL conformations on the COL's final alignment level. Our computations suggest that longer chain lengths, more chains, greater amounts of tethering, and initial anisotropic COL conformations benefit the final alignment, but the effect of chain lengths may be more dominant over other factors. These results provide important parameters for consideration in manufacturing COL-based scaffolds where alignment and cross-linking are necessary for regulating performance.
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Affiliation(s)
- Chenxi Zhai
- J2 Lab for Engineering Living Materials, Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY, 14853, USA.
| | - Patrick A Sullivan
- Department of Chemistry and Chemical Biology, Northeastern University, 360 Huntington Avenue, Boston, MA 02115, USA
| | - Cassandra L Martin
- Department of Chemistry and Chemical Biology, Northeastern University, 360 Huntington Avenue, Boston, MA 02115, USA
| | - Haoyuan Shi
- J2 Lab for Engineering Living Materials, Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY, 14853, USA.
| | - Leila F Deravi
- Department of Chemistry and Chemical Biology, Northeastern University, 360 Huntington Avenue, Boston, MA 02115, USA
| | - Jingjie Yeo
- J2 Lab for Engineering Living Materials, Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY, 14853, USA.
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18
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Prior C, Panter J, Kusumaatmaja H. A minimal model of elastic instabilities in biological filament bundles. JOURNAL OF THE ROYAL SOCIETY, INTERFACE 2022; 19:20220287. [PMID: 36128703 PMCID: PMC9490347 DOI: 10.1098/rsif.2022.0287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
We present a model of a system of elastic fibres which exhibits complex, coupled, nonlinear deformations via a connecting elastic spring network. This model can capture physically observed deformations such as global buckling, pinching and internal collapse. We explore the transitions between these deformation modes numerically, using an energy minimization approach, highlighting how supported environments, or stiff outer sheath structures, favour internal structural collapse over global deformation. We then derive a novel analytic buckling criterion for the internal collapse of the system, a mode of structural collapse pertinent in many biological filament bundles such as the optic nerve bundle and microtubule bundles involved in cell abscission.
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Affiliation(s)
- Chris Prior
- Department of Mathematical Sciences, Durham University, Durham DH1 3LE, UK
| | - Jack Panter
- Department of Physics, Durham University, Durham DH1 3LE, UK
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19
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Tian X, Zhao K, Teng A, Li Y, Wang W. A rethinking of collagen as tough biomaterials in meat packaging: assembly from native to synthetic. Crit Rev Food Sci Nutr 2022; 64:957-977. [PMID: 35997287 DOI: 10.1080/10408398.2022.2111401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Due to the high moisture-associated typical rheology and the changeable and harsh processing conditions in the production process, packaging materials for meat products have higher requirements including a sufficient mechanical strength and proper ductility. Collagen, a highly conserved structural protein consisting of a triple helix of Gly-X-Y repeats, has been proved to be suitable packaging material for meat products. The treated animal digestive tract (i.e. the casing) is the perfect natural packaging material for wrapping meat into sausage. Its thin walls, strong toughness and impact resistance make it the oldest and best edible meat packaging. Collagen casing is another wisdom of meat packaging, which is made by collagen fibers from hide skin, presenting a rapid growth in casing market. To strengthen mechanical strength and barrier behaviors of collagen-based packaging materials, different physical, chemical, and biological cross-linking methods are springing up exuberantly, as well as a variety of reinforcement approaches including nanotechnology. In addition, the rapid development of biomimetic technology also provides a good research idea and means for the promotion of collagen's assembly and relevant mechanical properties. This review can offer some reference on fundamental theory and practical application of collagenous materials in meat products.
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Affiliation(s)
- Xiaojing Tian
- College of Food Science and Engineering, Tianjin University of Science & Technology, Tianjin, China
| | - KaiXuan Zhao
- College of Food Science and Engineering, Tianjin University of Science & Technology, Tianjin, China
| | - Anguo Teng
- College of Food Science and Engineering, Tianjin University of Science & Technology, Tianjin, China
| | - Yu Li
- College of Biotechnology, Tianjin University of Science & Technology, Tianjin, China
| | - Wenhang Wang
- College of Food Science and Engineering, Tianjin University of Science & Technology, Tianjin, China
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20
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Gachon E, Mesquida P. Mechanical properties of collagen fibrils determined by buckling analysis. Acta Biomater 2022; 149:60-68. [PMID: 35803503 DOI: 10.1016/j.actbio.2022.06.044] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 06/25/2022] [Accepted: 06/28/2022] [Indexed: 11/16/2022]
Abstract
The mechanical properties of biological nanofibers such as collagen fibrils are important in many applications, ranging from tissue-engineering to cancer treatment. However, mechanical testing is not straightforward at the nanometer scale. Here, we use the theory of column-buckling to determine the bending properties of individual collagen fibrils. To achieve this, fibrils were deposited on a manually pre-stretched foil, which was then released with the fibrils attached. Atomic Force Microscopy (AFM) imaging was used to determine the tensile modulus by measuring the buckling-wavelength and the radius for each fibril. Comparison with data obtained by AFM nanoindentation and other, more sophisticated methods, shows that our results are in very good agreement. The great advantage of this simple approach is that it can be used to quickly determine mechanical properties without force or stress-strain measurements, which are challenging to obtain accurately and at high throughput at the nanoscale. The method could be applied to any nanofibers, not just collagen fibrils. STATEMENT OF SIGNIFICANCE: Collagen fibrils are the main constituent of the extracellular matrix, and alterations of their mechanical properties can have significant effects on cell adhesion and motility. This has, ultimately, implications in age-related diseases and cancer. Furthermore, tuning the mechanical properties of collagen fibrils could be an important tool in the design of artificial cell scaffolds in tissue-engineering. For these reasons, it is important to have methods that can be used to determine the mechanical properties of fibrils at the single-fibril level and, therefore, at the nanometer scale. The method presented here has the advantage of being easy to use and avoids some of the fundamental issues of more established methods.
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Affiliation(s)
- Emilie Gachon
- Department of Physics, King's College London, Strand, London WC2R 2LS, United Kingdom
| | - Patrick Mesquida
- Department of Physics, King's College London, Strand, London WC2R 2LS, United Kingdom.
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21
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Gouissem A, Mbarki R, Al Khatib F, Adouni M. Multiscale Characterization of Type I Collagen Fibril Stress–Strain Behavior under Tensile Load: Analytical vs. MD Approaches. Bioengineering (Basel) 2022; 9:bioengineering9050193. [PMID: 35621471 PMCID: PMC9138028 DOI: 10.3390/bioengineering9050193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 04/17/2022] [Accepted: 04/26/2022] [Indexed: 11/24/2022] Open
Abstract
Type I collagen is one of the most important proteins in the human body because of its role in providing structural support to the extracellular matrix of the connective tissues. Understanding its mechanical properties was widely investigated using experimental testing as well as molecular and finite element simulations. In this work, we present a new approach for defining the properties of the type I collagen fibrils by analytically formulating its response when subjected to a tensile load and investigating the effects of enzymatic crosslinks on the behavioral response. We reveal some of the shortcomings of the molecular dynamics (MD) method and how they affect the obtained stress–strain behavior of the fibril, and we prove that not only does MD underestimate the Young’s modulus and the ultimate tensile strength of the collagen fibrils, but also fails to detect the mechanics of some stretching phases of the fibril. We prove that non-crosslinked fibrils have three tension phases: (i) an initial elastic deformation corresponding to the collagen molecule uncoiling, (ii) a linear regime related to the stretching of the backbone of the tropocollagen molecules, and (iii) a plastic regime dominated by molecular sliding. We also show that for crosslinked fibrils, the second regime can be subdivided into three sub-regimes, and we define the properties of each regime. We also prove, analytically, the alleged MD quadratic relation between the ultimate tensile strength of the fibril and the concentration of enzymatic crosslinks (β).
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Affiliation(s)
- Afif Gouissem
- Mechanical Engineering Department, Australian University, East Mishref, Kuwait City P.O. Box 1411, Kuwait; (A.G.); (R.M.); (F.A.K.)
| | - Raouf Mbarki
- Mechanical Engineering Department, Australian University, East Mishref, Kuwait City P.O. Box 1411, Kuwait; (A.G.); (R.M.); (F.A.K.)
| | - Fadi Al Khatib
- Mechanical Engineering Department, Australian University, East Mishref, Kuwait City P.O. Box 1411, Kuwait; (A.G.); (R.M.); (F.A.K.)
| | - Malek Adouni
- Mechanical Engineering Department, Australian University, East Mishref, Kuwait City P.O. Box 1411, Kuwait; (A.G.); (R.M.); (F.A.K.)
- Physical Medicine and Rehabilitation Department, Northwestern University, Chicago, IL 60611, USA
- Correspondence:
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22
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Atomic Force Microscopy Nanoindentation Method on Collagen Fibrils. MATERIALS 2022; 15:ma15072477. [PMID: 35407813 PMCID: PMC8999528 DOI: 10.3390/ma15072477] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/15/2022] [Revised: 03/20/2022] [Accepted: 03/24/2022] [Indexed: 12/24/2022]
Abstract
Atomic Force Microscopy nanoindentation method is a powerful technique that can be used for the nano-mechanical characterization of bio-samples. Significant scientific efforts have been performed during the last two decades to accurately determine the Young’s modulus of collagen fibrils at the nanoscale, as it has been proven that mechanical alterations of collagen are related to various pathological conditions. Different contact mechanics models have been proposed for processing the force–indentation data based on assumptions regarding the shape of the indenter and collagen fibrils and on the elastic or elastic–plastic contact assumption. However, the results reported in the literature do not always agree; for example, the Young’s modulus values for dry collagen fibrils expand from 0.9 to 11.5 GPa. The most significant parameters for the broad range of values are related to the heterogeneous structure of the fibrils, the water content within the fibrils, the data processing errors, and the uncertainties in the calibration of the probe. An extensive discussion regarding the models arising from contact mechanics and the results provided in the literature is presented, while new approaches with respect to future research are proposed.
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23
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Zhang Y, Hollis D, Ross R, Snow T, Terrill NJ, Lu Y, Wang W, Connelly J, Tozzi G, Gupta HS. Investigating the Fibrillar Ultrastructure and Mechanics in Keloid Scars Using In Situ Synchrotron X-ray Nanomechanical Imaging. MATERIALS 2022; 15:ma15051836. [PMID: 35269067 PMCID: PMC8911729 DOI: 10.3390/ma15051836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 10/24/2021] [Accepted: 01/21/2022] [Indexed: 12/10/2022]
Abstract
Fibrotic scarring is prevalent in a range of collagenous tissue disorders. Understanding the role of matrix biophysics in contributing to fibrotic progression is important to develop therapies, as well as to elucidate biological mechanisms. Here, we demonstrate how microfocus small-angle X-ray scattering (SAXS), with in situ mechanics and correlative imaging, can provide quantitative and position-resolved information on the fibrotic matrix nanostructure and its mechanical properties. We use as an example the case of keloid scarring in skin. SAXS mapping reveals heterogeneous gradients in collagen fibrillar concentration, fibril pre-strain (variations in D-period) and a new interfibrillar component likely linked to proteoglycans, indicating evidence of a complex 3D structure at the nanoscale. Furthermore, we demonstrate a proof-of-principle for a diffraction-contrast correlative imaging technique, incorporating, for the first time, DIC and SAXS, and providing an initial estimate for measuring spatially resolved fibrillar-level strain and reorientation in such heterogeneous tissues. By application of the method, we quantify (at the microscale) fibrillar reorientations, increases in fibrillar D-period variance, and increases in mean D-period under macroscopic tissue strains of ~20%. Our results open the opportunity of using synchrotron X-ray nanomechanical imaging as a quantitative tool to probe structure–function relations in keloid and other fibrotic disorders in situ.
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Affiliation(s)
- Yuezhou Zhang
- Institute of Bioengineering and School of Engineering and Materials Science, Queen Mary University of London, London E1 4NS, UK; (Y.Z.); (W.W.)
| | - Dave Hollis
- LaVision UK, 2 Minton Place, Victoria Road, Bicester OX26 6QB, UK;
| | - Rosie Ross
- Centre for Cell Biology and Cutaneous Research, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London E1 2AT, UK; (R.R.); (J.C.)
| | - Tim Snow
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, UK; (T.S.); (N.J.T.)
| | - Nick J. Terrill
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, UK; (T.S.); (N.J.T.)
| | - Yongjie Lu
- Centre for Biomarkers and Biotherapeutics, Barts Cancer Institute, Queen Mary University of London, John Vane Science Centre, Charterhouse Square, London EC1M 5PZ, UK;
| | - Wen Wang
- Institute of Bioengineering and School of Engineering and Materials Science, Queen Mary University of London, London E1 4NS, UK; (Y.Z.); (W.W.)
| | - John Connelly
- Centre for Cell Biology and Cutaneous Research, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London E1 2AT, UK; (R.R.); (J.C.)
| | - Gianluca Tozzi
- School of Engineering, London South Bank University, London SE1 0AA, UK;
| | - Himadri S. Gupta
- Institute of Bioengineering and School of Engineering and Materials Science, Queen Mary University of London, London E1 4NS, UK; (Y.Z.); (W.W.)
- Correspondence:
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24
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Yang F, Das D, Chasiotis I. Microscale Creep and Stress Relaxation Experiments with Individual Collagen Fibrils. OPTICS AND LASERS IN ENGINEERING 2022; 150:106869. [PMID: 35027783 PMCID: PMC8752082 DOI: 10.1016/j.optlaseng.2021.106869] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Nanoscale macromolecular biological structures exhibit time-dependent behavior, yet a quantitative understanding of their time-dependent mechanical behavior remains elusive, largely due to experimental challenges in attaining sufficient spatial and temporal resolution and control of stress or strain in conditions that guarantee their molecular integrity. To address this gap, an experimental methodology was developed to conduct creep and stress relaxation experiments with individual mammalian collagen fibrils. An image-based edge detection method implemented with high magnification optical microscopy and combined with closed-loop proportional-integral-derivative (PID) control was implemented and calibrated to apply constant force or stretch ratio values to individual collagen fibrils via a Microelectromechanical Systems (MEMS) device. This experimental methodology allowed for real-time control of uniaxial tensile stress or strain with 27 nm displacement resolution. The overall experimental system was tuned to apply step inputs with rise times below 0.5 s, less than 2.5% overshoot, and steady-state error less than 0.5%. Three individual collagen fibrils with diameters 101-121 nm were subjected to creep and stress relaxation tests in the range 4-20% engineering strain, under partially hydrated conditions. The collagen fibrils demonstrated non-linear viscoelastic behavior that was described well by the adaptive quasi-linear viscoelastic model. The results of this study demonstrate for the first time that mammalian collagen fibrils, the building blocks of connective tissues, exhibit nonlinear viscoelastic behavior in their partially hydrated state.
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Affiliation(s)
- Fan Yang
- Aerospace Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Debashish Das
- Aerospace Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Ioannis Chasiotis
- Aerospace Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA
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25
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Mouss MEL, Merzouki T, Rekik A, Hambli R. Multiscale approach incorporating tropocollagen scale to assess the effect of molecular age-related modifications on elastic constants of cortical bone based on finite element and homogenization methods. J Mech Behav Biomed Mater 2022; 128:105130. [DOI: 10.1016/j.jmbbm.2022.105130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 12/15/2021] [Accepted: 02/10/2022] [Indexed: 10/19/2022]
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26
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Kumemura M, Pekin D, Menon VA, Van Seuningen I, Collard D, Tarhan MC. Fabricating Silicon Resonators for Analysing Biological Samples. MICROMACHINES 2021; 12:1546. [PMID: 34945396 PMCID: PMC8708134 DOI: 10.3390/mi12121546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Revised: 12/08/2021] [Accepted: 12/10/2021] [Indexed: 11/17/2022]
Abstract
The adaptability of microscale devices allows microtechnologies to be used for a wide range of applications. Biology and medicine are among those fields that, in recent decades, have applied microtechnologies to achieve new and improved functionality. However, despite their ability to achieve assay sensitivities that rival or exceed conventional standards, silicon-based microelectromechanical systems remain underutilised for biological and biomedical applications. Although microelectromechanical resonators and actuators do not always exhibit optimal performance in liquid due to electrical double layer formation and high damping, these issues have been solved with some innovative fabrication processes or alternative experimental approaches. This paper focuses on several examples of silicon-based resonating devices with a brief look at their fundamental sensing elements and key fabrication steps, as well as current and potential biological/biomedical applications.
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Affiliation(s)
- Momoko Kumemura
- Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, 2-4 Hibikino, Wakamatsu-ku, Kitakyushu-shi, Fukuoka 808-0196, Japan;
- LIMMS/CNRS-IIS, Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan; (D.P.); (D.C.)
| | - Deniz Pekin
- LIMMS/CNRS-IIS, Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan; (D.P.); (D.C.)
- CNRS/IIS/COL/Lille University, SMMiL-E Project, CNRS Délégation Nord-Pas de Calais et Picardie, 2 rue de Canonniers, CEDEX, 59046 Lille, France
- Univ. Lille, CNRS, Inserm, CHU Lille, UMR9020-U1277—CANTHER—Cancer Heterogeneity Plasticity and Resistance to Therapies, F-59000 Lille, France;
| | - Vivek Anand Menon
- Division of Mechanical Science and Technology, Gunma University, 1-5-1 Tenjin-cho, Kiryu-shi, Gunma 376-8515, Japan;
| | - Isabelle Van Seuningen
- Univ. Lille, CNRS, Inserm, CHU Lille, UMR9020-U1277—CANTHER—Cancer Heterogeneity Plasticity and Resistance to Therapies, F-59000 Lille, France;
| | - Dominique Collard
- LIMMS/CNRS-IIS, Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan; (D.P.); (D.C.)
- CNRS/IIS/COL/Lille University, SMMiL-E Project, CNRS Délégation Nord-Pas de Calais et Picardie, 2 rue de Canonniers, CEDEX, 59046 Lille, France
| | - Mehmet Cagatay Tarhan
- LIMMS/CNRS-IIS, Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan; (D.P.); (D.C.)
- CNRS/IIS/COL/Lille University, SMMiL-E Project, CNRS Délégation Nord-Pas de Calais et Picardie, 2 rue de Canonniers, CEDEX, 59046 Lille, France
- Univ. Lille, CNRS, Centrale Lille, Junia, University Polytechnique Hauts-de-France, UMR 8520—IEMN, Institut
d’Electronique de Microélectronique et de Nanotechnologie, F-59000 Lille, France
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Reversible changes in the 3D collagen fibril architecture during cyclic loading of healthy and degraded cartilage. Acta Biomater 2021; 136:314-326. [PMID: 34563724 PMCID: PMC8631461 DOI: 10.1016/j.actbio.2021.09.037] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 08/19/2021] [Accepted: 09/20/2021] [Indexed: 01/09/2023]
Abstract
Biomechanical changes to the collagen fibrillar architecture in articular cartilage are believed to play a crucial role in enabling normal joint function. However, experimentally there is little quantitative knowledge about the structural response of the Type II collagen fibrils in cartilage to cyclic loading in situ, and the mechanisms that drive the ability of cartilage to withstand long-term repetitive loading. Here we utilize synchrotron small-angle X-ray scattering (SAXS) combined with in-situ cyclic loading of bovine articular cartilage explants to measure the fibrillar response in deep zone articular cartilage, in terms of orientation, fibrillar strain and inter-fibrillar variability in healthy cartilage and cartilage degraded by exposure to the pro-inflammatory cytokine IL-1β. We demonstrate that under repeated cyclic loading the fibrils reversibly change the width of the fibrillar orientation distribution whilst maintaining a largely consistent average direction of orientation. Specifically, the effect on the fibrillar network is a 3-dimensional conical orientation broadening around the normal to the joint surface, inferred by 3D reconstruction of X-ray scattering peak intensity distributions from the 2D pattern. Further, at the intrafibrillar level, this effect is coupled with reversible reduction in fibrillar pre-strain under compression, alongside increase in the variability of fibrillar pre-strain. In IL-1β degraded cartilage, the collagen rearrangement under cyclic loading is disrupted and associated with reduced tissue stiffness. These finding have implications as to how changes in local collagen nanomechanics might drive disease progression or vice versa in conditions such as osteoarthritis and provides a pathway to a mechanistic understanding of such diseases. Statement of significance Structural deterioration in biomechanically loaded musculoskeletal organs, e.g., joint osteoarthritis and back pain, are linked to breakdown and changes in their collagen-rich cartilaginous tissue matrix. A critical component enabling cartilage biomechanics is the ultrastructural collagen fibrillar network in cartilage. However, experimental probes of the dynamic structural response of cartilage collagen to biomechanical loads are limited. Here, we use X-ray scattering during cyclic loading (as during walking) on joint tissue to show that cartilage fibrils resist loading by a reversible, three-dimensional orientation broadening and disordering mechanism at the molecular level, and that inflammation reduces this functionality. Our results will help understand how changes to small-scale tissue mechanisms are linked to ageing and osteoarthritic progression, and development of biomaterials for joint replacements.
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Rawal A, Rhinehardt KL, Mohan RV, Pendse M. Influence of Hydroxyproline on Mechanical Behavior of Collagen Mimetic Proteins Under Fraying Deformation-Molecular Dynamics Investigations. J Biomech Eng 2021; 143:1105248. [PMID: 33764409 DOI: 10.1115/1.4050648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Indexed: 11/08/2022]
Abstract
Molecular dynamics modeling is used to simulate, model, and analyze mechanical deformation behavior and predictive properties of three different synthetic collagen proteins obtained from RSC-PDB, 1BKV, 3A08, and 2CUO, with varying concentrations of hydroxyproline (HYP). Hydroxyproline is credited with providing structural support for the collagen protein molecules. Hydroxyproline's influence on these three synthetic collagen proteins' mechanical deformation behavior and predictive properties is investigated in this paper. A detailed study and inference of the protein's mechanical characteristics associated with HYP content are investigated through fraying deformation behavior. A calculated Gibbs free energy value (ΔG) of each polypeptide α chain that corresponds with a complete unfolding of a single polypeptide α-chain from a triple-helical protein is obtained with umbrella sampling. The force needed for complete separation of the polypeptide α-chain from the triple-helical protein is analyzed for proteins to understand the influence of HYP concentration and is discussed in this paper. Along with a difference in ΔG, different unfolding pathways for the molecule and individual chains are observed. The correlation between the fraying deformation mechanical characteristics and the collagen proteins' hydroxyproline content is provided in this study via the three collagen proteins' resulting binding energies.
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Affiliation(s)
- Atul Rawal
- Nanoengineering Department, Joint School of Nanoscience and Nanoengineering, North Carolina A&T State University, Greensboro, NC 27401
| | - Kristen L Rhinehardt
- Computational Data Science and Engineering Department, North Carolina A&T State University, Greensboro, NC 27401
| | - Ram V Mohan
- Nanoengineering Department, Joint School of Nanoscience and Nanoengineering, North Carolina A&T State University, Greensboro, NC 27401
| | - Max Pendse
- Nanoengineering Department, Joint School of Nanoscience and Nanoengineering, North Carolina A&T State University, Greensboro, NC 27401
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Abstract
Studying changes in collagen deformation behavior at the nanoscale due to variations in mineralization and hydration is important for characterizing and developing collagen-based bio-composites. Recent studies also find that carbon nanotubes (CNTs) show promise as a reinforcing material for collagenous bio-composites. Currently, the effects of variation in mineral, water, and CNT content on collagen gap and overlap region mechanics during compression is unexplored. We use molecular dynamics simulations to investigate how variations in mineral, water, and CNT contents of collagen bio-composites in compression change their deformation behavior and thermal properties. Results indicate that variations in mineral and water content affect the collagen structure due to expansion or contraction of the gap and overlap regions. The deformation mechanisms of the gap and overlap regions also change. The presence of CNTs in non-mineralized collagen reduces the deformation of the gap region and increases the bio-composite elastic modulus to ranges comparable to mineralized collagen. The collagen/CNT bio-composites are also determined to have a higher specific heat than the studied mineralized collagen bio-composites, making them more likely to be resistant to thermal damage that could occur during implantation or functional use of a collagen collagen/CNT bio-composite biomaterial.
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Affiliation(s)
- Marco Fielder
- Multiscale Materials Modeling Lab, Department of Mechanical Engineering, University of Arkansas , Fayetteville, AR, USA
| | - Arun K Nair
- Multiscale Materials Modeling Lab, Department of Mechanical Engineering, University of Arkansas , Fayetteville, AR, USA.,Institute for Nanoscience and Engineering, University of Arkansas , Fayetteville, AR, USA
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Municoy S, Antezana PE, Pérez CJ, Bellino MG, Desimone MF. Tuning the antimicrobial activity of collagen biomaterials through a liposomal approach. J Appl Polym Sci 2021. [DOI: 10.1002/app.50330] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Sofia Municoy
- Instituto de Química y Metabolismo del Fármaco (IQUIMEFA) Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Facultad de Farmacia y Bioquímica Buenos Aires Argentina
| | - Pablo E. Antezana
- Instituto de Química y Metabolismo del Fármaco (IQUIMEFA) Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Facultad de Farmacia y Bioquímica Buenos Aires Argentina
| | - Claudio J. Pérez
- Ciencia e Ingeniería de Polímeros, Instituto de Investigaciones en Ciencia y Tecnología de Materiales (INTEMA) Universidad Nacional de Mar del Plata (UNMdP) Mar del Plata Argentina
| | - Martin G. Bellino
- Instituto de Nanociencia y Nanotecnología Comisión Nacional de Energía Atómica, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) San Martín Argentina
| | - Martín F. Desimone
- Instituto de Química y Metabolismo del Fármaco (IQUIMEFA) Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Facultad de Farmacia y Bioquímica Buenos Aires Argentina
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31
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Adouni M, Mbarki R, Al Khatib F, Eilaghi A. Multiscale modeling of knee ligament biomechanics. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2021; 37:e3413. [PMID: 33174350 DOI: 10.1002/cnm.3413] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2020] [Revised: 10/02/2020] [Accepted: 11/01/2020] [Indexed: 06/11/2023]
Abstract
Knee connective tissues are mainly responsible for joint stability and play a crucial role in restraining excessive motion during regular activities. The damage mechanism of these tissues is directly linked to the microscale collagen level. However, this mechanical connection is still unclear. During this investigation, a multiscale fibril-reinforced hyper-elastoplastic model was developed and statistically calibrated. The model is accounting for the structural architecture of the soft tissue, starting from the tropocollagen molecule that forms fibrils to the whole soft tissue. Model predictions are in agreement with the results of experimental and numerical studies. Further, damage initiation and propagation in the collagen fiber were computed at knee ligaments and located mainly in the superficial layers. Results indicated higher crosslink density required higher tensile stress to elicit fibril damage. This approach is aligned with a realistic simulation of a damaging process and repair attempt. To the best of our knowledge, this is the first model published in which the connective tissue stiffness is simultaneously predicted by encompassing the mesoscopic scales between the molecular and macroscopic levels.
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Affiliation(s)
- Malek Adouni
- Physical Medicine and Rehabilitation Department, Northwestern University, Chicago, Illinois, USA
- Mechanical Engineering Department, Australian College of Kuwait, Kuwait city, Kuwait
| | - Raouf Mbarki
- Mechanical Engineering Department, Australian College of Kuwait, Kuwait city, Kuwait
| | - Fadi Al Khatib
- Mechanical Engineering Department, Australian College of Kuwait, Kuwait city, Kuwait
| | - Armin Eilaghi
- Mechanical Engineering Department, Australian College of Kuwait, Kuwait city, Kuwait
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32
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Investigation of nanoscale failure behaviour of cortical bone under stress by AFM. J Mech Behav Biomed Mater 2020; 112:103989. [DOI: 10.1016/j.jmbbm.2020.103989] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 02/22/2020] [Accepted: 07/13/2020] [Indexed: 01/15/2023]
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33
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An efficient two-scale 3D FE model of the bone fibril array: comparison of anisotropic elastic properties with analytical methods and micro-sample testing. Biomech Model Mechanobiol 2020; 19:2127-2147. [DOI: 10.1007/s10237-020-01328-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2019] [Accepted: 04/11/2020] [Indexed: 12/14/2022]
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34
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Terzi A, Gallo N, Bettini S, Sibillano T, Altamura D, Madaghiele M, De Caro L, Valli L, Salvatore L, Sannino A, Giannini C. Sub‐ and Supramolecular X‐Ray Characterization of Engineered Tissues from Equine Tendon, Bovine Dermis, and Fish Skin Type‐I Collagen. Macromol Biosci 2020; 20:e2000017. [DOI: 10.1002/mabi.202000017] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Accepted: 01/23/2020] [Indexed: 12/20/2022]
Affiliation(s)
- Alberta Terzi
- Institute of Crystallography (IC)National Research Council Bari 70126 Italy
| | - Nunzia Gallo
- Department of Engineering for InnovationUniversity of Salento Lecce 73100 Italy
| | - Simona Bettini
- Department of Engineering for InnovationUniversity of Salento Lecce 73100 Italy
| | - Teresa Sibillano
- Institute of Crystallography (IC)National Research Council Bari 70126 Italy
| | - Davide Altamura
- Institute of Crystallography (IC)National Research Council Bari 70126 Italy
| | - Marta Madaghiele
- Department of Engineering for InnovationUniversity of Salento Lecce 73100 Italy
| | - Liberato De Caro
- Institute of Crystallography (IC)National Research Council Bari 70126 Italy
| | - Ludovico Valli
- Department of Biological and Environmental Sciences and TechnologiesUniversity of Salento Lecce 73100 Italy
| | - Luca Salvatore
- Department of Engineering for InnovationUniversity of Salento Lecce 73100 Italy
| | - Alessandro Sannino
- Department of Engineering for InnovationUniversity of Salento Lecce 73100 Italy
| | - Cinzia Giannini
- Institute of Crystallography (IC)National Research Council Bari 70126 Italy
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35
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Stretching Single Collagen Fibrils Reveals Nonlinear Mechanical Behavior. Biophys J 2020; 118:1401-1408. [PMID: 32070478 DOI: 10.1016/j.bpj.2020.01.038] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Revised: 01/16/2020] [Accepted: 01/23/2020] [Indexed: 12/12/2022] Open
Abstract
The mechanical properties of collagen fibrils play an important role in cell-matrix interactions and are a manifestation of their molecular structure. Using a, to our knowledge, novel combination of uniaxial, longitudinal straining and radial nanoindentation, we found that type I collagen fibrils show a pronounced nonlinear behavior in the form of strain stiffening at strains from 0 to 15%, followed by strain softening at strains from 15 to 25%. At the molecular scale, this surprising phenomenon can be explained by the combination of unfolding of disordered domains and breaking of native cross-links at different stages of strain. Fibrils cross-linked artificially by glutaraldehyde do not show such a behavior, and nanoindentation allowed us to measure the mechanics of the overlap and gap regions in the D-banding individually. The results could have consequences for our understanding of matrix mechanics and the influence of excessive glycation, which has been linked with age-related diseases such as diabetes. Furthermore, the simplicity of the straining method could be attractive in other areas of biophysics at the nanometer scale because it does not require any bespoke instrumentation and is easy to use.
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36
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Ferruzzi J, Zhang Y, Roblyer D, Zaman MH. Multi-scale Mechanics of Collagen Networks: Biomechanical Basis of Matrix Remodeling in Cancer. MULTI-SCALE EXTRACELLULAR MATRIX MECHANICS AND MECHANOBIOLOGY 2020. [DOI: 10.1007/978-3-030-20182-1_11] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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37
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Computational investigation of the effect of water on the nanomechanical behavior of bone. J Mech Behav Biomed Mater 2020; 101:103454. [DOI: 10.1016/j.jmbbm.2019.103454] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2019] [Revised: 08/29/2019] [Accepted: 09/25/2019] [Indexed: 01/22/2023]
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38
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Deogekar S, Islam M, Picu R. Parameters controlling the strength of stochastic fibrous materials. INTERNATIONAL JOURNAL OF SOLIDS AND STRUCTURES 2019; 168:194-202. [PMID: 31395989 PMCID: PMC6687067 DOI: 10.1016/j.ijsolstr.2019.03.033] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Many materials of everyday use are fibrous and their strength is important in most applications. In this work we study the dependence of the strength of random fiber networks on structural parameters such as the network density, cross-link density, fiber tortuosity, and the strength of the inter-fiber cross-links. Athermal networks of cellular and fibrous type are considered. We conclude that the network strength scales linearly with the cross-link number density and with the cross-link strength for a broad range of network parameters, and for both types of networks considered. Network strength is independent of fiber material properties and of fiber tortuosity. This information can be used to design fiber networks for specified strength and, generally, to understand the mechanical behavior of fibrous materials.
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Affiliation(s)
| | | | - R.C. Picu
- Corresponding author, , Tel: 1 518 276 2195
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39
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Seyedkavoosi S, Sevostianov I. Multiscale micromechanical modeling of the elastic properties of dentin. J Mech Behav Biomed Mater 2019; 100:103397. [PMID: 31442944 DOI: 10.1016/j.jmbbm.2019.103397] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2019] [Revised: 05/20/2019] [Accepted: 08/12/2019] [Indexed: 11/28/2022]
Abstract
The paper focuses on multiscale modeling of the elastic properties of dentin. It is modeled as a hierarchical structure consisting of collagen fibers and hydroxyapatite particles at the lower level. Different concentrations of hydroxyapatite in this tissue correspond to peritubular and intertubular dentins. Then, the overall material is modeled as intertubular dentin matrix containing parallel cylindrical holes (the tubules) surrounded by layers of peritubular dentin. At each microstructural level, the model accounts for anisotropy of the constituents. The model predictions are compared with experimental data available in literature.
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Affiliation(s)
- Seyedali Seyedkavoosi
- Department of Mechanical and Aerospace Engineering, New Mexico State University. Las Cruces, NM, 88003, USA
| | - Igor Sevostianov
- Department of Mechanical and Aerospace Engineering, New Mexico State University. Las Cruces, NM, 88003, USA.
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40
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Failure damage mechanical properties of thoracic and abdominal porcine aorta layers and related constitutive modeling: phenomenological and microstructural approach. Biomech Model Mechanobiol 2019; 18:1709-1730. [DOI: 10.1007/s10237-019-01170-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Accepted: 05/12/2019] [Indexed: 12/17/2022]
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41
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Awasthi A, Sharma R, Ghosh R. Monte Carlo type Simulations of Mineralized Collagen Fibril based on Two Scale Asymptotic Homogenization. J Biomech Eng 2019; 141:2720657. [PMID: 30615067 DOI: 10.1115/1.4042439] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Indexed: 11/08/2022]
Abstract
A multi-scale model for mineralized collagen fibril is proposed by taking into account the uncertainties associated with the geometrical properties of mineral phase and its distribution in the organic matrix. The asymptotic homogenization approach along with periodic boundary conditions has been used to derive the effective elastic moduli at two hierarchical length scales, namely: microfibril and mineralized collagen fibril. The uncertainties associated with the mineral plates have been directly included in the finite element mesh by randomly varying their sizes. A total 100 realizations for mineralized collagen fibril model with random distribution have been generated using an in-house MATLAB® code and Monte-Carlo type simulations have been performed under tension load to obtain the statistical equivalent modulus. The deformation response has been studied in both small (= 10%) and large (= 10%) strain regimes. The stress transformation mechanism has also been explored in microfibril which showed stress relaxation in the organic phase upon different stages of mineralization. The elastic moduli for microfibril under small and large strain have been obtained as 1.88 and 6.102 GPa, respectively, and have been used as input for upper scale homogenization procedure. Finally, the characteristic longitudinal moduli of the mineralized collagen fibril in the small and large strain regimes are obtained as 4.08 ± 0.062 and 12.93 ± 0.148 GPa, respectively. All the results are in good agreement to those obtained from previous experiments and molecular dynamics simulations in the literature with a significant reduction in the computational cost.
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Affiliation(s)
- Abhilash Awasthi
- MS Scholar, School of Engineering, Indian Institute of Technology Mandi, Kamand - 175005, Mandi, Himachal Pradesh, India
| | - Rajneesh Sharma
- Assistant Professor, School of Engineering, Indian Institute of Technology Mandi, Kamand - 175005, Mandi, Himachal Pradesh, India
| | - Rajesh Ghosh
- Assistant Professor, School of Engineering, Indian Institute of Technology Mandi, Kamand - 175005, Mandi, Himachal Pradesh, India
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42
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Faisal TR, Adouni M, Dhaher YY. The effect of fibrillar degradation on the mechanics of articular cartilage: a computational model. Biomech Model Mechanobiol 2019; 18:733-751. [DOI: 10.1007/s10237-018-01112-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Accepted: 12/20/2018] [Indexed: 12/21/2022]
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43
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Poma AB, Guzman HV, Li MS, Theodorakis PE. Mechanical and thermodynamic properties of Aβ 42, Aβ 40, and α-synuclein fibrils: a coarse-grained method to complement experimental studies. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2019; 10:500-513. [PMID: 30873322 PMCID: PMC6404408 DOI: 10.3762/bjnano.10.51] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Accepted: 02/08/2019] [Indexed: 05/07/2023]
Abstract
We perform molecular dynamics simulation on several relevant biological fibrils associated with neurodegenerative diseases such as Aβ40, Aβ42, and α-synuclein systems to obtain a molecular understanding and interpretation of nanomechanical characterization experiments. The computational method is versatile and addresses a new subarea within the mechanical characterization of heterogeneous soft materials. We investigate both the elastic and thermodynamic properties of the biological fibrils in order to substantiate experimental nanomechanical characterization techniques that are quickly developing and reaching dynamic imaging with video rate capabilities. The computational method qualitatively reproduces results of experiments with biological fibrils, validating its use in extrapolation to macroscopic material properties. Our computational techniques can be used for the co-design of new experiments aiming to unveil nanomechanical properties of biological fibrils from a point of view of molecular understanding. Our approach allows a comparison of diverse elastic properties based on different deformations , i.e., tensile (Y L), shear (S), and indentation (Y T) deformation. From our analysis, we find a significant elastic anisotropy between axial and transverse directions (i.e., Y T > Y L) for all systems. Interestingly, our results indicate a higher mechanostability of Aβ42 fibrils compared to Aβ40, suggesting a significant correlation between mechanical stability and aggregation propensity (rate) in amyloid systems. That is, the higher the mechanical stability the faster the fibril formation. Finally, we find that α-synuclein fibrils are thermally less stable than β-amyloid fibrils. We anticipate that our molecular-level analysis of the mechanical response under different deformation conditions for the range of fibrils considered here will provide significant insights for the experimental observations.
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Affiliation(s)
- Adolfo B Poma
- Institute of Fundamental Technological Research, Polish Academy of Sciences, Pawińskiego 5B, 02-106 Warsaw, Poland
| | - Horacio V Guzman
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Mai Suan Li
- Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw, Poland
- Institute for Computational Science and Technology, Quang Trung Software City, Tan Chanh Hiep Ward, District 12, Ho Chi Minh City, Vietnam
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44
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Chan VWL, Tobin WR, Zhang S, Winkelstein BA, Barocas VH, Shephard MS, Picu CR. Image-based multi-scale mechanical analysis of strain amplification in neurons embedded in collagen gel. Comput Methods Biomech Biomed Engin 2018; 22:113-129. [PMID: 30450957 DOI: 10.1080/10255842.2018.1538414] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
A general multi-scale strategy is presented for modeling the mechanical environment of a group of neurons that were embedded within a collagenous matrix. The results of the multi-scale simulation are used to estimate the local strains that arise in neurons when the extracellular matrix is deformed. The distribution of local strains was found to depend strongly on the configuration of the embedded neurons relative to the loading direction, reflecting the anisotropic mechanical behavior of the neurons. More importantly, the applied strain on the surrounding extracellular matrix is amplified in the neurons for all loading configurations that are considered. In the most severe case, the applied strain is amplified by at least a factor of 2 in 10% of the neurons' volume. The approach presented in this paper provides an extension to the capability of past methods by enabling the realistic representation of complex cell geometry into a multi-scale framework. The simulation results for the embedded neurons provide local strain information that is not accessible by current experimental techniques.
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Affiliation(s)
- Victor W L Chan
- a Scientific Computational Research Center , Rensselaer Polytechnic Institute, Low Center for Industrial Innocation , Troy , NY , USA
| | - William R Tobin
- a Scientific Computational Research Center , Rensselaer Polytechnic Institute, Low Center for Industrial Innocation , Troy , NY , USA
| | - Sijia Zhang
- b Department of Bioengineering , University of Pennsylvania , Philadelphia , PA , USA
| | - Beth A Winkelstein
- b Department of Bioengineering , University of Pennsylvania , Philadelphia , PA , USA
| | - Victor H Barocas
- c Department of Biomedical Engineering , University of Minnesota , Minneapolis , MN , USA
| | - Mark S Shephard
- a Scientific Computational Research Center , Rensselaer Polytechnic Institute, Low Center for Industrial Innocation , Troy , NY , USA
| | - Catalin R Picu
- a Scientific Computational Research Center , Rensselaer Polytechnic Institute, Low Center for Industrial Innocation , Troy , NY , USA.,d Department of Mechanical , Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute , Troy , NY , USA
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45
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Liu J, Das D, Yang F, Schwartz AG, Genin GM, Thomopoulos S, Chasiotis I. Energy dissipation in mammalian collagen fibrils: Cyclic strain-induced damping, toughening, and strengthening. Acta Biomater 2018; 80:217-227. [PMID: 30240954 PMCID: PMC6510236 DOI: 10.1016/j.actbio.2018.09.027] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2018] [Revised: 08/29/2018] [Accepted: 09/17/2018] [Indexed: 02/04/2023]
Abstract
As the fundamental structural protein in mammals, collagen transmits cyclic forces that are necessary for the mechanical function of tissues, such as bone and tendon. Although the tissue-level mechanical behavior of collagenous tissues is well understood, the response of collagen at the nanometer length scales to cyclical loading remains elusive. To address this major gap, we cyclically stretched individual reconstituted collagen fibrils, with average diameter of 145 ± 42 nm, to small and large strains in the partially hydrated conditions of 60% relative humidity. It is shown that cyclical loading results in large steady-state hysteresis that is reached immediately after the first loading cycle, followed thereafter by limited accumulation of inelastic strain and constant initial elastic modulus. Cyclic loading above 20% strain resulted in 70% increase in tensile strength, from 638 ± 98 MPa to 1091 ± 110 MPa, and 70% increase in toughness, while maintaining the ultimate tensile strain of collagen fibrils not subjected to cyclic loading. Throughout cyclic stretching, the fibrils maintained a steady-state hysteresis, yielding loss coefficients that are 5-10 times larger than those of known homogeneous materials in their modulus range, thus establishing damping of nanoscale collagen fibrils as a major component of damping in tissues. STATEMENT OF SIGNIFICANCE: It is shown that steady-state energy dissipation occurs in individual collagen fibrils that are the building blocks of hard and soft tissues. To date, it has been assumed that energy dissipation in tissues takes place mainly at the higher length scales of the tissue hierarchy due to interactions between collagen fibrils and fibers, and in limited extent inside collagen fibrils. It is shown that individual collagen fibrils need only a single loading cycle to assume a highly dissipative, steady-state, cyclic mechanical response. Mechanical cycling at large strains leads to 70% increase in mechanical strength and values exceeding those of engineering steels. The same cyclic loading conditions also lead to 70% increase in toughness and loss properties that are 5-10 times higher than those of engineering materials with comparable stiffness.
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Affiliation(s)
- Julia Liu
- Aerospace Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Debashish Das
- Aerospace Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Fan Yang
- Aerospace Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Andrea G Schwartz
- Orthopaedic Surgery, Washington University, St. Louis, MO 60613, USA
| | - Guy M Genin
- Mechanical Engineering and Materials Science, Washington University, St. Louis, MO 63130, USA; NSF Science and Technology Center for Engineering Mechanobiology, St. Louis, MO 63130, USA
| | - Stavros Thomopoulos
- Orthopedic Surgery, Biomedical Engineering, Columbia University, New York, NY 10032, USA
| | - Ioannis Chasiotis
- Aerospace Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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Worm-like chain model extensions for highly stretched tropocollagen molecules. J Biomech 2018; 80:129-135. [DOI: 10.1016/j.jbiomech.2018.08.034] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Revised: 08/27/2018] [Accepted: 08/29/2018] [Indexed: 11/18/2022]
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Pantano MF, Speranza G, Galiotis C, Pugno N. A mechanical system for tensile testing of supported films at the nanoscale. NANOTECHNOLOGY 2018; 29:395707. [PMID: 29947330 DOI: 10.1088/1361-6528/aacf50] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Standard tensile tests of materials are usually performed on freestanding specimens. However, such requirement is difficult to implement when the materials of interest are of nanoscopic dimensions due to problems related to their handling and manipulation. In the present paper, a new device is presented for tensile testing of thin nanomaterials, which allows tests to be carried out on specimens initially deposited onto a macroscopic pre-notched substrate. On loading, however, no substrate effects are introduced, allowing the films to be freely stretched. The results obtained from a variety of thin metal or polymeric films are very promising for the further development of this technique as a standard method for nanomaterial mechanical testing.
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Affiliation(s)
- Maria F Pantano
- Laboratory of Bio-inspired & Graphene Nanomechanics, Department of Civil, Environmental and Mechanical Engineering, University of Trento, Via Mesiano 77, I-38123 Trento, Italy
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KRAIEM TESNIM, BARKAOUI ABDELWAHED, MERZOUKI TAREK, CHAFRA MOEZ. CROSS-LINKS MULTISCALE EFFECTS ON BONE ULTRASTRUCTURE BIOMECHANICAL BEHAVIOR. J MECH MED BIOL 2018. [DOI: 10.1142/s0219519418500628] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Bone is a multiscale combination of collagen molecules merged with mineral crystals. Its high rigidity and stability stem amply from its polymeric organic matrix and secondly from the connections established between interdifferent and intradifferent scale components through cross-links. Several studies have shown that the cross-links inhibition results in a reduction in strength of bone but they do not quantify the degree to which these connections contribute to the bone rigidity and toughness. This report is classified among the few works that measure the cross-links multiscale impact on the ultrastructure bone mechanical behavior. This work aims firstly to study the effect of cross-links at the molecule scale and secondly to gather from literature studies results handling with cross-links effects on the other bone ultrastructure scales in order to reveal the multiscale effect of cross-links. This study proves that cross-links increasing number improves the mechanical performance of each scale of bone ultrastructure. On the other hand, cross-links have a multiscale contribution that depends on its rank related to existing cross-links connecting the same geometries and it depends on mechanical characteristics of geometries connected.
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Affiliation(s)
- TESNIM KRAIEM
- LR-11-ES19 Laboratoire de Mécanique Appliquée et Ingénierie (LR-MAI), Ecole Nationale d’Ingénieurs de Tunis, Université de Tunis El Manar 1002, Tunis, Tunisia
| | - ABDELWAHED BARKAOUI
- Laboratoire des Energies Renouvelables et Matériaux Avancés (LERMA), Ecole Supérieure de l’Ingénierie de l’Energie, Université Internationale de Rabat, Rocade RabatSalé, 11100, Rabat-Sala El Jadida, Morocco
| | - TAREK MERZOUKI
- Laboratoire d’Ingénierie des Systèmes de Versailles LISV, Université of Versailles Saint-Quentin 10-12 avenue, de l’Europe, 78140 Vélisy, France
| | - MOEZ CHAFRA
- Laboratoire de Systèmes et de Mécanique Appliquée (LASMAP), Ecole Polytechnique de Tunis, Université de Carthage, 2078, La Marsa, Tunisia
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Phooplub K, Meesane J, Muensit N. Development of Young’s modulus for collagen thin films reinforced with ZnO nanorods probed by Atomic force microscopy. Biomed Phys Eng Express 2018. [DOI: 10.1088/2057-1976/aada23] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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50
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Fielder M, Nair AK. Effects of hydration and mineralization on the deformation mechanisms of collagen fibrils in bone at the nanoscale. Biomech Model Mechanobiol 2018; 18:57-68. [PMID: 30088113 DOI: 10.1007/s10237-018-1067-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Accepted: 07/30/2018] [Indexed: 12/25/2022]
Abstract
Bone is a biomaterial with a structural load-bearing function. Investigating the biomechanics of bone at the nanoscale is important in application to tissue engineering, the development of bioinspired materials, and for characterizing factors such as age, trauma, or disease. At the nanoscale, bone is composed of fibrils that are primarily a composite of collagen, apatite crystals (mineral), and water. Though several studies have been done characterizing the mechanics of fibrils, the effects of variation and distribution of water and mineral content in fibril gap and overlap regions are unexplored. We investigate how the deformation mechanisms of collagen fibrils change as a function of mineral and water content. We use molecular dynamics to study the mechanics of collagen fibrils of 0 wt%, 20 wt%, and 40 wt% mineralization and 0 wt%, 2 wt%, and 4 wt% hydration under applied tensile stresses. We observe that the stress-strain behavior becomes more nonlinear with an increase in hydration, and an increase in mineral content for hydrated fibrils under tensile stress reduces the nonlinear stress versus strain behavior caused by hydration. The Young's modulus of both non-mineralized and mineralized fibrils decreases as the water content increases. As the water content increases, the gap/overlap ratio increases by approximately 40% for the non-mineralized cases and 16% for the highly mineralized cases. Our results indicate that variations in mineral and water content change the distribution of water in collagen fibrils and that the water distribution changes the deformation of gap and overlap regions under tensile loading.
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Affiliation(s)
- Marco Fielder
- Multiscale Materials Modeling Lab, Department of Mechanical Engineering, University of Arkansas, Fayetteville, AR, USA
| | - Arun K Nair
- Multiscale Materials Modeling Lab, Department of Mechanical Engineering, University of Arkansas, Fayetteville, AR, USA. .,Institute for Nanoscience and Engineering, University of Arkansas, 731 W. Dickson Street, Fayetteville, AR, USA.
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