150 results match your criteria fibril gap

Contrasting Local and Macroscopic Effects of Collagen Hydroxylation.

Int J Mol Sci 2021 Aug 23;22(16). Epub 2021 Aug 23.

Department of Chemical and Biological Engineering, Department of Physics, Illinois Institute of Technology, Chicago, IL 60616, USA.

Collagen is heavily hydroxylated. Experiments show that proline hydroxylation is important to triple helix (monomer) stability, fibril assembly, and interaction of fibrils with other molecules. Nevertheless, experiments also show that even without hydroxylation, type I collagen does assemble into its native D-banded fibrillar structure. Read More

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An experimentally informed statistical elasto-plastic mineralised collagen fibre model at the micrometre and nanometre lengthscale.

Sci Rep 2021 Jul 30;11(1):15539. Epub 2021 Jul 30.

School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, UK.

Bone is an intriguingly complex material. It combines high strength, toughness and lightweight via an elaborate hierarchical structure. This structure results from a biologically driven self-assembly and self-organisation, and leads to different deformation mechanisms along the length scales. Read More

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A stochastic micro to macro mechanical model for the evolution of bone-implant interface stiffness.

Acta Biomater 2021 09 12;131:415-423. Epub 2021 Jun 12.

Department of Biomaterials, Sahlgrenska Academy, University of Gothenburg, Göteborg, Sweden.

Upon placement of an implant into living bone, an interface is formed through which various biochemical, biological, physical, and mechanical interactions take place. This interface evolves over time as the mechanical properties of peri-implant bone increase. Owing to the multifactorial nature of interfacial processes, it is challenging to devise a comprehensive model for predicting the mechanical behavior of the bone-implant interface. Read More

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September 2021

The effect of multiple freeze-thaw cycles on the viscoelastic properties and microstructure of bovine superficial digital flexor tendon.

J Mech Behav Biomed Mater 2021 08 21;120:104582. Epub 2021 May 21.

AGH University of Science and Technology, Faculty of Mechanics and Robotics, Krakow, Poland.

The most common injuries of the human musculoskeletal system are related to soft tissue structures such as tendons or ligaments. To repair torn structures, surgical intervention and application of a biological or synthetic graft may be required. A typical procedure for the processing, storage, and distribution of soft tissue grafts involves at least two freezing/thawing (F/T) cycles. Read More

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Role of Water Molecules and Helix Structure Stabilization in the Laser-Induced Disruption of Amyloid Fibrils Observed by Nonequilibrium Molecular Dynamics Simulations.

J Phys Chem B 2021 05 7;125(19):4964-4976. Epub 2021 May 7.

IR Free Electron Laser Research Center, Research Institute for Science and Technology, Organization for Research Advancement, Tokyo University of Science, Noda, Chiba 278-8510, Japan.

Water plays a crucial role in the formation and destruction of biomolecular structures. The mechanism for destroying biomolecular structures was thought to be an active breaking of hydrogen bonds by water molecules. However, using nonequilibrium molecular dynamics simulations, in which an amyloid-β amyloid fibril was destroyed via infrared free-electron laser (IR-FEL) irradiation, we discovered a new mechanism, in which water molecules disrupt protein aggregates. Read More

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Tuning the Structure of Nylon 6,6 Electrospun Bundles to Mimic the Mechanical Performance of Tendon Fascicles.

Front Bioeng Biotechnol 2021 6;9:626433. Epub 2021 Apr 6.

Department of Industrial Engineering, Alma Mater Studiorum-Università di Bologna, Bologna, Italy.

Tendon and ligament injuries are triggered by mechanical loading, but the specific mechanisms are not yet clearly identified. It is well established however, that the inflection and transition points in tendon stress-strain curves represent thresholds that may signal the onset of irreversible fibrillar sliding. This phenomenon often results in a progressive macroscopic failure of these tissues. Read More

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Piezoelectric Heterogeneity in Collagen Type I Fibrils Quantitatively Characterized by Piezoresponse Force Microscopy.

ACS Biomater Sci Eng 2020 12 10;6(12):6680-6689. Epub 2020 Nov 10.

Mechanical and Aerospace Engineering, The Ohio State University, 201 W 19th Avenue, Columbus, Ohio 43210, United States.

Piezoelectricity of Type I collagen can provide the stress-generated potential that is considered to be one of the candidate mechanisms to explain bone's adaptation to loading. However, it is still challenging to quantify piezoelectricity because of its heterogeneity and small magnitude. In this study, resonance-enhanced piezoresponse force microscopy (PFM) was utilized to amplify a weak piezoresponse of a single collagen fibril with a carefully calibrated cantilever. Read More

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December 2020

Direct comparison of five different 3D extracellular matrix model systems for characterization of cancer cell migration.

Cancer Rep (Hoboken) 2020 10 8;3(5):e1257. Epub 2020 Jun 8.

Cell Biology Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland, USA.

Background: Three-dimensional (3D) in vitro model systems can bridge the gap between regular two-dimensional cell culture and whole-animal studies. Analyses of cancer cell migration and invasion increasingly use differing 3D systems, which may produce conflicting findings.

Aims: We directly compared different 3D extracellular matrix systems for studying cancer cell migration/invasion by analyzing cell morphologies and quantifying aspects of cell migration including speed and directional persistence using automated computer-based cell tracking. Read More

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October 2020

Analysis of opticin binding to collagen fibrils identifies a single binding site in the gap region and a high specificity towards thin heterotypic fibrils containing collagens II, and XI or V/XI.

PLoS One 2020 7;15(8):e0234672. Epub 2020 Aug 7.

Division of Evolution and Genomic Sciences, School of Biological Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom.

Opticin is a class III member of the extracellular matrix small leucine-rich repeat protein/proteoglycan (SLRP) family found in vitreous humour and cartilage. It was first identified associated with the surface of vitreous collagen fibrils and several other SLRPs are also known to bind collagen fibrils and it some cases alter fibril morphology. The purpose of this study was to investigate the binding of opticin to the collagen II-containing fibrils found in vitreous and cartilage. Read More

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October 2020

MCF7 Spheroid Development: New Insight about Spatio/Temporal Arrangements of TNTs, Amyloid Fibrils, Cell Connections, and Cellular Bridges.

Int J Mol Sci 2020 Jul 29;21(15). Epub 2020 Jul 29.

Department of Biotechnology and Life Sciences, University of Insubria, via J.H. Dunant 3, 21100 Varese, Italy.

Human breast adenocarcinoma cells (MCF7) grow in three-dimensional culture as spheroids that represent the structural complexity of avascular tumors. Therefore, spheroids offer a powerful tool for studying cancer development, aggressiveness, and drug resistance. Notwithstanding the large amount of data regarding the formation of MCF7 spheroids, a detailed description of the morpho-functional changes during their aggregation and maturation is still lacking. Read More

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Differences in the free energies between the excited states of A40 and A42 monomers encode their aggregation propensities.

Proc Natl Acad Sci U S A 2020 08 30;117(33):19926-19937. Epub 2020 Jul 30.

Department of Chemistry, The University of Texas at Austin, Austin, TX 78712;

The early events in the aggregation of the intrinsically disordered peptide, amyloid-β (Aβ), involve transitions from the disordered free energy ground state to assembly-competent states. Are the fingerprints of order found in the amyloid fibrils encoded in the conformations that the monomers access at equilibrium? If so, could the enhanced aggregation rate of Aβ42 compared to Aβ40 be rationalized from the sparsely populated high free energy states of the monomers? Here, we answer these questions in the affirmative using coarse-grained simulations of the self-organized polymer-intrinsically disordered protein (SOP-IDP) model of Aβ40 and Aβ42. Although both the peptides have practically identical ensemble-averaged properties, characteristic of random coils (RCs), the conformational ensembles of the two monomers exhibit sequence-specific heterogeneity. Read More

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Disordered Filaments Mediate the Fibrillogenesis of Type I Collagen in Solution.

Biomacromolecules 2020 09 10;21(9):3631-3643. Epub 2020 Aug 10.

EaStCHEM, School of Chemistry, The King's Buildings, University of Edinburgh, David Brewster Road, Edinburgh EH9 3FJ, U.K.

Collagen type I is one of the major structural proteins in mammals, providing tissues such as cornea, tendon, bone, skin, and dentin with mechanical stability, strength, and toughness. Collagen fibrils are composed of collagen molecules arranged in a quarter-stagger array that gives rise to a periodicity of 67 nm along the fibril axis, with a 30 nm overlap zone and a 37 nm gap zone. The formation of such highly organized fibrils is a self-assembly process where electrostatic and hydrophobic interactions play a critical role in determining the staggering of the molecules with 67 nm periodicity. Read More

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September 2020

Increased Fibroblast Metabolic Activity of Collagen Scaffolds via the Addition of Propolis Nanoparticles.

Materials (Basel) 2020 Jul 13;13(14). Epub 2020 Jul 13.

National Laboratory of Nanotechnology (LANOTEC), National Center of High Technology (LANOTEC-CeNAT-CONARE), Pavas, 1174-1200 San José, Costa Rica.

Propolis natural extracts have been used since ancient times due to their antioxidant, anti-inflammatory, antiviral, and antimicrobial activities. In this study, we produced scaffolds of type I collagen, extracted from Wistar Hanover rat tail tendons, and impregnated them with propolis nanoparticles (NPs) for applications in regenerative medicine. Our results show that the impregnation of propolis NPs to collagen scaffolds affected the collagen denaturation temperature and tensile strength. Read More

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Orientational order induced by a polymer network in the isotropic phase of liquid crystal.

Phys Rev E 2020 May;101(5-1):052705

California State University, Sacramento, 6000 J Street, Sacramento, California 95608, USA.

We studied the paranematic ordering induced by a polymer network in the isotropic phase of a liquid crystal (LC) that occurs in polymer-stabilized cells with bend configuration of the LC director (π cells) fabricated via photopolymerization of photoreactive monomer RM 82 added in small concentrations (3-5 wt %) to a nematic LC [4-cyano-4'-pentylbiphenyl (5CB)] when low voltage was applied across the cell. The polymer network formed in the nematic phase of the LC consists of fine fibrils that are aligned along the LC director and thus mirror the bend deformation of the LC at the time of polymerization. When heated to temperatures above the nematic-to-isotropic (N-I) phase transition such highly ordered polymer network anchors LC molecules providing ordering of the LC around the fibrils which results in unusually high optical retardation of the cell, R_{cell}. Read More

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Comparative study of the stabilities of synthetic and natural transthyretin amyloid fibrils.

J Biol Chem 2020 08 22;295(33):11379-11387. Epub 2020 Jun 22.

Department of Molecular Medicine, Institute of Biochemistry, University of Pavia, Pavia, Italy

Systemic amyloidosis caused by extracellular deposition of insoluble fibrils derived from the pathological aggregation of circulating proteins, such as transthyretin, is a severe and usually fatal condition. Elucidation of the molecular pathogenic mechanism of the disease and discovery of effective therapies still represents a challenging medical issue. The preparation of amyloid fibrils that exhibit structural and biochemical properties closely similar to those of natural fibrils is central to improving our understanding of the biophysical basis of amyloid formation and may offer an important tool for drug discovery. Read More

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Changes and quantitative characterization of hyper-viscoelastic biomechanical properties for young corneal stroma after standard corneal cross-linking treatment with different ultraviolet-A energies.

Acta Biomater 2020 09 7;113:438-451. Epub 2020 Jun 7.

Tianjin Key Lab of Ophthalmology and Visual Science, Tianjin Eye Hospital, Tianjin 300020 China; Clinical College of Ophthalmology, Tianjin Medical University, Tianjin 300070 China.

Corneal collagen cross-linking (CXL) treatment can restore vision in patients suffering from keratoconus and corneal injury, by improving the mechanical properties of the cornea. The correlation between ultraviolet-A (UVA) irradiant energies of standard CXL (SCXL) and corneal visco-hyperelastic mechanical behavior remains unknown. In this study, SCXL with four different UVA irradiant energy doses (0-5. Read More

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September 2020

Effect of High Molecular Weight PPTA on Liquid Crystalline Phase and Spinning Process of Aramid Fibers.

Polymers (Basel) 2020 May 25;12(5). Epub 2020 May 25.

State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai 201620, China.

High molecular weight poly (-phenylene-terephthalamide) (h-PPTA) was blended with the commercial PPTA in concentrated sulfuric acid to improve the spinnability of the polymer solutions and the mechanical properties of the as-spun fibers. h-PPTA in the solution has an influence on the temperature of the formation of liquid crystalline phenomenon. The temperature range with the existence of the liquid crystalline phase increases upon the contents of h-PPTA in the solution, and the extended temperature window is helpful for the preparation of PPTA fibers by the dry-jet wet-spinning technology. Read More

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Flightless anchors IQGAP1 and R-ras to mediate cell extension formation and matrix remodeling.

Mol Biol Cell 2020 07 20;31(15):1595-1610. Epub 2020 May 20.

Faculty of Dentistry, University of Toronto, Toronto, ON M5G 1G6, Canada.

Tractional remodeling of collagen fibrils by fibroblasts requires long cell extensions that mediate fibril alignment. The formation of these cell extensions involves flightless I (FliI), an actin-binding protein that contains a leucine-rich-repeat (LRR), which binds R-ras and may regulate cdc42. We considered that FliI interacts with small GTPases and their regulators to mediate assembly of cell extensions. Read More

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A search for apatite crystals in the gap zone of collagen fibrils in bone using dark-field illumination.

Bone 2020 06 5;135:115304. Epub 2020 Mar 5.

School of Biomedical Engineering, McMaster University, Hamilton, Ontario, Canada; Department of Materials Science and Engineering, McMaster University, Hamilton, Ontario, Canada.

Bright-field transmission electron microscope (TEM) images of ion milled or focused ion beam (FIB) sections of cortical bone sectioned parallel to the long axis of collagen fibrils display an electron-dense phase in the gap zones of the fibrils, as well as elongated plates (termed mineral lamellae) comprised of apatite crystals, which surround and lie between the fibrils. Energy dispersive X-ray spectroscopy (EDS) and electron energy loss spectroscopy (EELS) studies by others have shown that the material in the gap zones is calcium phosphate. Dark-field (DF) images are capable of revealing the projected position of crystals of apatite in a section of bone. Read More

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Combining molecular dynamics simulations and experimental analyses in protein misfolding.

Adv Protein Chem Struct Biol 2019 6;118:33-110. Epub 2020 Jan 6.

Department of Electrical and Computer Engineering, University of Alberta, Edmonton, Canada.

The fold of a protein determines its function and its misfolding can result in loss-of-function defects. In addition, for certain proteins their misfolding can lead to gain-of-function toxicities resulting in protein misfolding diseases such as Alzheimer's, Parkinson's, or the prion diseases. In all of these diseases one or more proteins misfold and aggregate into disease-specific assemblies, often in the form of fibrillar amyloid deposits. Read More

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Promoting tau secretion and propagation by hyperactive p300/CBP via autophagy-lysosomal pathway in tauopathy.

Mol Neurodegener 2020 01 6;15(1). Epub 2020 Jan 6.

Gladstone Institute of Neurological Disease, University of California, San Francisco, CA, 94158, USA.

Background: The trans-neuronal propagation of tau has been implicated in the progression of tau-mediated neurodegeneration. There is critical knowledge gap in understanding how tau is released and transmitted, and how that is dysregulated in diseases. Previously, we reported that lysine acetyltransferase p300/CBP acetylates tau and regulates its degradation and toxicity. Read More

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January 2020

Cryoballoon vs. radiofrequency lesions as detected by late-enhancement cardiac magnetic resonance after ablation of paroxysmal atrial fibrillation: a case-control study.

Europace 2020 03;22(3):382-387

Arrhythmia Unit, Department of Cardiology, Cardiovascular Clinical Institute, UFA (Unitat de Fibril·lació Auricular de l'Hospital Clínic), Hospital Clínic, Universitat de Barcelona. C/Villarroel N° 170, 08036 Barcelona, Spain.

Aims: Cryoballoon (CB) ablation has emerged as a reliable modality to isolate pulmonary veins (PVs) in atrial fibrillation. Ablation lesions and the long-term effects of energy delivery can be assessed by delayed-enhancement cardiac magnetic resonance (DE-CMR). The aim of the study was to compare the number, extension, and localization of gaps in CB and radiofrequency (RF) techniques in pulmonary vein isolation (PVI). Read More

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Needle-shaped amyloid deposition in rat mammary gland: evidence of a novel amyloid fibril protein.

Amyloid 2020 Mar 15;27(1):25-35. Epub 2019 Oct 15.

Pathology Department, Nonclinical Research Center, Drug Development Service Segment, LSI Medicine Corporation, Uto, Japan.

Amyloidosis is an extremely rare event in rats. In this study, we report that lipopolysaccharide binding protein (LBP) is the most likely amyloidogenic protein in rat mammary amyloidosis. Histologically, corpora amylacea (CA) and stromal amyloid (SA) were observed in rat mammary glands, and needle-shaped amyloid (NA) was also observed on the surface or gap of CA and SA. Read More

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Nanomechanical mapping of single collagen fibrils under tension.

Nanoscale 2019 Aug;11(30):14417-14425

Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia, Canada.

At the most fundamental level, collagen fibrils are rope-like structures assembled from triple-helical collagen molecules. One key structural characteristic of the fibril is the 67 nm D-band pattern arising from the quarter-stagger packing of the molecules. Our current understanding of the structural changes induced by tensile loading of collagen fibrils comes mostly from atomistic molecular dynamics simulations and tissue level experiments. Read More

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Identification of collagen fibrils in cross sections of bone by electron energy loss spectroscopy (EELS).

Micron 2019 09 20;124:102706. Epub 2019 Jun 20.

School of Biomedical Engineering, McMaster University, Hamilton, ON, L8S 4L7, Canada; School of Geography and Earth Sciences, McMaster University, Hamilton, ON, L8S 4K1, Canada. Electronic address:

Transmission electron microscopic (TEM) images of ion-milled bovid cortical bone cut approximately normal to the axes of fibrils show that mineral occurs in the form of plates surrounding and laying between circular or elliptical features about 50 nm in diameter. The classification of these features as either pores or collagen fibrils is highly debated. Electron energy loss spectroscopy (EELS) mapping of these features in ion milled sections shows that they are lacking significant amounts of mineral or collagen, although their appearance suggests that they are cross sections of collagen fibrils. Read More

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September 2019

Elastic, Viscoelastic and Fibril-Reinforced Poroelastic Material Properties of Healthy and Osteoarthritic Human Tibial Cartilage.

Ann Biomed Eng 2019 Apr 28;47(4):953-966. Epub 2019 Jan 28.

Department of Applied Physics, University of Eastern Finland, POB 1627, 70211, Kuopio, Finland.

Articular cartilage constituents (collagen, proteoglycans, fluid) are significantly altered during osteoarthritis (OA). A fibril-reinforced poroelastic (FRPE) material model can separate the contribution of each constituent on the mechanical response of cartilage. Yet, these properties and their OA related alterations are not known for human tibial cartilage. Read More

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Delayed Gadolinium Enhancement Magnetic Resonance Imaging Detected Anatomic Gap Length in Wide Circumferential Pulmonary Vein Ablation Lesions Is Associated With Recurrence of Atrial Fibrillation.

Circ Arrhythm Electrophysiol 2018 12;11(12):e006659

Institut Clínic de Malalties Cardiovasculars, Hospital Clinic, Universitat de Barcelona, Catalonia, Spain (M.L., F.A., R.B., E.M.B., F.C., J.C., G.C., N.E., A.C., E.G., E.Z., J.M.T., S.P.-G., R.J.P., A.D., M.S., J.B., A.B., L.M.).

Background: There is limited knowledge about the impact of anatomic gaps as assessed by delayed gadolinium enhancement cardiac magnetic resonance on atrial fibrillation (AF) recurrence after first pulmonary vein (PV) isolation.

Methods: Consecutive patients underwent delayed gadolinium enhancement cardiac magnetic resonance 3 months after radiofrequency circumferential PV isolation. Delayed gadolinium enhancement cardiac magnetic resonance images were assessed from 360 PV resulting in 2880 segments in the 2×8-segment model from 94 patients (52±11 years, 62% paroxysmal AF). Read More

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December 2018

Parkinson's disease and multiple system atrophy have distinct α-synuclein seed characteristics.

J Biol Chem 2019 01 26;294(3):1045-1058. Epub 2018 Nov 26.

the Center for Alzheimer's and Neurodegenerative Diseases, Peter O'Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, Texas 75390.

Parkinson's disease (PD) and multiple system atrophy (MSA) are distinct clinical syndromes characterized by the pathological accumulation of α-synuclein (α-syn) protein fibrils in neurons and glial cells. These disorders and other neurodegenerative diseases may progress via prion-like mechanisms. The prion model of propagation predicts the existence of "strains" that link pathological aggregate structure and neuropathology. Read More

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January 2019

Creating Elastic Organic Crystals of π-Conjugated Molecules with Bending Mechanofluorochromism and Flexible Optical Waveguide.

Angew Chem Int Ed Engl 2018 Dec 21;57(52):17002-17008. Epub 2018 Nov 21.

Life Science and Applied Chemistry, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya, 466-8555, Japan.

To create low band-gap, fluorescent, and elastic organic crystal emitters, we focused on an extended π-conjugated system based on: a) a planar conformation,b) a rigid structure, and c) controlled intermolecular interactions. Herein, we report on two fluorescent and highly flexible organic crystals (1 and 2) which could bend under an applied stress. The bent crystals rapidly recover their straight shape upon release of the stress. Read More

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December 2018

Effects of hydration and mineralization on the deformation mechanisms of collagen fibrils in bone at the nanoscale.

Biomech Model Mechanobiol 2019 Feb 7;18(1):57-68. Epub 2018 Aug 7.

Multiscale Materials Modeling Lab, Department of Mechanical Engineering, University of Arkansas, Fayetteville, AR, USA.

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. Read More

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February 2019