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Harvey M, Cisek R, Alizadeh M, Barzda V, Kreplak L, Tokarz D. High numerical aperture imaging allows chirality measurement in individual collagen fibrils using polarization second harmonic generation microscopy. Nanophotonics 2023; 12:2061-2071. [PMID: 37215945 PMCID: PMC10193268 DOI: 10.1515/nanoph-2023-0177] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Accepted: 03/31/2023] [Indexed: 05/24/2023]
Abstract
Second harmonic generation (SHG) microscopy is a commonly used technique to study the organization of collagen within tissues. However, individual collagen fibrils, which have diameters much smaller than the resolution of most optical systems, have not been extensively investigated. Here we probe the structure of individual collagen fibrils using polarization-resolved SHG (PSHG) microscopy and atomic force microscopy. We find that longitudinally polarized light occurring at the edge of a focal volume of a high numerical aperture microscope objective illuminated with linearly polarized light creates a measurable variation in PSHG signal along the axis orthogonal to an individual collagen fibril. By comparing numerical simulations to experimental data, we are able to estimate parameters related to the structure and chirality of the collagen fibril without tilting the sample out of the image plane, or cutting tissue at different angles, enabling chirality measurements on individual nanostructures to be performed in standard PSHG microscopes. The results presented here are expected to lead to a better understanding of PSHG results from both collagen fibrils and collagenous tissues. Further, the technique presented can be applied to other chiral nanoscale structures such as microtubules, nanowires, and nanoribbons.
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Affiliation(s)
- MacAulay Harvey
- Department of Chemistry, Saint Mary’s University, 923 Robie Street, Halifax, NS, B3H 3C3Canada
| | - Richard Cisek
- Department of Chemistry, Saint Mary’s University, 923 Robie Street, Halifax, NS, B3H 3C3Canada
| | - Mehdi Alizadeh
- Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, ON, L5L 1C6, Canada
- Department of Physics, University of Toronto, 60 St. George St, Toronto, ON, M5S 1A7, Canada
- Laser Research Center, Faculty of Physics, Vilnius University, Sauletekio Av. 9, LT-10222Vilnius, Lithuania
| | - Virginijus Barzda
- Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, ON, L5L 1C6, Canada
- Department of Physics, University of Toronto, 60 St. George St, Toronto, ON, M5S 1A7, Canada
- Laser Research Center, Faculty of Physics, Vilnius University, Sauletekio Av. 9, LT-10222Vilnius, Lithuania
| | - Laurent Kreplak
- Department of Physics and Atmospheric Science and School of Biomedical Engineering, Dalhousie University, Halifax, NS, B3H 4J5, Canada
| | - Danielle Tokarz
- Department of Chemistry, Saint Mary’s University, 923 Robie Street, Halifax, NS, B3H 3C3Canada
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Ryou H, Tay FR, Ossa A, Arola D. Preparation of collagen fibrils from mineralized tissues and evaluation by atomic force microscopy. J Mech Behav Biomed Mater 2023; 138:105624. [PMID: 36543081 PMCID: PMC9845140 DOI: 10.1016/j.jmbbm.2022.105624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 12/01/2022] [Accepted: 12/11/2022] [Indexed: 12/23/2022]
Abstract
Mineralized tissues like bone and dentin are materials that support the distribution of mechanical loads through the body of humans and other animals. While their organic content plays a critical role on the structural behavior of these materials, investigations that quantify the structural properties of collagen fibrils in mineralized tissues at the nanoscale are rather limited. We report a new experimental methodology to prepare samples of dentinal collagen fibrils for evaluation by atomic force microscopy and characterize their mechanical behavior. Specifically, a Dynamic Mechanical Analysis (DMA) of the collagen fibrils was performed to study their viscoelastic behavior. The capacity for viscous dampening in the fibrils was characterized in terms of measures of the energy dissipation, phase angle and loss modulus in both the peak and trough regions of the fibrils. According to the phase angle and the loss modulus, the peak regions of the fibrils exhibit significantly greater stiffness and capacity for dampening than the trough regions. This new approach will help in exploring the role of collagen fibrils in the mechanical behavior of dentin and other mineralized tissues as well as help to understand the potential effects from changes in fibril confirmation with tissue treatments, aging or that result from chronic disease.
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Affiliation(s)
- Heonjune Ryou
- U.S. Naval Research Laboratory, Washington, DC, 20375, USA
| | - Franklin R Tay
- The Dental College of Georgia, Augusta University, Augusta, GA, USA
| | - Alex Ossa
- School of Applied Sciences and Engineering, Universidad Eafit, Medellin, Colombia
| | - Dwayne Arola
- Department of Materials Science and Engineering, University of Washington, Seattle, WA, USA; Department of Restorative Dentistry, University of Washington, Seattle, WA, USA; Department of Oral Health Sciences, University of Washington, Seattle, WA, USA.
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Nalbach M, Chalupa-Gantner F, Spoerl F, de Bar V, Baumgartner B, Andriotis OG, Ito S, Ovsianikov A, Schitter G, Thurner PJ. Instrument for tensile testing of individual collagen fibrils with facile sample coupling and uncoupling. Rev Sci Instrum 2022; 93:054103. [PMID: 35649813 DOI: 10.1063/5.0072123] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Accepted: 04/12/2022] [Indexed: 06/15/2023]
Abstract
Collagen is the major structural protein in human bodies constituting about 30% of the entire protein mass. Through a self-assembly process, triple helical collagen molecules assemble into high aspect-ratio fibers of tens to hundreds of nanometer diameter, known as collagen fibrils (CFs). In the last decade, several methods for tensile testing these CFs emerged. However, these methods are either overly time-consuming or offer low data acquisition bandwidth, rendering dynamic investigation of tensile properties impossible. Here, we describe a novel instrument for tensile testing of individual CFs. CFs are furnished with magnetic beads using a custom magnetic tweezer. Subsequently, CFs are lifted by magnetic force, allowing them to be picked-up by a microgripper structure, which is mounted on a cantilever-based interferometric force probe. A piezo-lever actuator is used to apply tensile displacements and to perform tensile tests of tethered CFs, after alignment. Once the mechanical tests are finished, CFs are removed from the microgripper by application of a magnetic field. Our novel instrument enables tensile tests with at least 25-fold increased throughput compared to tensile testing with an atomic force microscope while achieving force resolution (p-p) of 10 nN at a strain resolution better than 0.1%.
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Affiliation(s)
- Mathis Nalbach
- Institute of Lightweight Design and Structural Biomechanics, TU Wien, Gumpendorfer Straße 7/Objekt 8, 1060 Vienna, Austria
| | | | - Felix Spoerl
- Institute of Lightweight Design and Structural Biomechanics, TU Wien, Gumpendorfer Straße 7/Objekt 8, 1060 Vienna, Austria
| | - Victor de Bar
- Institute of Lightweight Design and Structural Biomechanics, TU Wien, Gumpendorfer Straße 7/Objekt 8, 1060 Vienna, Austria
| | - Benedikt Baumgartner
- Institute of Lightweight Design and Structural Biomechanics, TU Wien, Gumpendorfer Straße 7/Objekt 8, 1060 Vienna, Austria
| | - Orestis G Andriotis
- Institute of Lightweight Design and Structural Biomechanics, TU Wien, Gumpendorfer Straße 7/Objekt 8, 1060 Vienna, Austria
| | - Shingo Ito
- Automation and Control Institute, TU Wien, Gußhausstraße 27-29/E376, 1040 Vienna, Austria
| | - Aleksandr Ovsianikov
- Institute of Materials Science and Technology, TU Wie, Getreidemarkt 9/E308, 1060 Vienna, Austria
| | - Georg Schitter
- Automation and Control Institute, TU Wien, Gußhausstraße 27-29/E376, 1040 Vienna, Austria
| | - Philipp J Thurner
- Institute of Lightweight Design and Structural Biomechanics, TU Wien, Gumpendorfer Straße 7/Objekt 8, 1060 Vienna, Austria
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Bose S, Li S, Mele E, Silberschmidt VV. Exploring the Mechanical Properties and Performance of Type-I Collagen at Various Length Scales: A Progress Report. Materials (Basel) 2022; 15:ma15082753. [PMID: 35454443 PMCID: PMC9025246 DOI: 10.3390/ma15082753] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 04/04/2022] [Accepted: 04/06/2022] [Indexed: 12/30/2022]
Abstract
Collagen is the basic protein of animal tissues and has a complex hierarchical structure. It plays a crucial role in maintaining the mechanical and structural stability of biological tissues. Over the years, it has become a material of interest in the biomedical industries thanks to its excellent biocompatibility and biodegradability and low antigenicity. Despite its significance, the mechanical properties and performance of pure collagen have been never reviewed. In this work, the emphasis is on the mechanics of collagen at different hierarchical levels and its long-term mechanical performance. In addition, the effect of hydration, important for various applications, was considered throughout the study because of its dramatic influence on the mechanics of collagen. Furthermore, the discrepancies in reports of the mechanical properties of collagenous tissues (basically composed of 20-30% collagen fibres) and those of pure collagen are discussed.
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Affiliation(s)
- Shirsha Bose
- Wolfson School of Mechanical, Electrical and Manufacturing Engineering, Loughborough University, Loughborough LE11 3TU, Leicestershire, UK; (S.B.); (S.L.)
| | - Simin Li
- Wolfson School of Mechanical, Electrical and Manufacturing Engineering, Loughborough University, Loughborough LE11 3TU, Leicestershire, UK; (S.B.); (S.L.)
| | - Elisa Mele
- Department of Materials, Loughborough University, Loughborough LE11 3TU, Leicestershire, UK
- Correspondence: (E.M.); (V.V.S.)
| | - Vadim V. Silberschmidt
- Wolfson School of Mechanical, Electrical and Manufacturing Engineering, Loughborough University, Loughborough LE11 3TU, Leicestershire, UK; (S.B.); (S.L.)
- Laboratory of Mechanics of Biocompatible Materials and Devices, Perm National Research Polytechnic University, 614990 Perm, Russia
- Correspondence: (E.M.); (V.V.S.)
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Stylianou A. Assessing Collagen D-Band Periodicity with Atomic Force Microscopy. Materials (Basel) 2022; 15:1608. [PMID: 35208148 DOI: 10.3390/ma15041608] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/23/2022] [Revised: 02/16/2022] [Accepted: 02/17/2022] [Indexed: 02/01/2023]
Abstract
The collagen superfamily includes more than fifty collagen and/or collagen-like proteins with fibril-forming collagen type I being the most abundant protein within the extracellular matrix. Collagen type I plays a crucial role in a variety of functions, it has been associated with many pathological conditions and it is widely used due to its unique properties. One unique nano-scale characteristic of natural occurring collagen type I fibers is the so-called D-band periodicity, which has been associated with collagen natural structure and properties, while it seems to play a crucial role in the interactions between cells and collagen and in various pathological conditions. An accurate characterization of the surface and structure of collagen fibers, including D-band periodicity, on collagen-based tissues and/or (nano-)biomaterials can be achieved by Atomic Force Microscopy (AFM). AFM is a scanning probe microscope and is among the few techniques that can assess D-band periodicity. This review covers issues related to collagen and collagen D-band periodicity and the use of AFM for studying them. Through a systematic search in databases (PubMed and Scopus) relevant articles were identified. The study of these articles demonstrated that AFM can offer novel information concerning D-band periodicity. This study highlights the importance of studying collagen D-band periodicity and proves that AFM is a powerful tool for investigating a number of different properties related to collagen D-band periodicity.
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Peacock C, Lee E, Beral T, Cisek R, Tokarz D, Kreplak L. Buckling and Torsional Instabilities of a Nanoscale Biological Rope Bound to an Elastic Substrate. ACS Nano 2020; 14:12877-12884. [PMID: 32966048 DOI: 10.1021/acsnano.0c03695] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Rope-like structures are ubiquitous in Nature. They are supermolecular assemblies of macromolecules responsible for the structural and mechanical integrity of plant and animal tissues. Collagen fibrils with diameters between 50 and 500 nm and their helical supermolecular structure are good examples of such nanoscale biological ropes. Like man-made laid ropes, fibrils are typically loaded in tension, and due to their large aspect ratio, they are, in principle, prone to buckling and torsional instabilities. One way to study buckling of a rigid rod is to attach it to a stretched elastic substrate that is then returned to its original length. In the case of single collagen fibrils, the observed behavior depends on the degree of hydration. By going from buckling in ambient conditions to immersed in a buffer, fibrils go from the well-known sine wave response to a localized behavior reminiscent of the bird-caging of laid ropes. In addition, in ambient conditions, the sine wave response coexists with the formation of loops along the length of the fibrils, as observed for the torsional instability of a twisted filament when tension is decreased. This work provides direct evidence that single collagen fibrils are highly susceptible to axial compression because of their helical supermolecular structure. As a result, mammals that use collagen fibrils as their main load-bearing element in many tissues have evolved mitigating strategies that protect single fibrils from axial compression damage.
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Affiliation(s)
- Chris Peacock
- Department of Physics and Atmospheric Science, Dalhousie University, Halifax, NS B3H 4J5, Canada
| | - Eva Lee
- Department of Physics and Atmospheric Science, Dalhousie University, Halifax, NS B3H 4J5, Canada
| | - Theo Beral
- Department of Physics and Atmospheric Science, Dalhousie University, Halifax, NS B3H 4J5, Canada
| | - Richard Cisek
- Department of Chemistry, Saint Mary's University, Halifax, NS B3H 3C3, Canada
| | - Danielle Tokarz
- Department of Chemistry, Saint Mary's University, Halifax, NS B3H 3C3, Canada
| | - Laurent Kreplak
- Department of Physics and Atmospheric Science, Dalhousie University, Halifax, NS B3H 4J5, Canada
- School of Biomedical Engineering, Dalhousie University, Halifax, NS B3H 4R2, Canada
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Rus G, Faris IH, Torres J, Callejas A, Melchor J. Why Are Viscosity and Nonlinearity Bound to Make an Impact in Clinical Elastographic Diagnosis? Sensors (Basel) 2020; 20:E2379. [PMID: 32331295 PMCID: PMC7219338 DOI: 10.3390/s20082379] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Revised: 04/17/2020] [Accepted: 04/20/2020] [Indexed: 12/24/2022]
Abstract
The adoption of multiscale approaches by the biomechanical community has caused a major improvement in quality in the mechanical characterization of soft tissues. The recent developments in elastography techniques are enabling in vivo and non-invasive quantification of tissues' mechanical properties. Elastic changes in a tissue are associated with a broad spectrum of pathologies, which stems from the tissue microstructure, histology and biochemistry. This knowledge is combined with research evidence to provide a powerful diagnostic range of highly prevalent pathologies, from birth and labor disorders (prematurity, induction failures, etc.), to solid tumors (e.g., prostate, cervix, breast, melanoma) and liver fibrosis, just to name a few. This review aims to elucidate the potential of viscous and nonlinear elastic parameters as conceivable diagnostic mechanical biomarkers. First, by providing an insight into the classic role of soft tissue microstructure in linear elasticity; secondly, by understanding how viscosity and nonlinearity could enhance the current diagnosis in elastography; and finally, by compounding preliminary investigations of those elastography parameters within different technologies. In conclusion, evidence of the diagnostic capability of elastic parameters beyond linear stiffness is gaining momentum as a result of the technological and imaging developments in the field of biomechanics.
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Affiliation(s)
- Guillermo Rus
- Ultrasonics Group (TEP-959), Department of Structural Mechanics, University of Granada, 18071 Granada, Spain; (G.R.); (I.H.F.); (A.C.)
- Biomechanics Group (TEC-12), Instituto de Investigación Biosanitaria, ibs.GRANADA, 18012 Granada, Spain;
- Excellence Research Unit “ModelingNature” MNat UCE.PP2017.03, University of Granada, 18071 Granada, Spain
| | - Inas H. Faris
- Ultrasonics Group (TEP-959), Department of Structural Mechanics, University of Granada, 18071 Granada, Spain; (G.R.); (I.H.F.); (A.C.)
- Biomechanics Group (TEC-12), Instituto de Investigación Biosanitaria, ibs.GRANADA, 18012 Granada, Spain;
| | - Jorge Torres
- Ultrasonics Group (TEP-959), Department of Structural Mechanics, University of Granada, 18071 Granada, Spain; (G.R.); (I.H.F.); (A.C.)
- Biomechanics Group (TEC-12), Instituto de Investigación Biosanitaria, ibs.GRANADA, 18012 Granada, Spain;
| | - Antonio Callejas
- Ultrasonics Group (TEP-959), Department of Structural Mechanics, University of Granada, 18071 Granada, Spain; (G.R.); (I.H.F.); (A.C.)
- Biomechanics Group (TEC-12), Instituto de Investigación Biosanitaria, ibs.GRANADA, 18012 Granada, Spain;
| | - Juan Melchor
- Biomechanics Group (TEC-12), Instituto de Investigación Biosanitaria, ibs.GRANADA, 18012 Granada, Spain;
- Excellence Research Unit “ModelingNature” MNat UCE.PP2017.03, University of Granada, 18071 Granada, Spain
- Department of Statistics and Operations Research, University of Granada, 18071 Granada, Spain
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Gachon E, Mesquida P. Stretching Single Collagen Fibrils Reveals Nonlinear Mechanical Behavior. Biophys J 2020; 118:1401-8. [PMID: 32070478 DOI: 10.1016/j.bpj.2020.01.038] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [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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