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Sergi PN. Some Mechanical Constraints to the Biomimicry with Peripheral Nerves. Biomimetics (Basel) 2023; 8:544. [PMID: 37999185 PMCID: PMC10669299 DOI: 10.3390/biomimetics8070544] [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: 08/08/2023] [Revised: 10/01/2023] [Accepted: 10/20/2023] [Indexed: 11/25/2023] Open
Abstract
Novel high technology devices built to restore impaired peripheral nerves should be biomimetic in both their structure and in the biomolecular environment created around regenerating axons. Nevertheless, the structural biomimicry with peripheral nerves should follow some basic constraints due to their complex mechanical behaviour. However, it is not currently clear how these constraints could be defined. As a consequence, in this work, an explicit, deterministic, and physical-based framework was proposed to describe some mechanical constraints needed to mimic the peripheral nerve behaviour in extension. More specifically, a novel framework was proposed to investigate whether the similarity of the stress/strain curve was enough to replicate the natural nerve behaviour. An original series of computational optimizing procedures was then introduced to further investigate the role of the tangent modulus and of the rate of change of the tangent modulus with strain in better defining the structural biomimicry with peripheral nerves.
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Affiliation(s)
- Pier Nicola Sergi
- Translational Neural Engineering Area, The Biorobotics Institute and Department of Excellence in Robotics and AI, Sant'Anna School of Advanced Studies, 56127 Pisa, Italy
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2
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Karpas ED, Kun F. Blending stiffness and strength disorder can stabilize fracture. Phys Rev E 2016; 93:033002. [PMID: 27078436 DOI: 10.1103/physreve.93.033002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Indexed: 11/07/2022]
Abstract
Quasibrittle behavior, where macroscopic failure is preceded by stable damaging and intensive cracking activity, is a desired feature of materials because it makes fracture predictable. Based on a fiber-bundle model with global load sharing we show that blending strength and stiffness disorder of material elements leads to the stabilization of fracture, i.e., samples that are brittle when one source of disorder is present become quasibrittle as a consequence of blending. We derive a condition of quasibrittle behavior in terms of the joint distribution of the two sources of disorder. Breaking bursts have a power-law size distribution of exponent 5/2 without any crossover to a lower exponent when the amount of disorder is gradually decreased. The results have practical relevance for the design of materials to increase the safety of constructions.
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Affiliation(s)
- Ehud D Karpas
- Weizmann Institute of Science, Rehovot, 7610001, Israel
| | - Ferenc Kun
- Department of Theoretical Physics, University of Debrecen, P.O. Box 5, H-4010 Debrecen, Hungary
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Abstract
Tendon exhibits anisotropic, inhomogeneous and viscoelastic mechanical properties that are determined by its complicated hierarchical structure and varying amounts/organization of different tissue constituents. Although extensive research has been conducted to use modelling approaches to interpret tendon structure-function relationships in combination with experimental data, many issues remain unclear (i.e. the role of minor components such as decorin, aggrecan and elastin), and the integration of mechanical analysis across different length scales has not been well applied to explore stress or strain transfer from macro- to microscale. This review outlines mathematical and computational models that have been used to understand tendon mechanics at different scales of the hierarchical organization. Model representations at the molecular, fibril and tissue levels are discussed, including formulations that follow phenomenological and microstructural approaches (which include evaluations of crimp, helical structure and the interaction between collagen fibrils and proteoglycans). Multiscale modelling approaches incorporating tendon features are suggested to be an advantageous methodology to understand further the physiological mechanical response of tendon and corresponding adaptation of properties owing to unique in vivo loading environments.
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Affiliation(s)
- Fei Fang
- Department of Mechanical Engineering and Materials Science , Washington University in St Louis , St Louis, MO 63130 , USA
| | - Spencer P Lake
- Department of Mechanical Engineering and Materials Science, Washington University in St Louis, St Louis, MO 63130, USA; Department of Biomedical Engineering, Washington University in St Louis, St Louis, MO 63130, USA; Department of Orthopaedic Surgery, Washington University in St Louis, St Louis, MO 63130, USA
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Balsamo R, Boak M, Nagle K, Peethambaran B, Layton B. Leaf biomechanical properties in Arabidopsis thaliana polysaccharide mutants affect drought survival. J Biomech 2015; 48:4124-4129. [PMID: 26520913 DOI: 10.1016/j.jbiomech.2015.10.016] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Revised: 04/30/2015] [Accepted: 10/14/2015] [Indexed: 01/01/2023]
Abstract
Individual sugars are the building blocks of cell wall polysaccharides, which in turn comprise a plant׳s overall architectural structure. But which sugars play the most prominent role in maintaining a plant׳s mechanical stability during large cellular deformations induced by drought? We investigated the individual contributions of several genes that are involved in the synthesis of monosaccharides which are important for cell wall structure. We then measured drought tolerance and mechanical integrity during simulated drought in Arabidopsis thaliana. To assess mechanical properties, we designed a small-scale tensile tester for measuring failure strain, ultimate tensile stress, work to failure, toughness, and elastic modulus of 6-week-old leaves in both hydrated and drought-simulated states. Col-0 mutants used in this study include those deficient in lignin, cellulose, components of hemicellulose such as xylose and fucose, the pectic components arabinose and rhamnose, as well as mutants with enhanced arabinose and total pectin content. We found that drought tolerance is correlated to the mechanical and architectural stability of leaves as they experience dehydration. Of the mutants, S096418 with mutations for reduced xylose and galactose was the least drought tolerant, while the arabinose-altered CS8578 mutants were the least affected by water loss. There were also notable correlations between drought tolerance and mechanical properties in the diminished rhamnose mutant, CS8575 and the dehydrogenase-disrupted S120106. Our findings suggest that components of hemicellulose and pectins affect leaf biomechanical properties and may play an important role in the ability of this model system to survive drought.
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Affiliation(s)
- Ronald Balsamo
- Department of Biology, Villanova University, Villanova, PA 19085, United States
| | - Merewyn Boak
- Department of Biology, Villanova University, Villanova, PA 19085, United States
| | - Kayla Nagle
- Department of Chemistry and Biochemistry, The University of Montana, Missoula, MT 59812, United States
| | - Bela Peethambaran
- Department of Biological Sciences, Division of the Biological Sciences, University of the Sciences, Philadelphia, PA 19104, United States
| | - Bradley Layton
- Department of Chemistry and Biochemistry, The University of Montana, Missoula, MT 59812, United States; Department of Applied Computing and Engineering Technology, The University of Montana, Missoula, MT 59812, United States.
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Fessel G, Li Y, Diederich V, Guizar-Sicairos M, Schneider P, Sell DR, Monnier VM, Snedeker JG. Advanced glycation end-products reduce collagen molecular sliding to affect collagen fibril damage mechanisms but not stiffness. PLoS One 2014; 9:e110948. [PMID: 25364829 PMCID: PMC4217736 DOI: 10.1371/journal.pone.0110948] [Citation(s) in RCA: 100] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2014] [Accepted: 08/08/2014] [Indexed: 12/28/2022] Open
Abstract
Advanced glycation end-products (AGE) contribute to age-related connective tissue damage and functional deficit. The documented association between AGE formation on collagens and the correlated progressive stiffening of tissues has widely been presumed causative, despite the lack of mechanistic understanding. The present study investigates precisely how AGEs affect mechanical function of the collagen fibril--the supramolecular functional load-bearing unit within most tissues. We employed synchrotron small-angle X-ray scattering (SAXS) and carefully controlled mechanical testing after introducing AGEs in explants of rat-tail tendon using the metabolite methylglyoxal (MGO). Mass spectrometry and collagen fluorescence verified substantial formation of AGEs by the treatment. Associated mechanical changes of the tissue (increased stiffness and failure strength, decreased stress relaxation) were consistent with reports from the literature. SAXS analysis revealed clear changes in molecular deformation within MGO treated fibrils. Underlying the associated increase in tissue strength, we infer from the data that MGO modified collagen fibrils supported higher loads to failure by maintaining an intact quarter-staggered conformation to nearly twice the level of fibril strain in controls. This apparent increase in fibril failure resistance was characterized by reduced side-by-side sliding of collagen molecules within fibrils, reflecting lateral molecular interconnectivity by AGEs. Surprisingly, no change in maximum fibril modulus (2.5 GPa) accompanied the changes in fibril failure behavior, strongly contradicting the widespread assumption that tissue stiffening in ageing and diabetes is directly related to AGE increased fibril stiffness. We conclude that AGEs can alter physiologically relevant failure behavior of collagen fibrils, but that tissue level changes in stiffness likely occur at higher levels of tissue architecture.
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Affiliation(s)
- Gion Fessel
- Department of Orthopedics, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
| | - Yufei Li
- Department of Orthopedics, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
| | - Vincent Diederich
- Institute for Chemical and Bioengineering, ETH Zurich, Zurich, Switzerland
| | | | - Philipp Schneider
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
- Faculty of Engineering and the Environment, University of Southampton, Southampton, United Kingdom
| | - David R. Sell
- Department of Pathology, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Vincent M. Monnier
- Department of Pathology, Case Western Reserve University, Cleveland, Ohio, United States of America
- Department of Biochemistry, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Jess G. Snedeker
- Department of Orthopedics, Balgrist University Hospital, University of Zurich, Zurich, Switzerland
- Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
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Watson REB, Gibbs NK, Griffiths CEM, Sherratt MJ. Damage to skin extracellular matrix induced by UV exposure. Antioxid Redox Signal 2014; 21:1063-77. [PMID: 24124905 DOI: 10.1089/ars.2013.5653] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
SIGNIFICANCE Chronic exposure to environmental ultraviolet radiation (UVR) plays a key role in both photocarcinogenesis and induction of accelerated skin aging. Although the spatiotemporal consequences of UVR exposure for the composition and architecture of the dermal extracellular matrix (ECM) are well characterized, the pathogenesis of photoaging remains poorly defined. Given the compelling evidence for the role of reactive oxygen species (ROS) as mediators of photoaging, UVR-exposed human skin may be an accessible model system in which to characterize the role of oxidative damage in both internal and external tissues. RECENT ADVANCES Although the cell-mediated degradation of dermal components via UVR-induced expression of ECM proteases has long been identified as an integral part of the photoaging pathway, the relative importance and identity of cellular and extracellular photosensitizers (direct hit and bystanders models, respectively) in initiating this enzymatic activity is unclear. Recently, both age-related protein glycation and relative amino-acid composition have been identified as potential risk factors for photo-ionization and/or photo-sensitization. Here, we propose a selective multi-hit model of photoaging. CRITICAL ISSUES Bioinformatic analyses can be employed to identify candidate UVR targets/photosensitizers, but the action of UVR on protein structure and/or ROS production should be verified experimentally. Crucially, in the case of biochemically active ECM components such as fibronectin and fibrillin, the downstream effects of photo-degradation on tissue homeostasis remain to be confirmed. FUTURE DIRECTIONS Both topical antioxidants and inhibitors of detrimental cell signaling may be effective in abrogating the effects of specific UVR-mediated protein degradation in the dermis.
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Affiliation(s)
- Rachel E B Watson
- 1 The Dermatology Centre, Salford Royal Hospital, Institute of Inflammation and Repair, The University of Manchester , Manchester Academic Health Science Centre, Manchester, United Kingdom
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Rickett TA, Amoozgar Z, Tuchek CA, Park J, Yeo Y, Shi R. Rapidly photo-cross-linkable chitosan hydrogel for peripheral neurosurgeries. Biomacromolecules 2010; 12:57-65. [PMID: 21128673 DOI: 10.1021/bm101004r] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Restoring continuity to severed peripheral nerves is crucial to regeneration and enables functional recovery. However, the two most common agents for coaptation, sutures and fibrin glues, have drawbacks such as inflammation, pathogenesis, and dehiscence. Chitosan-based adhesives are a promising alternative, reported to have good cytocompatibility and favorable immunogenicity. A photo-cross-linkable hydrogel based on chitosan is proposed as a new adhesive for peripheral nerve anastomosis. Two Az-chitosans were synthesized by conjugating 4-azidobenzoic acid with low (LMW, 15 kDa) and high (HMW, 50-190 kDa) molecular weight chitosans. These solutions formed a hydrogel in less than 1 min under UV light. The LMW Az-chitosan was more tightly cross-linked than the HMW variant, undergoing significantly less swelling and possessing a higher rheological storage modulus, and both Az-chitosan gels were stiffer than commercial fibrin glue. Severed nerves repaired by Az-chitosan adhesives tolerated longitudinal forces comparable or superior to fibrin glue. Adhesive exposure to intact nerves and neural cell culture showed both Az-chitosans to be nontoxic in the acute (minutes) and chronic (days) time frames. These results demonstrate that Az-chitosan hydrogels are cytocompatible and mechanically suitable for use as bioadhesives in peripheral neurosurgeries.
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Affiliation(s)
- Todd A Rickett
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana 47907, United States
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Sander EA, Stylianopoulos T, Tranquillo RT, Barocas VH. Image-based biomechanics of collagen-based tissue equivalents. IEEE ENGINEERING IN MEDICINE AND BIOLOGY MAGAZINE : THE QUARTERLY MAGAZINE OF THE ENGINEERING IN MEDICINE & BIOLOGY SOCIETY 2009; 28:10-8. [PMID: 19457729 PMCID: PMC2762792 DOI: 10.1109/memb.2009.932486] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Edward A Sander
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, USA
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Affiliation(s)
- Hazel R.C. SCREEN
- Queen Mary University of London, School of Engineering and Materials Science
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