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Alharbi N, Guthold M. Mechanical properties of hydrated electrospun polycaprolactone (PCL) nanofibers. J Mech Behav Biomed Mater 2024; 155:106564. [PMID: 38749267 DOI: 10.1016/j.jmbbm.2024.106564] [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: 07/11/2023] [Revised: 04/18/2024] [Accepted: 04/26/2024] [Indexed: 05/28/2024]
Abstract
Polycaprolactone (PCL) nanofibers are a promising material for biomedical applications due to their biocompatibility, slow degradation rate, and thermal stability. We electrospun PCL fibers onto a striated substrate with 12 μm wide ridges and grooves and determined their mechanical properties in an aqueous solution with a combined atomic force/inverted optical microscopy technique. Fiber diameters, D, ranged from 27 to 280 nm. The hydrated PCL fibers had an extensibility (breaking strain), εmax, of 137%. The Young's modulus, E, and tensile strength, σT, showed a strong dependence on fiber diameter, D; decreasing steeply with increasing diameter, following empirical equations E(D)=(4.3∙103∙e-D51nm+1.1∙102) MPa and σT(D)=(2.6∙103∙e-D55nm+0.6∙102) MPa. Incremental stress-strain measurements were employed to investigate the viscoelastic behavior of these fibers. The fibers exhibited stress relaxation with a fast and slow relaxation time of 3.7 ± 1.2 s and 23 ± 8 s and these experiments also allowed the determination of the elastic and viscous moduli. Cyclic stress-strain curves were used to determine that the elastic limit of the fibers, εelastic, is between 19% and 36%. These curves were also used to determine that these fibers showed small energy losses (<20%) at small strains (ε < 10%), and over 50% energy loss at large strains (ε > 50%), asymptotically approaching 61%, as Eloss=61%·(1-e-0.04*ε). Our work is the first mechanical characterization of hydrated electrospun PCL nanofibers; all previous experiments were performed on dry PCL fibers, to which we will compare our data.
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Affiliation(s)
- Nouf Alharbi
- Department of Physics, Wake Forest University, Winston-Salem, NC, 27109, USA
| | - Martin Guthold
- Department of Physics, Wake Forest University, Winston-Salem, NC, 27109, USA; Center for Functional Materials, Wake Forest University, Winston-Salem, NC, 27109, USA.
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2
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Izadi R, Trovalusci P, Fantuzzi N. A Study on the Effect of Doping Metallic Nanoparticles on Fracture Properties of Polylactic Acid Nanofibres via Molecular Dynamics Simulation. NANOMATERIALS (BASEL, SWITZERLAND) 2023; 13:989. [PMID: 36985883 PMCID: PMC10056384 DOI: 10.3390/nano13060989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Revised: 03/05/2023] [Accepted: 03/07/2023] [Indexed: 06/18/2023]
Abstract
All-atom molecular dynamics simulations are conducted to elucidate the fracture mechanism of polylactic acid nanofibres doped with metallic nanoparticles. Extensional deformation is applied on polymer nanofibres decorated with spherical silver nanoparticles on the surface layer. In the obtained stress-strain curve, the elastic, yield, strain softening and fracture regions are recognized, where mechanical parameters are evaluated by tracking the stress, strain energy and geometrical evolutions. The energy release rate during crack propagation, which is a crucial factor in fracture mechanics, is calculated. The results show that the presence of doping nanoparticles improves the fracture properties of the polymer nanofibre consistently with experimental observation. The nanoparticles bind together polymer chains on the surface layer, which hinders crack initiation and propagation. The effect of the distribution of nanoparticles is studied through different doping decorations. Additionally, a discussion on the variation of internal energy components during uniaxial tensile loading is provided to unravel the deformation mechanism of nanoparticle-doped nanofibres.
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Affiliation(s)
- Razie Izadi
- Department of Structural and Geotechnical Engineering, Sapienza University of Rome, Via Gramsci 53, 00197 Rome, Italy;
| | - Patrizia Trovalusci
- Department of Structural and Geotechnical Engineering, Sapienza University of Rome, Via Gramsci 53, 00197 Rome, Italy;
| | - Nicholas Fantuzzi
- Department of Civil, Chemical, Environmental and Materials Engineering, University of Bologna, Viale del Risorgimento 2, 40136 Bologna, Italy;
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3
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Álvarez Z, Ortega JA, Sato K, Sasselli IR, Kolberg-Edelbrock AN, Qiu R, Marshall KA, Nguyen TP, Smith CS, Quinlan KA, Papakis V, Syrgiannis Z, Sather NA, Musumeci C, Engel E, Stupp SI, Kiskinis E. Artificial extracellular matrix scaffolds of mobile molecules enhance maturation of human stem cell-derived neurons. Cell Stem Cell 2023; 30:219-238.e14. [PMID: 36638801 PMCID: PMC9898161 DOI: 10.1016/j.stem.2022.12.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 11/04/2022] [Accepted: 12/13/2022] [Indexed: 01/13/2023]
Abstract
Human induced pluripotent stem cell (hiPSC) technologies offer a unique resource for modeling neurological diseases. However, iPSC models are fraught with technical limitations including abnormal aggregation and inefficient maturation of differentiated neurons. These problems are in part due to the absence of synergistic cues of the native extracellular matrix (ECM). We report on the use of three artificial ECMs based on peptide amphiphile (PA) supramolecular nanofibers. All nanofibers display the laminin-derived IKVAV signal on their surface but differ in the nature of their non-bioactive domains. We find that nanofibers with greater intensity of internal supramolecular motion have enhanced bioactivity toward hiPSC-derived motor and cortical neurons. Proteomic, biochemical, and functional assays reveal that highly mobile PA scaffolds caused enhanced β1-integrin pathway activation, reduced aggregation, increased arborization, and matured electrophysiological activity of neurons. Our work highlights the importance of designing biomimetic ECMs to study the development, function, and dysfunction of human neurons.
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Affiliation(s)
- Zaida Álvarez
- Simpson Querrey Institute for BioNanotechnology, Northwestern University, Chicago, IL 60611, USA; Department of Medicine, Northwestern University, Chicago, IL 60611, USA; Biomaterials for Regenerative Therapies, Institute for Bioengineering of Catalonia (IBEC), Barcelona 08028, Spain
| | - J Alberto Ortega
- The Ken & Ruth Davee Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA; Department of Pathology and Experimental Therapeutics, Faculty of Medicine and Health Sciences, University of Barcelona, L'Hospitalet de Llobregat, Barcelona 08907, Spain
| | - Kohei Sato
- Simpson Querrey Institute for BioNanotechnology, Northwestern University, Chicago, IL 60611, USA; Department of Chemistry, Northwestern University, Evanston, IL 60208, USA
| | - Ivan R Sasselli
- Simpson Querrey Institute for BioNanotechnology, Northwestern University, Chicago, IL 60611, USA; Department of Chemistry, Northwestern University, Evanston, IL 60208, USA; Center for Cooperative Research in Biomaterials (CIC biomaGUNE), Basque Research and Technology Alliance (BRTA), Donostia-San Sebastián 20014, Spain
| | - Alexandra N Kolberg-Edelbrock
- Simpson Querrey Institute for BioNanotechnology, Northwestern University, Chicago, IL 60611, USA; Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Ruomeng Qiu
- Simpson Querrey Institute for BioNanotechnology, Northwestern University, Chicago, IL 60611, USA; Department of Chemistry, Northwestern University, Evanston, IL 60208, USA
| | - Kelly A Marshall
- The Ken & Ruth Davee Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Thao Phuong Nguyen
- The Ken & Ruth Davee Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA; Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Cara S Smith
- Simpson Querrey Institute for BioNanotechnology, Northwestern University, Chicago, IL 60611, USA; Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Katharina A Quinlan
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, RI 02881, USA
| | - Vasileios Papakis
- The Ken & Ruth Davee Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Zois Syrgiannis
- Simpson Querrey Institute for BioNanotechnology, Northwestern University, Chicago, IL 60611, USA; Department of Chemistry, Northwestern University, Evanston, IL 60208, USA
| | - Nicholas A Sather
- Simpson Querrey Institute for BioNanotechnology, Northwestern University, Chicago, IL 60611, USA
| | - Chiara Musumeci
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Elisabeth Engel
- Biomaterials for Regenerative Therapies, Institute for Bioengineering of Catalonia (IBEC), Barcelona 08028, Spain
| | - Samuel I Stupp
- Simpson Querrey Institute for BioNanotechnology, Northwestern University, Chicago, IL 60611, USA; Department of Chemistry, Northwestern University, Evanston, IL 60208, USA; Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA; Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA; Department of Medicine, Northwestern University, Chicago, IL 60611, USA.
| | - Evangelos Kiskinis
- Simpson Querrey Institute for BioNanotechnology, Northwestern University, Chicago, IL 60611, USA; The Ken & Ruth Davee Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA; Department of Neuroscience, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA.
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4
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Chan FY, Kurosaki R, Ganser C, Takeda T, Uchihashi T. Tip-scan high-speed atomic force microscopy with a uniaxial substrate stretching device for studying dynamics of biomolecules under mechanical stress. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2022; 93:113703. [PMID: 36461522 DOI: 10.1063/5.0111017] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 10/09/2022] [Indexed: 06/17/2023]
Abstract
High-speed atomic force microscopy (HS-AFM) is a powerful tool for studying the dynamics of biomolecules in vitro because of its high temporal and spatial resolution. However, multi-functionalization, such as combination with complementary measurement methods, environment control, and large-scale mechanical manipulation of samples, is still a complex endeavor due to the inherent design and the compact sample scanning stage. Emerging tip-scan HS-AFM overcame this design hindrance and opened a door for additional functionalities. In this study, we designed a motor-driven stretching device to manipulate elastic substrates for HS-AFM imaging of biomolecules under controllable mechanical stimulation. To demonstrate the applicability of the substrate stretching device, we observed a microtubule buckling by straining the substrate and actin filaments linked by α-actinin on a curved surface. In addition, a BAR domain protein BIN1 that senses substrate curvature was observed while dynamically controlling the surface curvature. Our results clearly prove that large-scale mechanical manipulation can be coupled with nanometer-scale imaging to observe biophysical effects otherwise obscured.
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Affiliation(s)
- Feng-Yueh Chan
- Department of Physics, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan
| | - Ryo Kurosaki
- Department of Physics, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan
| | - Christian Ganser
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi 444-8787, Japan
| | - Tetsuya Takeda
- Faculty of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Kita-Ku, Okayama 700-8558, Japan
| | - Takayuki Uchihashi
- Department of Physics, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan
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5
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Multiscale Mechanical Performance of Wood: From Nano- to Macro-Scale across Structure Hierarchy and Size Effects. NANOMATERIALS 2022; 12:nano12071139. [PMID: 35407258 PMCID: PMC9000298 DOI: 10.3390/nano12071139] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 03/23/2022] [Accepted: 03/24/2022] [Indexed: 02/07/2023]
Abstract
This review describes methods and results of studying the mechanical properties of wood at all scales: from nano- to macro-scale. The connection between the mechanical properties of material and its structure at all these levels is explored. It is shown that the existing size effects in the mechanical properties of wood, in a range of the characteristic sizes of the structure of about six orders of magnitude, correspond to the empirical Hall-Petch relation. This “law” was revealed more than 60 years ago in metals and alloys and later in other materials. The nature, as well as the particular type of the size dependences in different classes of materials can vary, but the general trend, “the smaller the stronger”, remains true both for wood and for other cellulose-containing materials. The possible mechanisms of the size effects in wood are being discussed. The correlations between the mechanical and thermophysical properties of wood are described. Several examples are used to demonstrate the possibility to forecast the macromechanical properties of wood by means of contactless thermographic express methods based on measuring temperature diffusivity. The research technique for dendrochronological and dendroclimatological studies by means of the analysis of microhardness and Young’s modulus radial dependences in annual growth rings is described.
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6
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Ricaurte L, Perea-Flores MDJ, Méndez-Méndez JV, Santagapita PR, Quintanilla-Carvajal MX. Compound distribution, structural analysis and nanomechanical properties of nanofibers loaded with high-oleic palm oil nanoemulsions for packaging application. Colloids Surf A Physicochem Eng Asp 2022. [DOI: 10.1016/j.colsurfa.2021.128148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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7
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Monitoring fiber-like aggregation of collagen using gold nanoparticles as probes. CHEMICAL PAPERS 2021. [DOI: 10.1007/s11696-021-01935-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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8
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Taskin MB, Ahmad T, Wistlich L, Meinel L, Schmitz M, Rossi A, Groll J. Bioactive Electrospun Fibers: Fabrication Strategies and a Critical Review of Surface-Sensitive Characterization and Quantification. Chem Rev 2021; 121:11194-11237. [DOI: 10.1021/acs.chemrev.0c00816] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Mehmet Berat Taskin
- Department of Functional Materials in Medicine and Dentistry and Bavarian Polymer Institute, University of Würzburg, 97070 Würzburg, Germany
| | - Taufiq Ahmad
- Department of Functional Materials in Medicine and Dentistry and Bavarian Polymer Institute, University of Würzburg, 97070 Würzburg, Germany
| | - Laura Wistlich
- Department of Functional Materials in Medicine and Dentistry and Bavarian Polymer Institute, University of Würzburg, 97070 Würzburg, Germany
| | - Lorenz Meinel
- Institute of Pharmacy and Food Chemistry and Helmholtz Institute for RNA Based Infection Research, 97074 Würzburg, Germany
| | - Michael Schmitz
- Department of Functional Materials in Medicine and Dentistry and Bavarian Polymer Institute, University of Würzburg, 97070 Würzburg, Germany
| | - Angela Rossi
- Department of Functional Materials in Medicine and Dentistry and Bavarian Polymer Institute, University of Würzburg, 97070 Würzburg, Germany
| | - Jürgen Groll
- Department of Functional Materials in Medicine and Dentistry and Bavarian Polymer Institute, University of Würzburg, 97070 Würzburg, Germany
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9
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Jiang K, Wang L, Zhang X, Ma Z, Song Y, Zhang W. Side-Chain Length Dependence of Young’s Modulus and Strength in Crystalline Poly(3-alkylthiophene) Nanofibers. Macromolecules 2020. [DOI: 10.1021/acs.macromol.0c01975] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ke Jiang
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, P. R. China
| | - Liang Wang
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, P. R. China
- Institute of Theoretical Chemistry, College of Chemistry, Jilin University, Changchun 130012, P. R. China
| | - Xiaoye Zhang
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, P. R. China
| | - Ziwen Ma
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, P. R. China
| | - Yu Song
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, P. R. China
- Institute of Theoretical Chemistry, College of Chemistry, Jilin University, Changchun 130012, P. R. China
| | - Wenke Zhang
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, P. R. China
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10
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Nguyen-Truong M, Li YV, Wang Z. Mechanical Considerations of Electrospun Scaffolds for Myocardial Tissue and Regenerative Engineering. Bioengineering (Basel) 2020; 7:E122. [PMID: 33022929 PMCID: PMC7711753 DOI: 10.3390/bioengineering7040122] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 09/25/2020] [Accepted: 10/01/2020] [Indexed: 12/13/2022] Open
Abstract
Biomaterials to facilitate the restoration of cardiac tissue is of emerging importance. While there are many aspects to consider in the design of biomaterials, mechanical properties can be of particular importance in this dynamically remodeling tissue. This review focuses on one specific processing method, electrospinning, that is employed to generate materials with a fibrous microstructure that can be combined with material properties to achieve the desired mechanical behavior. Current methods used to fabricate mechanically relevant micro-/nanofibrous scaffolds, in vivo studies using these scaffolds as therapeutics, and common techniques to characterize the mechanical properties of the scaffolds are covered. We also discuss the discrepancies in the reported elastic modulus for physiological and pathological myocardium in the literature, as well as the emerging area of in vitro mechanobiology studies to investigate the mechanical regulation in cardiac tissue engineering. Lastly, future perspectives and recommendations are offered in order to enhance the understanding of cardiac mechanobiology and foster therapeutic development in myocardial regenerative medicine.
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Affiliation(s)
- Michael Nguyen-Truong
- School of Biomedical Engineering, Colorado State University, Fort Collins, CO 80523, USA; (M.N.-T.); (Y.V.L.)
| | - Yan Vivian Li
- School of Biomedical Engineering, Colorado State University, Fort Collins, CO 80523, USA; (M.N.-T.); (Y.V.L.)
- Department of Design and Merchandising, Colorado State University, Fort Collins, CO 80523, USA
- School of Advanced Materials Discovery, Colorado State University, Fort Collins, CO 80523, USA
| | - Zhijie Wang
- School of Biomedical Engineering, Colorado State University, Fort Collins, CO 80523, USA; (M.N.-T.); (Y.V.L.)
- Department of Mechanical Engineering, Colorado State University, Fort Collins, CO 80523, USA
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11
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Grue BH, Vincent LC, Kreplak L, Veres SP. Alternate soaking enables easy control of mineralized collagen scaffold mechanics from nano- to macro-scale. J Mech Behav Biomed Mater 2020; 110:103863. [PMID: 32957181 DOI: 10.1016/j.jmbbm.2020.103863] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 04/27/2020] [Accepted: 05/12/2020] [Indexed: 11/19/2022]
Abstract
The mechanical properties of biologic scaffolds are critical to cellular interactions and hence functional response within the body. In the case of scaffolds for bone tissue regeneration, engineered scaffolds created by combining collagen with inorganic mineral are increasingly being explored, due to their favourable structural and chemical characteristics. Development of a method for controlling the mechanics of these scaffolds could lead to significant additional advantages by harnessing the intrinsic mechnotransduction pathways of stem cells via appropriate control of scaffold mechanical properties. Here we present a method for controlling the macroscale flexural modulus of mineralized collagen sheets, and the radial indentation modulus of the sheets' constituent collagen fibrils. Scaffolds were created starting with sheets of highly aligned, natively structured collagen fibrils, prepared via cryosectioning of decellularized tendon. Sheets underwent an alternate soaking mineralization procedure, with sequential exposure to citrate-doped calcium and carbonate-containing phosphate solutions, both of which included poly aspartic acid. The extent of scaffold mineralization was controlled via number of repeated mineralization cycles: 0 (unmineralized), 5, 10, and 20 cycles were trialed. Following scaffold preparation, ultrastructure, macroscale flexural modulus, and nanoscale indentation modulus were assessed. Surface architecture studied by SEM, and inspection of individual extracted fibrils by TEM and AFM confirmed that fibrils became increasingly laden with mineral as the number of mineralization cycles increased. Measurements of collagen fibril nanomechanics using AFM showed that the radial modulus of collagen fibrils increased linearly with mineralization cycles completed, from 215 ± 125 MPa for fibrils from unmineralized (0 cycle) scaffolds to 778 ± 302 MPa for fibrils from the 20 mineralization cycle scaffolds. Measurements of scaffold macromechanics via flexural testing also showed a linear increase in flexural modulus with increasing number of mineralization cycles completed, from 18 ± 7 MPa for the 5 cycle scaffolds to 156 ± 50 MPa for the 20 cycle scaffolds. The process detailed herein provides a way to create mineralized collagen scaffolds with easily controllable mechanical properties.
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Affiliation(s)
- Brendan H Grue
- Division of Engineering, Saint Mary's University, Halifax, Nova Scotia, Canada
| | - Luke C Vincent
- Division of Engineering, Saint Mary's University, Halifax, Nova Scotia, Canada
| | - Laurent Kreplak
- Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia, Canada; School of Biomedical Engineering, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Samuel P Veres
- Division of Engineering, Saint Mary's University, Halifax, Nova Scotia, Canada; School of Biomedical Engineering, Dalhousie University, Halifax, Nova Scotia, Canada.
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12
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Ju D, Zhang Y, Li R, Liu S, Li L, Chen H. Mechanism-Independent Manipulation of Single-Wall Carbon Nanotubes with Atomic Force Microscopy Tip. NANOMATERIALS (BASEL, SWITZERLAND) 2020; 10:E1494. [PMID: 32751468 PMCID: PMC7466456 DOI: 10.3390/nano10081494] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 07/25/2020] [Accepted: 07/28/2020] [Indexed: 11/20/2022]
Abstract
Atomic force microscopy (AFM) based nanomanipulation can align the orientation and position of individual carbon nanotubes accurately. However, the flexible deformation during the tip manipulation modifies the original shape of these nanotubes, which could affect its electrical properties and reduce the accuracy of AFM nanomanipulation. Thus, we developed a protocol for searching the synergistic parameter combinations to push single-wall carbon nanotubes (SWCNTs) to maintain their original shape after manipulation as far as possible, without requiring the sample physical properties and the tip-manipulation mechanisms. In the protocol, from a vast search space of manipulating parameters, the differential evolution (DE) algorithm was used to identify the optimal combinations of three parameters rapidly with the DE algorithm and the feedback of the length ratio of SWCNTs before and after manipulation. After optimizing the scale factor F and crossover probability Cr, the values F = 0.4 and Cr = 0.6 were used, and the ratio could reach 0.95 within 5-7 iterations. A parameter region with a higher length ratio was also studied to supply arbitrary pushing parameter combinations for individual manipulation demand. The optimal pushing parameter combination reduces the manipulation trajectory and the tip abrasion, thereby significantly improving the efficiency of tip manipulation for nanowire materials. The protocol for searching the best parameter combinations used in this study can also be extended to manipulate other one-dimensional nanomaterials.
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Affiliation(s)
| | | | | | | | - Longhai Li
- College of Engineering, Northeast Agricultural University, Harbin 150030, China; (D.J.); (Y.Z.); (R.L.); (S.L.)
| | - Haitao Chen
- College of Engineering, Northeast Agricultural University, Harbin 150030, China; (D.J.); (Y.Z.); (R.L.); (S.L.)
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13
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Liu Y, Sokolov I, Dokukin ME, Xiong Y, Peng P. Can AFM be used to measure absolute values of Young's modulus of nanocomposite materials down to the nanoscale? NANOSCALE 2020; 12:12432-12443. [PMID: 32495797 DOI: 10.1039/d0nr02314k] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
At present, a technique potentially capable of measuring values of Young's modulus at the nanoscale is atomic force microscopy (AFM) working in the indentation mode. However, the question if AFM indentation data can be translated into absolute values of the modulus is not well-studied as yet, in particular, for the most interesting case of stiff nanocomposite materials. Here we investigate this question. A special sample of nanocomposite material, shale rock, was used, which is relatively homogeneous at the multi-micron scale. Two AFM modes, force-volume and PeakForce QNM were used in this study. The nanoindentation technique was used as a control benchmark for the measurement of effective Young's modulus of the shale sample. The indentation rate was carefully controlled. To ensure the self-consistency of the mechanical model used to analyze AFM data, the model was modified to take into account the presence of the surface roughness. We found excellent agreement between the average values of effective Young's modulus calculated within AFM and the nanoindenter benchmark method. At the same time, the softest and hardest areas of the sample were seen only with AFM.
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Affiliation(s)
- Yuke Liu
- Department of Mechanical Engineering, Tufts University, Medford, MA, USA.
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14
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Fang Z, Geng Y, Wang J, Yan Y, Zhang G. Mechanical properties of gold nanowires prepared by nanoskiving approach. NANOSCALE 2020; 12:8194-8199. [PMID: 32255141 DOI: 10.1039/d0nr01049a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The nanoskiving method based on nanocutting process is a new, low cost and easy way to machine nanowires. In this study, this technique is used to machine Au nanowires with different cutting directions and depths. Young's modulus and the yield strength of nanowires are then measured by an atomic force microscope-based three-point bending test. Results show that the Young's modulus of nanowires is independent of size and is not affected by cutting directions. However, the yield strength of nanowires machined by parallel cutting (NWs-b) is 42-64% higher than that machined by perpendicular cutting (NWs-a).
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Affiliation(s)
- Zhuo Fang
- Key Laboratory of Micro-systems and Micro-structures Manufacturing of Ministry of Education, Harbin Institute of Technology, Harbin, Heilongjiang 150001, China.
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15
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Role of nanofibers on MSCs fate: Influence of fiber morphologies, compositions and external stimuli. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2020; 107:110218. [DOI: 10.1016/j.msec.2019.110218] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Revised: 09/04/2019] [Accepted: 09/16/2019] [Indexed: 01/09/2023]
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16
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Jiang K, Xu D, Ma Z, Yang P, Song Y, Zhang W. Quantifying the Mechanical Anisotropy in Poly(3-hexylthiophene) Nanofibers. ACS Macro Lett 2020; 9:108-114. [PMID: 35638666 DOI: 10.1021/acsmacrolett.9b00866] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Correlating the structure with nanomechanical property of semicrystalline conjugated-polymer crystal is of essential importance for the performance improvement and design of flexible electronic devices. Although it is well-known that the semicrystalline conjugated-polymer crystal exhibits anisotropic structure owing to the π-π and layer stacking of highly coplanar conjugated backbones, the structure-nanomechanical property relationship is missing. Here, we investigated the axial mechanical anisotropy of the P3HT nanofiber by using thermal shape-fluctuation analysis and a three-point bending test based on atomic force microscopy. Our results show that Young's modulus in the layer-stacking direction (EL) is 1-2 orders of magnitude greater than that in the π-conjugated backbone direction (EB). We attribute this mechanical anisotropy to the π-stacking of the P3HT backbone, but the layer stacking will decrease EL, which weakens the mechanical anisotropy. Moreover, we demonstrated that the P3HT nanofiber shows a loading-rate-independent Young's modulus and deformation-dependent resilience in the layer-stacking direction.
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Affiliation(s)
- Ke Jiang
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, P. R. China
| | - Daren Xu
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, P. R. China.,Institute of Theoretical Chemistry, College of Chemistry, Jilin University, Changchun 130012, P. R. China
| | - Ziwen Ma
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, P. R. China
| | - Peng Yang
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, P. R. China
| | - Yu Song
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, P. R. China.,Institute of Theoretical Chemistry, College of Chemistry, Jilin University, Changchun 130012, P. R. China
| | - Wenke Zhang
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, P. R. China
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17
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On the Nanoscale Mapping of the Mechanical and Piezoelectric Properties of Poly (L-Lactic Acid) Electrospun Nanofibers. APPLIED SCIENCES-BASEL 2020. [DOI: 10.3390/app10020652] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The effect of the post-annealing process on different properties of poly (L-lactic acid) (PLLA) nanofibers has been investigated in view of their use in energy-harvesting devices. Polymeric PLLA nanofibers were prepared by using electrospinning and then were thermally treated above their glass transition. A detailed comparison between as-spun (amorphous) and annealed (semi-crystalline) samples was performed in terms of the crystallinity, morphology and mechanical as well as piezoelectric properties using a multi-technique approach combining DSC, XRD, FTIR, and AFM measurements. A significant increase in the crystallinity of PLLA nanofibers has been observed after the post-annealing process, together with a major improvement of the mechanical and piezoelectric properties.
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18
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Sugimoto R, Lee JH, Lee JH, Jin HE, Yoo SY, Lee SW. Bacteriophage nanofiber fabrication using near field electrospinning. RSC Adv 2019; 9:39111-39118. [PMID: 35540674 PMCID: PMC9075989 DOI: 10.1039/c9ra07510k] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Accepted: 11/08/2019] [Indexed: 12/11/2022] Open
Abstract
M13 bacteriophage (phage) nano- and microfibers were fabricated using electrospinning. Using liquid crystalline suspension of the phage, we successfully fabricated nano- and microscale pure phage fibers. Through a near field electrospinning process, we fabricated the desired phage fiber pattern with tunable direction and spacing. In addition, we demonstrated that the resulting phage fibers could be utilized as an electrostatic-stimulus responsive actuator. The near field electrospinning would be a very useful tool to design phage-based chemical sensors, tissue regenerative materials, energy generators, metallic and semiconductor nanowires in the future.
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Affiliation(s)
- Ryota Sugimoto
- Department of Bioengineering, University of California at Berkeley Berkeley CA 94720 USA
- Biological Systems and Engineering, Lawrence Berkeley National Laboratory Berkeley CA 94720 USA
| | - Ju Hun Lee
- Department of Bioengineering, University of California at Berkeley Berkeley CA 94720 USA
- Biological Systems and Engineering, Lawrence Berkeley National Laboratory Berkeley CA 94720 USA
| | - Ju-Hyuck Lee
- Department of Bioengineering, University of California at Berkeley Berkeley CA 94720 USA
- Biological Systems and Engineering, Lawrence Berkeley National Laboratory Berkeley CA 94720 USA
| | - Hyo-Eon Jin
- Department of Bioengineering, University of California at Berkeley Berkeley CA 94720 USA
- Biological Systems and Engineering, Lawrence Berkeley National Laboratory Berkeley CA 94720 USA
| | - So Young Yoo
- BIO-IT Foundry Technology Institute, Pusan National University Busan 609-735 Republic of Korea
- Research Institute for Convergence of Biomedical Science and Technology Yangsan 626-770 Republic of Korea
| | - Seung-Wuk Lee
- Department of Bioengineering, University of California at Berkeley Berkeley CA 94720 USA
- Biological Systems and Engineering, Lawrence Berkeley National Laboratory Berkeley CA 94720 USA
- Tsinghua Berkeley Shenzhen Institute Berkeley USA
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19
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Tung WT, Wang W, Liu Y, Gould OEC, Kratz K, Ma N, Lendlein A. Mechanical characterization of electrospun polyesteretherurethane (PEEU) meshes by atomic force microscopy. Clin Hemorheol Microcirc 2019; 73:229-236. [PMID: 31561331 DOI: 10.3233/ch-199201] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The mechanical properties of electrospun fiber meshes typically are measured by tensile testing at the macro-scale without precisely addressing the spatial scale of living cells and their submicron architecture. Atomic force microscopy (AFM) enables the examination of the nano- and micro-mechanical properties of the fibers with potential to correlate the structural mechanical properties across length scales with composition and functional behavior. In this study, a polyesteretherurethane (PEEU) polymer containing poly(p-dioxanone) (PPDO) and poly(ɛ-caprolactone) (PCL) segments was electrospun into fiber meshes or suspended single fibers. We employed AFM three point bending testing and AFM force mapping to measure the elastic modulus and stiffness of individual micro/nanofibers and the fiber mesh. The local stiffness of the fiber mesh including the randomized, intersecting structure was also examined for each individual fiber. Force mapping results with a set point of 50 nN demonstrated the dependence of the elasticity of a single fiber on the fiber mesh architecture. The non-homogeneous stiffness along the same fiber was attributed to the intersecting structure of the supporting mesh morphology. The same fiber measured at a point with and without axial fiber support showed a remarkable difference in stiffness, ranging from 0.2 to 10 nN/nm respectively. For the region, where supporting fibers densely intersected, the stiffness was found to be considerably higher. In the region where the degrees of freedom of the fibers was not restricted, allowing greater displacement, the stiffness were observed to be lower. This study elucidates the relationship between architecture and the mechanical properties of a micro/nanofiber mesh. By providing a greater understanding of the role of spatial arrangement and organization on the surface mechanical properties of such materials, we hope to provide insight into the design of microenvironments capable of regulating cell functionality.
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Affiliation(s)
- Wing Tai Tung
- Institute of Biomaterial Science and Berlin-Brandenburg Centre for Regenerative Therapies, Helmholtz-Zentrum Geesthacht, Teltow, Germany.,Institute of Chemistry, University of Potsdam, Potsdam, Germany
| | - Weiwei Wang
- Institute of Biomaterial Science and Berlin-Brandenburg Centre for Regenerative Therapies, Helmholtz-Zentrum Geesthacht, Teltow, Germany
| | - Yue Liu
- Institute of Biomaterial Science and Berlin-Brandenburg Centre for Regenerative Therapies, Helmholtz-Zentrum Geesthacht, Teltow, Germany
| | - Oliver E C Gould
- Institute of Biomaterial Science and Berlin-Brandenburg Centre for Regenerative Therapies, Helmholtz-Zentrum Geesthacht, Teltow, Germany
| | - Karl Kratz
- Institute of Biomaterial Science and Berlin-Brandenburg Centre for Regenerative Therapies, Helmholtz-Zentrum Geesthacht, Teltow, Germany
| | - Nan Ma
- Institute of Biomaterial Science and Berlin-Brandenburg Centre for Regenerative Therapies, Helmholtz-Zentrum Geesthacht, Teltow, Germany.,Institute of Chemistry and Biochemistry, Free University of Berlin, Berlin, Germany
| | - Andreas Lendlein
- Institute of Biomaterial Science and Berlin-Brandenburg Centre for Regenerative Therapies, Helmholtz-Zentrum Geesthacht, Teltow, Germany.,Institute of Chemistry, University of Potsdam, Potsdam, Germany.,Institute of Chemistry and Biochemistry, Free University of Berlin, Berlin, Germany
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20
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Morel A, Oberle SC, Ulrich S, Yazgan G, Spano F, Ferguson SJ, Fortunato G, Rossi RM. Revealing non-crystalline polymer superstructures within electrospun fibers through solvent-induced phase rearrangements. NANOSCALE 2019; 11:16788-16800. [PMID: 31465059 DOI: 10.1039/c9nr04432a] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The design of nanofibers for biomedical applications requires a deep understanding of the fiber formation process and the resulting internal structure. In this regard, non-crystalline, mesomorphic structures play a central role in the processing of many polymers as precursors in the formation of crystalline superstructures (e.g. shish-kebab) and influence strongly the physical properties of polymers with a low degree of crystallinity. Yet, our ability to probe these relevant features is often greatly limited by their low contrast differences with the amorphous phase. We present an approach to reveal the organization of the mesomorphic superstructures within such polymeric materials, on the example of electrospun poly(l-lactide) nanofibers. Based on solvent-induced crystallization, this method employs fine-tuned solvent/non-solvent systems to enhance the contrast of these structural features by selectively triggering and controlling reorganization of the phases. Hereby, the mesomorphic regions are transformed into an α-crystalline phase, while the nanoscale spatial arrangement of the underlying superstructures is preserved. Combined with X-ray analytical techniques and electron microscopy, our approach provides detailed insights into the nanofiber's inner architecture, allowing for its direct visualization. Thereby, the influence of electrospinning parameters on the fiber formation process is explained as well as the impact of the resulting non-crystalline superstructures on single fiber mechanical properties. The method can be applied to comparable polymers for the development of materials with controlled, tailored properties.
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Affiliation(s)
- Alexandre Morel
- Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Biomimetic Membranes and Textiles, 9014 St Gallen, Switzerland.
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21
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Omidinia-Anarkoli A, Rimal R, Chandorkar Y, Gehlen DB, Rose JC, Rahimi K, Haraszti T, De Laporte L. Solvent-Induced Nanotopographies of Single Microfibers Regulate Cell Mechanotransduction. ACS APPLIED MATERIALS & INTERFACES 2019; 11:7671-7685. [PMID: 30694648 DOI: 10.1021/acsami.8b17955] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The extracellular matrix (ECM) is a dynamic three-dimensional (3D) fibrous network, surrounding all cells in vivo. Fiber manufacturing techniques are employed to mimic the ECM but still lack the knowledge and methodology to produce single fibers approximating cell size with different surface topographies to study cell-material interactions. Using solvent-assisted spinning (SAS), the potential to continuously produce single microscale fibers with unlimited length, precise diameter, and specific surface topographies was demonstrated. By applying solvents with different solubilities and volatilities, fibers with smooth, grooved, and porous surface morphologies are produced. Due to their hierarchical structures, the porous fibers are the most hydrophobic, followed by the grooved and the smooth fibers. The fiber diameter is increased by increasing the polymer concentration or decreasing the collector rotational speed. Moreover, SAS offers the advantage to control the interfiber distance and angle to fabricate multilayered 3D constructs. This report shows for the first time that the micro- and nanoscale topographies of single fibers mechanically regulate cell behavior. Fibroblasts, grown on fibers with grooved topographical features, stretch and elongate more compared to smooth and porous fibers, whereas both porous and grooved fibers induce nuclear translocation of yes-associated protein. The presented technique, therefore, provides a unique platform to study the interaction between cells and single ECM-like fibers in a precise and reproducible manner, which is of great importance for new material developments in the field of tissue engineering.
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Affiliation(s)
| | - Rahul Rimal
- DWI-Leibniz Institute for Interactive Materials , Aachen 52074 , Germany
| | - Yashoda Chandorkar
- DWI-Leibniz Institute for Interactive Materials , Aachen 52074 , Germany
| | - David B Gehlen
- DWI-Leibniz Institute for Interactive Materials , Aachen 52074 , Germany
| | - Jonas C Rose
- DWI-Leibniz Institute for Interactive Materials , Aachen 52074 , Germany
| | - Khosrow Rahimi
- DWI-Leibniz Institute for Interactive Materials , Aachen 52074 , Germany
| | - Tamás Haraszti
- DWI-Leibniz Institute for Interactive Materials , Aachen 52074 , Germany
| | - Laura De Laporte
- DWI-Leibniz Institute for Interactive Materials , Aachen 52074 , Germany
- ITMC-Institute of Technical and Macromolecular Chemistry , RWTH Aachen University , Aachen 52074 , Germany
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22
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Huang Q, Wang H, Gao H, Cheng P, Zhu L, Wang C, Yang Y. In Situ Observation of Amyloid Nucleation and Fibrillation by FastScan Atomic Force Microscopy. J Phys Chem Lett 2019; 10:214-222. [PMID: 30543438 DOI: 10.1021/acs.jpclett.8b03143] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Amyloidogenic proteins are key components in various amyloid diseases. The aggregation process and the local structural changes of the toxic species from toxic oligomers to protofibrils and subsequently to mature fibrils are crucial for understanding the molecular mechanism of the amyloidgenic process and also for developing a treatment strategy. Exploration on amyloid aggregation dynamics in situ under real liquid condition is feasible for reflection of the whole process with biological correlations. Herein we report the in situ dynamic study and structure exploration of Amylin1-37 aggregation by FastScan atomic force microscopy. Amylin1-37 nucleation process was observed in which smaller oligomers or monomers were assimilated by the surrounding big oligomers. Amylin1-37 protofibril aggregation was positively correlated with monomer concentration, whereas no direct relationship was observed between fibril elongation and monomer concentration. Growing end and passivated end were found during Amylin1-37 fibrillation. In the assembly process, the growing end kept its structure, and its stiffness was lower than the aggregate body, whereas the passivated end might experience rearrangements of β-structures, which eventually enabled fibril growth from this end. This work is beneficial to the insights of amyloid fibrillation and may shed light on the development of drugs targeting the specific phase of amyloid aggregation.
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Affiliation(s)
- Qunxing Huang
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Key Laboratory of Biological Effects of Nanomaterials and Nanosafety, CAS Center for Excellence in Nanoscience , National Center for Nanoscience and Technology , Beijing 100190 , China
- University of Chinese Academy of Sciences , 19 A Yuquan Rd , Shijingshan District, Beijing 100049 , China
| | - Huayi Wang
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Key Laboratory of Biological Effects of Nanomaterials and Nanosafety, CAS Center for Excellence in Nanoscience , National Center for Nanoscience and Technology , Beijing 100190 , China
- University of Chinese Academy of Sciences , 19 A Yuquan Rd , Shijingshan District, Beijing 100049 , China
| | - Houqian Gao
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Key Laboratory of Biological Effects of Nanomaterials and Nanosafety, CAS Center for Excellence in Nanoscience , National Center for Nanoscience and Technology , Beijing 100190 , China
- University of Chinese Academy of Sciences , 19 A Yuquan Rd , Shijingshan District, Beijing 100049 , China
| | - Peng Cheng
- State Key Laboratory of Tribology, Department of Mechanical Engineering , Tsinghua University , Beijing 100084 , China
| | - Ling Zhu
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Key Laboratory of Biological Effects of Nanomaterials and Nanosafety, CAS Center for Excellence in Nanoscience , National Center for Nanoscience and Technology , Beijing 100190 , China
- University of Chinese Academy of Sciences , 19 A Yuquan Rd , Shijingshan District, Beijing 100049 , China
| | - Chen Wang
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Key Laboratory of Biological Effects of Nanomaterials and Nanosafety, CAS Center for Excellence in Nanoscience , National Center for Nanoscience and Technology , Beijing 100190 , China
- University of Chinese Academy of Sciences , 19 A Yuquan Rd , Shijingshan District, Beijing 100049 , China
| | - Yanlian Yang
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Key Laboratory of Biological Effects of Nanomaterials and Nanosafety, CAS Center for Excellence in Nanoscience , National Center for Nanoscience and Technology , Beijing 100190 , China
- University of Chinese Academy of Sciences , 19 A Yuquan Rd , Shijingshan District, Beijing 100049 , China
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23
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Morel A, Domaschke S, Urundolil Kumaran V, Alexeev D, Sadeghpour A, Ramakrishna S, Ferguson S, Rossi R, Mazza E, Ehret A, Fortunato G. Correlating diameter, mechanical and structural properties of poly(l-lactide) fibres from needleless electrospinning. Acta Biomater 2018; 81:169-183. [PMID: 30273744 DOI: 10.1016/j.actbio.2018.09.055] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 08/16/2018] [Accepted: 09/27/2018] [Indexed: 10/28/2022]
Abstract
The development and application of nanofibres requires a thorough understanding of the mechanical properties on a single fibre level including respective modelling tools for precise fibre analysis. This work presents a mechanical and morphological study of poly-l-lactide nanofibres developed by needleless electrospinning. Atomic force microscopy (AFM) and micromechanical testing (MMT) were used to characterise the mechanical response of the fibres within a diameter range of 200-1400 nm. Young's moduli E determined by means of both methods are in sound agreement and show a strong increase for thinner fibres below a critical diameter of 800 nm. Similar increasing trends for yield stress and hardening modulus were measured by MMT. Finite element analyses show that the common practice of modelling three-point bending tests with either double supported or double clamped beams is prone to significant bias in the determined elastic properties, and that the latter is a good approximation only for small diameters. Therefore, an analytical formula based on intermediate boundary conditions is proposed that is valid for the whole tested range of fibre diameters, providing a consistently low error in axial Young's modulus below 10%. The analysis of fibre morphology by differential scanning calorimetry and 2D wide-angle X-ray scattering revealed increasing polymer chains alignment in the amorphous phase and higher crystallinity of fibres for decreasing diameter. The combination of these observations with the mechanical characterisation suggests a linear relationship between Young's modulus and both crystallinity and molecular orientation in the amorphous phase. STATEMENT OF SIGNIFICANCE: Fibrous membranes have rapidly growing use in various applications, each of which comes with specific property requirements. However, the development and production of nanofibre membranes with dedicated mechanical properties is challenging, in particular with techniques suitable for industrial scales such as needleless electrospinning. It is therefore a key step to understand the mechanical and structural characteristics of single nanofibres developed in this process, and to this end, the present work presents changes of internal fibre structure and mechanical properties with diameter, based on dedicated models. Special attention was given to the commonly used models for analyzing Young's modulus of single nanofibers in three-point bending tests, which are shown to be prone to large errors, and an improved robust approach is proposed.
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24
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Schulze M, Rogge M, Stark RW. Atomic force microscopy measurements probing the mechanical properties of single collagen fibrils under the influence of UV light in situ. J Mech Behav Biomed Mater 2018; 88:415-421. [PMID: 30216931 DOI: 10.1016/j.jmbbm.2018.08.039] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Revised: 06/06/2018] [Accepted: 08/27/2018] [Indexed: 11/27/2022]
Abstract
Collagen plays a decisive role as a functional substrate in tissue engineering. In particular, the rigidity of the collagen influences the behaviour of the attached cells. Thus, modification and controlled adjustment of collagen's characteristics are essential. To this end, controlled exposure to ultraviolet (UV) light is a promising process because it can be temporally and spatially well defined. In this study, we investigated the effect of UV exposure on surface supported single collagen fibrils in situ. This procedure allowed for a direct comparison between the untreated and modified states of type I collagen. Atomic force microscopy was used to map the mechanical properties. Exposure to UV light was used to influence the mechanical properties of the fibrils in varied liquid environments (deionized water and phosphate-buffered saline (PBS)). The results led to the assumption that combined UV/thermal treatment in deionized water continuously lowers the elastic modulus. In contrast, experiments performed in PBS-based solutions in combination with UV-B and UV-C light or thermal treatment up to 45 °C suggested an increase in the modulus within the first 30-40 min that subsequently decreased again. Thus, the wavelength, exposure, temperature, and chemical environment are relevant parameters that need to be controlled when modifying collagen using UV light.
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Affiliation(s)
- Marcus Schulze
- Physics of Surfaces, Institute of Materials Science, Technische Universität Darmstadt, Alarich-Weiss-Str. 16, 64287 Darmstadt, Germany; Center of Smart Interfaces, Technische Universität Darmstadt, Alarich-Weiss-Str. 10, 64287 Darmstadt, Germany
| | - Melanie Rogge
- Physics of Surfaces, Institute of Materials Science, Technische Universität Darmstadt, Alarich-Weiss-Str. 16, 64287 Darmstadt, Germany; Center of Smart Interfaces, Technische Universität Darmstadt, Alarich-Weiss-Str. 10, 64287 Darmstadt, Germany
| | - Robert W Stark
- Physics of Surfaces, Institute of Materials Science, Technische Universität Darmstadt, Alarich-Weiss-Str. 16, 64287 Darmstadt, Germany; Center of Smart Interfaces, Technische Universität Darmstadt, Alarich-Weiss-Str. 10, 64287 Darmstadt, Germany.
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25
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Son YJ, Kim HS, Mao W, Park JB, Lee D, Lee H, Yoo HS. Hydro-nanofibrous mesh deep cell penetration: a strategy based on peeling of electrospun coaxial nanofibers. NANOSCALE 2018; 10:6051-6059. [PMID: 29546898 DOI: 10.1039/c7nr04928e] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
A two-step strategy for coaxial electrospinning and postelectrospinning is an effective method for fabricating superfine nanofibers composed of highly swellable hydrogels. Alginate and poly(ε-caprolactone) [PCL] were coelectrospun via fibrous meshes with a coaxial nozzle; alginate at the core was subsequently cross-linked in calcium chloride solution. The PCL sheath was removed from the meshes by repeated organic-phase washing. The peeling process was monitored by scanning electron microscopy, transmission electron microscopy, and differential scanning calorimetry, and the complete removal of the PCL outer layers was confirmed by the thinning of the fiber volume. The obtained alginate hydronanofiber showed extreme water-swellability and mass erosion depending on the degree of cross-linking. We also measured the nanoscale and macroscale mechanical properties of a single nanofiber and of the whole mesh by atomic force microscopy and rheometry. Quantitative analysis of nanomechanical properties indicated that the hydronanofiber with higher cross-linking density had higher stiffness and Derjaguin-Müller-Toporov modulus. Cells laid on the mesh and the vertical infiltration distance were visualized and quantified by confocal laser scanning microscopy. Cells on the mesh with higher cross-linking density infiltrated deeply to the bottom of the mesh. Thus, hydrogel-like nanofibrous meshes are versatile matrices allowing for deep infiltration of cells throughout the mesh via manipulation of the mechanical properties of the nanofiber.
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Affiliation(s)
- Y J Son
- Department of Medical Biomaterials Engineering, Kangwon National University, Chuncheon 24341, Republic of Korea
| | - H S Kim
- Department of Biomedical Engineering, Columbia University, New York, NY 10027, USA
| | - W Mao
- Department of Medical Biomaterials Engineering, Kangwon National University, Chuncheon 24341, Republic of Korea
| | - J B Park
- Jeonju Center, Korea Basic Science Institute, Jeonju 54907, Republic of Korea
| | - D Lee
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Daejeon 34141, Republic of Korea
| | - H Lee
- Department of Chemistry, KI NanoCentury, Korea Advanced Institute of Science and Technology, 291 University Rd., Daejeon 34141, Republic of Korea
| | - H S Yoo
- Department of Medical Biomaterials Engineering, Kangwon National University, Chuncheon 24341, Republic of Korea and Institute of Bioscience and Biotechnology, Kangwon National University, Chuncheon 24341, Republic of Korea.
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26
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Dehnert M, Magerle R. 3D depth profiling of the interaction between an AFM tip and fluid polymer solutions. NANOSCALE 2018. [PMID: 29532845 DOI: 10.1039/c8nr00299a] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
In the atomic force microscopy (AFM) investigation of soft polymers and liquids, the tip-sample interaction is dominated by long-range van der Waals forces, capillary forces and adhesion. Furthermore, the tip can indent several tens of nanometres into the surface, and it can pull off a polymer filament from the surface. Therefore, measuring the unperturbed shape of a polymeric fluid can be challenging. Here, we study the tip-sample interaction with polystyrene droplets swollen in chloroform vapour, where we can utilize the solvent vapour concentration to adjust the specimen's mechanical properties from a stiff solid to a fluid film. With the same AFM tip, we use two different AFM force spectroscopy methods to measure three-dimensional (3D) depth profiles of the tip-sample interaction: force-distance (FD) curves and amplitude-phase-distance (APD) curves. The 3D depth profiles reconstructed from FD and APD measurements provide detailed insight into the tip-sample interaction mechanism for a fluid polymer solution. The fluid's intrinsic relaxation time, which we measure with an AFM-based step-strain experiment, is essential for understanding the tip-sample interaction mechanism. Furthermore, measuring 3D depth profiles and using APD data to reconstruct the unperturbed surface comprise a versatile methodology for obtaining accurate dimensional measurements of fluid and gel-like objects on the nanometre scale.
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Affiliation(s)
- Martin Dehnert
- Fakultät für Naturwissenschaften, Technische Universität Chemnitz, D-09107 Chemnitz, Germany.
| | - Robert Magerle
- Fakultät für Naturwissenschaften, Technische Universität Chemnitz, D-09107 Chemnitz, Germany.
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27
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Jahanmard-Hosseinabadi F, Amani-Tehran M, Eslaminejad MB. Mathematical Modeling and Experimental Evaluation for the predication of single nanofiber modulus. J Mech Behav Biomed Mater 2018; 79:38-45. [DOI: 10.1016/j.jmbbm.2017.12.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2017] [Revised: 12/06/2017] [Accepted: 12/08/2017] [Indexed: 12/22/2022]
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28
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Nautiyal P, Alam F, Balani K, Agarwal A. The Role of Nanomechanics in Healthcare. Adv Healthc Mater 2018; 7. [PMID: 29193838 DOI: 10.1002/adhm.201700793] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Revised: 09/18/2017] [Indexed: 12/21/2022]
Abstract
Nanomechanics has played a vital role in pushing our capability to detect, probe, and manipulate the biological species, such as proteins, cells, and tissues, paving way to a deeper knowledge and superior strategies for healthcare. Nanomechanical characterization techniques, such as atomic force microscopy, nanoindentation, nanotribology, optical tweezers, and other hybrid techniques have been utilized to understand the mechanics and kinetics of biospecies. Investigation of the mechanics of cells and tissues has provided critical information about mechanical characteristics of host body environments. This information has been utilized for developing biomimetic materials and structures for tissue engineering and artificial implants. This review summarizes nanomechanical characterization techniques and their potential applications in healthcare research. The principles and examples of label-free detection of cancers and myocardial infarction by nanomechanical cantilevers are discussed. The vital importance of nanomechanics in regenerative medicine is highlighted from the perspective of material selection and design for developing biocompatible scaffolds. This review interconnects the advancements made in fundamental materials science research and biomedical technology, and therefore provides scientific insight that is of common interest to the researchers working in different disciplines of healthcare science and technology.
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Affiliation(s)
- Pranjal Nautiyal
- Nanomechanics and Nanotribology Laboratory Florida International University 10555 West Flagler Street Miami FL 33174 USA
| | - Fahad Alam
- Biomaterials Processing and Characterization Laboratory Department of Materials Science and Engineering Indian Institute of Technology Kanpur Kanpur 208016 India
| | - Kantesh Balani
- Biomaterials Processing and Characterization Laboratory Department of Materials Science and Engineering Indian Institute of Technology Kanpur Kanpur 208016 India
| | - Arvind Agarwal
- Nanomechanics and Nanotribology Laboratory Florida International University 10555 West Flagler Street Miami FL 33174 USA
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Zhu S, Yuan Q, Yin T, You J, Gu Z, Xiong S, Hu Y. Self-assembly of collagen-based biomaterials: preparation, characterizations and biomedical applications. J Mater Chem B 2018; 6:2650-2676. [DOI: 10.1039/c7tb02999c] [Citation(s) in RCA: 103] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
By combining regulatory parameters with characterization methods, researchers can selectively fabricate collagenous biomaterials with various functional responses for biomedical applications.
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Affiliation(s)
- Shichen Zhu
- College of Food Science and Technology and MOE Key Laboratory of Environment Correlative Dietology
- Huazhong Agricultural University
- Wuhan 430070
- P. R. China
- Collaborative Innovation Center for Efficient and Health Production of Fisheries in Hunan Province
| | - Qijuan Yuan
- Guangdong Provincial Key Laboratory of Sensor Technology and Biomedical Instrument
- School of Engineering
- Sun Yat-sen University
- Guangzhou 510006
- P. R. China
| | - Tao Yin
- College of Food Science and Technology and MOE Key Laboratory of Environment Correlative Dietology
- Huazhong Agricultural University
- Wuhan 430070
- P. R. China
| | - Juan You
- College of Food Science and Technology and MOE Key Laboratory of Environment Correlative Dietology
- Huazhong Agricultural University
- Wuhan 430070
- P. R. China
| | - Zhipeng Gu
- Guangdong Provincial Key Laboratory of Sensor Technology and Biomedical Instrument
- School of Engineering
- Sun Yat-sen University
- Guangzhou 510006
- P. R. China
| | - Shanbai Xiong
- College of Food Science and Technology and MOE Key Laboratory of Environment Correlative Dietology
- Huazhong Agricultural University
- Wuhan 430070
- P. R. China
- Collaborative Innovation Center for Efficient and Health Production of Fisheries in Hunan Province
| | - Yang Hu
- College of Food Science and Technology and MOE Key Laboratory of Environment Correlative Dietology
- Huazhong Agricultural University
- Wuhan 430070
- P. R. China
- Collaborative Innovation Center for Efficient and Health Production of Fisheries in Hunan Province
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30
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Kennedy KM, Bhaw-Luximon A, Jhurry D. Cell-matrix mechanical interaction in electrospun polymeric scaffolds for tissue engineering: Implications for scaffold design and performance. Acta Biomater 2017; 50:41-55. [PMID: 28011142 DOI: 10.1016/j.actbio.2016.12.034] [Citation(s) in RCA: 115] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 11/10/2016] [Accepted: 12/15/2016] [Indexed: 12/24/2022]
Abstract
Engineered scaffolds produced by electrospinning of biodegradable polymers offer a 3D, nanofibrous environment with controllable structural, chemical, and mechanical properties that mimic the extracellular matrix of native tissues and have shown promise for a number of tissue engineering applications. The microscale mechanical interactions between cells and electrospun matrices drive cell behaviors including migration and differentiation that are critical to promote tissue regeneration. Recent developments in understanding these mechanical interactions in electrospun environments are reviewed, with emphasis on how fiber geometry and polymer structure impact on the local mechanical properties of scaffolds, how altering the micromechanics cues cell behaviors, and how, in turn, cellular and extrinsic forces exerted on the matrix mechanically remodel an electrospun scaffold throughout tissue development. Techniques used to measure and visualize these mechanical interactions are described. We provide a critical outlook on technological gaps that must be overcome to advance the ability to design, assess, and manipulate the mechanical environment in electrospun scaffolds toward constructs that may be successfully applied in tissue engineering and regenerative medicine. STATEMENT OF SIGNIFICANCE Tissue engineering requires design of scaffolds that interact with cells to promote tissue development. Electrospinning is a promising technique for fabricating fibrous, biomimetic scaffolds. Effects of electrospun matrix microstructure and biochemical properties on cell behavior have been extensively reviewed previously; here, we consider cell-matrix interaction from a mechanical perspective. Micromechanical properties as a driver of cell behavior has been well established in planar substrates, but more recently, many studies have provided new insights into mechanical interaction in fibrillar, electrospun environments. This review provides readers with an overview of how electrospun scaffold mechanics and cell behavior work in a dynamic feedback loop to drive tissue development, and discusses opportunities for improved design of mechanical environments that are conducive to tissue development.
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Uhlig MR, Magerle R. Unraveling capillary interaction and viscoelastic response in atomic force microscopy of hydrated collagen fibrils. NANOSCALE 2017; 9:1244-1256. [PMID: 28054696 DOI: 10.1039/c6nr07697a] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The mechanical properties of collagen fibrils depend on the amount and the distribution of water molecules within the fibrils. Here, we use atomic force microscopy (AFM) to study the effect of hydration on the viscoelastic properties of reconstituted type I collagen fibrils in air with controlled relative humidity. With the same AFM tip, we investigate the same area of a collagen fibril with two different force spectroscopy methods: force-distance (FD) and amplitude-phase-distance (APD) measurements. This allows us to separate the contributions of the fibril's viscoelastic response and the capillary force to the tip-sample interaction. A water bridge forms between the tip apex and the surface, causing an attractive capillary force, which is the main contribution to the energy dissipated from the tip to the specimen in dynamic AFM. The force hysteresis in the FD measurements and the tip indentation of only 2 nm in the APD measurements show that the hydrated collagen fibril is a viscoelastic solid. The mechanical properties of the gap regions and the overlap regions in the fibril's D-band pattern differ only in the top 2 nm but not in the fibril's bulk. We attribute this to the reduced number of intermolecular crosslinks in the reconstituted collagen fibril. The presented methodology allows the mechanical surface properties of hydrated collagenous tissues and biomaterials to be studied with unprecedented detail on the nanometer scale.
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Affiliation(s)
- Manuel R Uhlig
- Fakultät für Naturwissenschaften, Technische Universität Chemnitz, D-09107 Chemnitz, Germany.
| | - Robert Magerle
- Fakultät für Naturwissenschaften, Technische Universität Chemnitz, D-09107 Chemnitz, Germany.
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Lang G, Neugirg BR, Kluge D, Fery A, Scheibel T. Mechanical Testing of Engineered Spider Silk Filaments Provides Insights into Molecular Features on a Mesoscale. ACS APPLIED MATERIALS & INTERFACES 2017; 9:892-900. [PMID: 27935285 DOI: 10.1021/acsami.6b13093] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Spider dragline silk shows the highest toughness in comparison to all other known natural or man-made fibers. Despite a broad experimental foundation concerning the macroscopic silk thread properties as well as a thorough simulation-based molecular understanding, the impact of the mesoscale building blocks, namely nano-/submicrometer-sized filaments, on the mechanical properties of the threads remains the missing link. Here, we illustrate the function of these mesoscaled building blocks using electrospun fibers made of a recombinant spider silk protein and show the impact of β-sheet content and fiber hydration on their mechanical performance. Specifically elucidating the interplay between β-sheet-cross-linking (fiber strength) and structural water (fiber extensibility), the results bridge the gap between the molecular and the macroscopic view on the mechanics of spider silk. It is demonstrated that the extensibility of the here used single (MaSp2-like) protein system is in good accordance with the simulated extensibilities published by other groups. Furthermore, sufficient hydration of the fibers is shown to be a prerequisite to obtain a toughness in the range of that of natural dragline silk. Preliminary studies on electrospun fibers of the MaSp2-based recombinant spider silk proteins used in this work have indicated their basic applicability in the technical field of filter systems as well as in regenerative medicine. The presented work provides a fundamental understanding of the mechanical performance of such fibers under different wetting conditions, a prerequisite to further specify their potential for such applications.
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Affiliation(s)
| | | | | | - Andreas Fery
- Leibniz-Institut für Polymerforschung Dresden e. V., Institute of Physical Chemistry and Polymer Physics , Dresden 01069, Germany
- Chair for Physical Chemistry of Polymeric Materials, Technical University Dresden , Dresden 01069, Germany
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Size-dependent bending modulus of nanotubes induced by the imperfect boundary conditions. Sci Rep 2016; 6:38974. [PMID: 27941866 PMCID: PMC5150422 DOI: 10.1038/srep38974] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 11/07/2016] [Indexed: 01/05/2023] Open
Abstract
The size-dependent bending modulus of nanotubes, which was widely observed in most existing three-point bending experiments [e.g., J. Phys. Chem. B 117, 4618–4625 (2013)], has been tacitly assumed to originate from the shear effect. In this paper, taking boron nitride nanotubes as an example, we directly measured the shear effect by molecular dynamics (MD) simulations and found that the shear effect is not the major factor responsible for the observed size-dependent bending modulus of nanotubes. To further explain the size-dependence phenomenon, we abandoned the assumption of perfect boundary conditions (BCs) utilized in the aforementioned experiments and studied the influence of the BCs on the bending modulus of nanotubes based on MD simulations. The results show that the imperfect BCs also make the bending modulus of nanotubes size-dependent. Moreover, the size-dependence phenomenon induced by the imperfect BCs is much more significant than that induced by the shear effect, which suggests that the imperfect BC is a possible physical origin that leads to the strong size-dependence of the bending modulus found in the aforementioned experiments. To capture the physics behind the MD simulation results, a beam model with the general BCs is proposed and found to fit the experimental data very well.
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Šutka A, Antsov M, Järvekülg M, Visnapuu M, Heinmaa I, Mäeorg U, Vlassov S, Šutka A. Mechanical properties of individual fiber segments of electrospun lignocellulose-reinforced poly(vinyl alcohol). J Appl Polym Sci 2016. [DOI: 10.1002/app.44361] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Anna Šutka
- Institute of Design Technology, Riga Technical University; Kipsalas 6 Riga LV-1048 Latvia
- Laboratory of Biomass Eco-Efficient Conversion; Latvian State Institute of Wood Chemistry; Dzerbenes 27 Riga LV-1006 Latvia
| | - Mikk Antsov
- Institute of Physics, University of Tartu; Ravila 14c Tartu 50411 Estonia
| | - Martin Järvekülg
- Institute of Physics, University of Tartu; Ravila 14c Tartu 50411 Estonia
- Biomaterials Research Laboratory; Riga Technical University; Paula Valdena 3/7 Riga LV-1048 Latvia
| | - Meeri Visnapuu
- Institute of Physics, University of Tartu; Ravila 14c Tartu 50411 Estonia
| | - Ivo Heinmaa
- National Institute of Chemical Physics and Biophysics; Akadeemia Tee 23 Tallinn 12618 Estonia
| | - Uno Mäeorg
- Institute of Chemistry, University of Tartu; Ravila 14a Tartu 50411 Estonia
| | - Sergei Vlassov
- Institute of Physics, University of Tartu; Ravila 14c Tartu 50411 Estonia
| | - Andris Šutka
- Institute of Physics, University of Tartu; Ravila 14c Tartu 50411 Estonia
- Institute of Silicate Materials, Riga Technical University; Azenes 14/24 Riga LV-1048 Latvia
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Nanoscale studies link amyloid maturity with polyglutamine diseases onset. Sci Rep 2016; 6:31155. [PMID: 27499269 PMCID: PMC4976327 DOI: 10.1038/srep31155] [Citation(s) in RCA: 106] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 07/01/2016] [Indexed: 02/06/2023] Open
Abstract
The presence of expanded poly-glutamine (polyQ) repeats in proteins is directly linked to the pathogenesis of several neurodegenerative diseases, including Huntington’s disease. However, the molecular and structural basis underlying the increased toxicity of aggregates formed by proteins containing expanded polyQ repeats remain poorly understood, in part due to the size and morphological heterogeneity of the aggregates they form in vitro. To address this knowledge gap and technical limitations, we investigated the structural, mechanical and morphological properties of fibrillar aggregates at the single molecule and nanometer scale using the first exon of the Huntingtin protein as a model system (Exon1). Our findings demonstrate a direct correlation of the morphological and mechanical properties of Exon1 aggregates with their structural organization at the single aggregate and nanometric scale and provide novel insights into the molecular and structural basis of Huntingtin Exon1 aggregation and toxicity.
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