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Tang C, Han Z, Liu Z, Li W, Shen J, Zhang K, Mai S, Li J, Sun X, Chen X, Li H, Wang L, Liang J, Liao M, Feng J, Wang C, Wang J, Ye L, Yang Y, Xie S, Shi X, Zeng K, Zhang X, Cheng X, Zhang K, Guo Y, Yang H, Xu Y, Tong Q, Yu H, Chen P, Peng H, Sun X. A Soft-Fiber Bioelectronic Device with Axon-Like Architecture Enables Reliable Neural Recording In Vivo under Vigorous Activities. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024:e2407874. [PMID: 39054698 DOI: 10.1002/adma.202407874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2024] [Revised: 07/15/2024] [Indexed: 07/27/2024]
Abstract
Implantable neural devices that record neurons in various states, including static states, light activities such as walking, and vigorous activities such as running, offer opportunities for understanding brain functions and dysfunctions. However, recording neurons under vigorous activities remains a long-standing challenge because it leads to intense brain deformation. Thus, three key requirements are needed simultaneously for neural devices, that is, low modulus, low specific interfacial impedance, and high electrical conductivity, to realize stable device/brain interfaces and high-quality transmission of neural signals. However, they always contradict each other in current material strategies. Here, a soft fiber neural device capable of stably tracking individual neurons in the deep brain of medium-sized animals under vigorous activity is reported. Inspired by the axon architecture, this fiber neural device is constructed with a conductive gel fiber possessing a network-in-liquid structure using conjugated polymers and liquid matrices and then insulated with soft fluorine rubber. This strategy reconciles the contradictions and simultaneously confers the fiber neural device with low modulus (300 kPa), low specific impedance (579 kΩ µm2), and high electrical conductivity (32 700 S m-1) - ≈1-3 times higher than hydrogels. Stable single-unit spike tracking in running cats, which promises new opportunities for neuroscience is demonstrated.
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Affiliation(s)
- Chengqiang Tang
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Institute of Fiber Materials and Devices, and Laboratory of Advanced Materials, Fudan University, Shanghai, 200438, China
| | - Zhengqi Han
- Vision Research Laboratory, School of Life Sciences, State Key Laboratory of Medical Neurobiology, and Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, 200438, China
| | - Ziwei Liu
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Institute of Fiber Materials and Devices, and Laboratory of Advanced Materials, Fudan University, Shanghai, 200438, China
| | - Wenjun Li
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Institute of Fiber Materials and Devices, and Laboratory of Advanced Materials, Fudan University, Shanghai, 200438, China
| | - Jiahao Shen
- Department of Aeronautics and Astronautics, Fudan University, Shanghai, 200433, China
| | - Kailin Zhang
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Institute of Fiber Materials and Devices, and Laboratory of Advanced Materials, Fudan University, Shanghai, 200438, China
| | - Shuting Mai
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Institute of Fiber Materials and Devices, and Laboratory of Advanced Materials, Fudan University, Shanghai, 200438, China
| | - Jinyan Li
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Institute of Fiber Materials and Devices, and Laboratory of Advanced Materials, Fudan University, Shanghai, 200438, China
| | - Xiao Sun
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Institute of Fiber Materials and Devices, and Laboratory of Advanced Materials, Fudan University, Shanghai, 200438, China
| | - Xingfei Chen
- Vision Research Laboratory, School of Life Sciences, State Key Laboratory of Medical Neurobiology, and Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, 200438, China
| | - Hongjian Li
- Vision Research Laboratory, School of Life Sciences, State Key Laboratory of Medical Neurobiology, and Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, 200438, China
| | - Liyuan Wang
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Institute of Fiber Materials and Devices, and Laboratory of Advanced Materials, Fudan University, Shanghai, 200438, China
| | - Jiaheng Liang
- Vision Research Laboratory, School of Life Sciences, State Key Laboratory of Medical Neurobiology, and Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, 200438, China
| | - Meng Liao
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Institute of Fiber Materials and Devices, and Laboratory of Advanced Materials, Fudan University, Shanghai, 200438, China
| | - Jianyou Feng
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Institute of Fiber Materials and Devices, and Laboratory of Advanced Materials, Fudan University, Shanghai, 200438, China
| | - Chuang Wang
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Institute of Fiber Materials and Devices, and Laboratory of Advanced Materials, Fudan University, Shanghai, 200438, China
| | - Jiajia Wang
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Institute of Fiber Materials and Devices, and Laboratory of Advanced Materials, Fudan University, Shanghai, 200438, China
| | - Lei Ye
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Institute of Fiber Materials and Devices, and Laboratory of Advanced Materials, Fudan University, Shanghai, 200438, China
| | - Yiqing Yang
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Institute of Fiber Materials and Devices, and Laboratory of Advanced Materials, Fudan University, Shanghai, 200438, China
| | - Songlin Xie
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Institute of Fiber Materials and Devices, and Laboratory of Advanced Materials, Fudan University, Shanghai, 200438, China
| | - Xiang Shi
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Institute of Fiber Materials and Devices, and Laboratory of Advanced Materials, Fudan University, Shanghai, 200438, China
| | - Kaiwen Zeng
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Institute of Fiber Materials and Devices, and Laboratory of Advanced Materials, Fudan University, Shanghai, 200438, China
| | - Xuefeng Zhang
- School of Life Sciences, Fudan University, Shanghai, 200433, China
| | - Xiangran Cheng
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Institute of Fiber Materials and Devices, and Laboratory of Advanced Materials, Fudan University, Shanghai, 200438, China
| | - Kun Zhang
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Institute of Fiber Materials and Devices, and Laboratory of Advanced Materials, Fudan University, Shanghai, 200438, China
| | - Yue Guo
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Institute of Fiber Materials and Devices, and Laboratory of Advanced Materials, Fudan University, Shanghai, 200438, China
| | - Han Yang
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Institute of Fiber Materials and Devices, and Laboratory of Advanced Materials, Fudan University, Shanghai, 200438, China
| | - Yifei Xu
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Institute of Fiber Materials and Devices, and Laboratory of Advanced Materials, Fudan University, Shanghai, 200438, China
| | - Qi Tong
- Department of Aeronautics and Astronautics, Fudan University, Shanghai, 200433, China
| | - Hongbo Yu
- Vision Research Laboratory, School of Life Sciences, State Key Laboratory of Medical Neurobiology, and Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, 200438, China
| | - Peining Chen
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Institute of Fiber Materials and Devices, and Laboratory of Advanced Materials, Fudan University, Shanghai, 200438, China
| | - Huisheng Peng
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Institute of Fiber Materials and Devices, and Laboratory of Advanced Materials, Fudan University, Shanghai, 200438, China
| | - Xuemei Sun
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Institute of Fiber Materials and Devices, and Laboratory of Advanced Materials, Fudan University, Shanghai, 200438, China
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2
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Ananthasubramanian P, Sahay R, Raghavan N. Investigation of the surface mechanical properties of functionalized single-walled carbon nanotube (SWCNT) reinforced PDMS nanocomposites using nanoindentation analysis. RSC Adv 2024; 14:15249-15260. [PMID: 38737970 PMCID: PMC11082875 DOI: 10.1039/d4ra02717e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2024] [Accepted: 04/23/2024] [Indexed: 05/14/2024] Open
Abstract
Functionalizing single-walled carbon nanotubes (SWCNT) with different chemical functional groups directly enhances their chemical adhesion and dispersion in viscous polymeric resins such as polydimethylsiloxane (PDMS). Nevertheless, the ideal surface polarity (hydrophilic or hydrophobic) for SWCNT to foster stronger chemical bonding with PDMS remains uncertain. This investigation delves into the impact of enhanced SWCNT dispersion within PDMS on the surface mechanical characteristics of this flexible composite system. We use carboxylic acid-functionalized SWCNT (COOH-SWCNT) and silane-functionalized SWCNT (sily-SWCNT), recognized for their hydrophilic and hydrophobic surface polarities, respectively, as reinforcing agents at ultra-low weight percentage loadings: 0.05 wt%, 0.5 wt%, and 1 wt%. We perform quasi-static nanoindentation analysis employing a Berkovich tip to probe the localized mechanical behavior of PDMS-SWCNT films at an indentation depth of 1 μm. Plastic deformation within the samples, denoted as plastic work (Wp), as well as the elastic modulus (E), hardness (H), and contact stiffness (Sc) of the composites are examined from the force-displacement curves to elucidate the enhancement in the surface mechanical attributes of the composite films.
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Affiliation(s)
- Pavithra Ananthasubramanian
- nano-Macro Reliability Laboratory, Engineering Product Development Pillar, Singapore University of Technology and Design 8 Somapah Road Singapore 487372
| | - Rahul Sahay
- nano-Macro Reliability Laboratory, Engineering Product Development Pillar, Singapore University of Technology and Design 8 Somapah Road Singapore 487372
| | - Nagarajan Raghavan
- nano-Macro Reliability Laboratory, Engineering Product Development Pillar, Singapore University of Technology and Design 8 Somapah Road Singapore 487372
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3
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Davis S, Karali A, Balcaen T, Zekonyte J, Pétré M, Roldo M, Kerckhofs G, Blunn G. Comparison of two contrast-enhancing staining agents for use in X-ray imaging and digital volume correlation measurements across the cartilage-bone interface. J Mech Behav Biomed Mater 2024; 152:106414. [PMID: 38277908 DOI: 10.1016/j.jmbbm.2024.106414] [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: 03/08/2023] [Revised: 12/11/2023] [Accepted: 01/19/2024] [Indexed: 01/28/2024]
Abstract
OBJECTIVE The pathogenesis of osteoarthritis (OA) is associated with subchondral bone changes, which is linked to abnormal strain distribution in the overlying articular cartilage. This highlights the importance of understanding mechanical interaction at the cartilage-bone interface. The aim of this study is to compare solutions of two contrast-enhancing staining agents (CESA) for combining high-resolution Contrast-Enhanced X-ray microfocus Computed Tomography (CECT) with Digital Volume Correlation (DVC) for full-field strain measurements at the cartilage-bone interface. DESIGN Bovine osteochondral plugs were stained with phosphotungstic acid (PTA) in 70% ethanol or 1:2 hafnium-substituted Wells-Dawson polyoxometalate (Hf-WD POM) in PBS. Mechanical properties were assessed using micromechanical probing and nanoindentation. Strain uncertainties (from CECT data) were evaluated following two consecutive unloaded scans. Residual strains were computed following unconfined compression (ex situ) testing. RESULTS PTA and Hf-WD POM enabled the visualisation of structural features in cartilage, allowing DVC computation on the CECT data. Residual strains up to ∼10,000 μɛ were detected up to the tidemark. Nanoindentation showed that PTA-staining caused an average ∼6-fold increase in articular cartilage stiffness, a ∼19-fold increase in reduced modulus and ∼7-fold increase in hardness, whereas Hf-WD POM-stained specimens had mechanical properties similar to pre-stain tissue. Micromechanical probing showed a 77% increase in cartilage surface stiffness after PTA-staining, in comparison to a 16% increase in stiffness after staining with Hf-WD POM. CONCLUSION Hf-WD POM is a more suitable CESA solution compared to PTA for CECT imaging combined with DVC as it allowed visualisation of structural features in the cartilage tissue whilst more closely maintaining tissue mechanical properties.
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Affiliation(s)
- Sarah Davis
- School of Pharmacy and Biomedical Science, University of Portsmouth, Portsmouth, PO1 2DT, UK; School of Mechanical and Design Engineering, University of Portsmouth, PO1 3DJ, UK.
| | - Aikaterina Karali
- School of Mechanical and Design Engineering, University of Portsmouth, PO1 3DJ, UK
| | - Tim Balcaen
- Biomechanics Lab, Institute of Mechanics, Materials and Civil Engineering, UCLouvain, Louvain-la-Neuve, Belgium; Pole of Morphology, Institute of Experimental and Clinical Research, UCLouvain, Brussels, Belgium; Molecular Design and Synthesis, Department of Chemistry, KU Leuven, Leuven, Belgium
| | - Jurgita Zekonyte
- School of Mechanical and Design Engineering, University of Portsmouth, PO1 3DJ, UK
| | - Maïté Pétré
- Biomechanics Lab, Institute of Mechanics, Materials and Civil Engineering, UCLouvain, Louvain-la-Neuve, Belgium; Pole of Morphology, Institute of Experimental and Clinical Research, UCLouvain, Brussels, Belgium; Biomechanics Section, Department of Mechanical Engineering, KU Leuven, Heverlee, Belgium
| | - Marta Roldo
- School of Pharmacy and Biomedical Science, University of Portsmouth, Portsmouth, PO1 2DT, UK
| | - Greet Kerckhofs
- Biomechanics Lab, Institute of Mechanics, Materials and Civil Engineering, UCLouvain, Louvain-la-Neuve, Belgium; Pole of Morphology, Institute of Experimental and Clinical Research, UCLouvain, Brussels, Belgium; Department of Materials Engineering, KU Leuven, Heverlee, Belgium; Prometheus, Division for Skeletal Tissue Engineering, KU Leuven, Leuven, Belgium
| | - Gordon Blunn
- School of Pharmacy and Biomedical Science, University of Portsmouth, Portsmouth, PO1 2DT, UK
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4
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Yuan X, Wang Z, Feng F, Bu Y, Fan Z, Liu H, Li P, Zhang L, Li X, Hu Z. Measurement of pressure discomfort threshold in auricular concha for in-ear wearables design. APPLIED ERGONOMICS 2023; 113:104078. [PMID: 37385130 DOI: 10.1016/j.apergo.2023.104078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 05/14/2023] [Accepted: 06/20/2023] [Indexed: 07/01/2023]
Abstract
In an effort to mitigate the homogenization of in-ear wearables, designers have been focusing on finding new solutions to enhance user comfort. While the concept of pressure discomfort thresholds (PDT) in humans has been applied to product design, research on the auricular concha remains scarce. In this study, we conducted an experiment to measure the PDT at six points in the auricular concha of 80 participants. Our results showed that the tragus was the most sensitive area and that gender, symmetry, and Body Mass Index (BMI)had no significant effect on PDT. Based on these findings, we generated pressure sensitivity maps of the auricular concha to aid in the optimization of in-ear wearable design.
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Affiliation(s)
- Xinyi Yuan
- School of Mechanical Engineering, Shandong University, Jinan, China
| | - Zijian Wang
- School of Mechanical Engineering, Shandong University, Jinan, China
| | - Feng Feng
- Computer Science Department, Aalto University, Finland
| | - Yuanyuan Bu
- School of Mechanical Engineering, Shandong University, Jinan, China
| | - Zhijun Fan
- School of Mechanical Engineering, Shandong University, Jinan, China.
| | - Heshan Liu
- School of Mechanical Engineering, Shandong University, Jinan, China
| | - Puhong Li
- School of Arts and Design, Qilu University of Technology (Shandong Academy of Sciences), Jinan, China
| | - Luan Zhang
- Goertek Institute of Technology, Goertek Inc., Qingdao, China
| | - Xiao Li
- Goertek Institute of Technology, Goertek Inc., Qingdao, China
| | - Zhiwei Hu
- Goertek Institute of Technology, Goertek Inc., Qingdao, China
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5
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Davis S, Zekonyte J, Karali A, Roldo M, Blunn G. Early Degenerative Changes in a Spontaneous Osteoarthritis Model Assessed by Nanoindentation. Bioengineering (Basel) 2023; 10:995. [PMID: 37760097 PMCID: PMC10525236 DOI: 10.3390/bioengineering10090995] [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: 07/26/2023] [Revised: 08/15/2023] [Accepted: 08/18/2023] [Indexed: 09/29/2023] Open
Abstract
Understanding early mechanical changes in articular cartilage (AC) and subchondral bone (SB) is crucial for improved treatment of osteoarthritis (OA). The aim of this study was to develop a method for nanoindentation of fresh, unfixed osteochondral tissue to assess the early changes in the mechanical properties of AC and SB. Nanoindentation was performed throughout the depth of AC and SB in the proximal tibia of Dunkin Hartley guinea pigs at 2 months, 3 months, and 2 years of age. The contralateral tibias were either histologically graded for OA or analyzed using immunohistochemistry. The results showed an increase in the reduced modulus (Er) in the deep zone of AC during early-stage OA (6.0 ± 1.75 MPa) compared to values at 2 months (4.04 ± 1.25 MPa) (*** p < 0.001). In severe OA (2-year) specimens, there was a significant reduction in Er throughout the superficial and middle AC zones, which correlated to increased ADAMTS 4 and 5 staining, and proteoglycan loss in these regions. In the subchondral bone, a 35.0% reduction in stiffness was observed between 2-month and 3-month specimens (*** p < 0.001). The severe OA age group had significantly increased SB stiffness of 36.2% and 109.6% compared to 2-month and 3-month-old specimens respectively (*** p < 0.001). In conclusion, this study provides useful information about the changes in the mechanical properties of both AC and SB during both early- and late-stage OA and indicates that an initial reduction in stiffness of the SB and an increase in stiffness in the deep zone of AC may precede early-stage cartilage degeneration.
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Affiliation(s)
- Sarah Davis
- School of Pharmacy and Biomedical Science, University of Portsmouth, Portsmouth PO1 2DT, UK; (M.R.); (G.B.)
- School of Mechanical and Design Engineering, University of Portsmouth, Portsmouth PO1 3DJ, UK; (J.Z.); (A.K.)
| | - Jurgita Zekonyte
- School of Mechanical and Design Engineering, University of Portsmouth, Portsmouth PO1 3DJ, UK; (J.Z.); (A.K.)
| | - Aikaterina Karali
- School of Mechanical and Design Engineering, University of Portsmouth, Portsmouth PO1 3DJ, UK; (J.Z.); (A.K.)
| | - Marta Roldo
- School of Pharmacy and Biomedical Science, University of Portsmouth, Portsmouth PO1 2DT, UK; (M.R.); (G.B.)
| | - Gordon Blunn
- School of Pharmacy and Biomedical Science, University of Portsmouth, Portsmouth PO1 2DT, UK; (M.R.); (G.B.)
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Masson AO, Besler B, Edwards WB, Krawetz RJ. High spatial resolution analysis using automated indentation mapping differentiates biomechanical properties of normal vs. degenerated articular cartilage in mice. eLife 2022; 11:74664. [PMID: 36444976 DOI: 10.7554/elife.74664] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Accepted: 11/28/2022] [Indexed: 11/30/2022] Open
Abstract
Characterizing the biomechanical properties of articular cartilage is crucial to understanding processes of tissue homeostasis vs. degeneration. In mouse models, however, limitations are imposed by their small joint size and thin cartilage surfaces. Here we present a three-dimensional (3D) automated surface mapping system and methodology that allows for mechanical characterization of mouse cartilage with high spatial resolution. We performed repeated indentation mappings, followed by cartilage thickness measurement via needle probing, at 31 predefined positions distributed over the medial and lateral femoral condyles of healthy mice. High-resolution 3D x-ray microscopy (XRM) imaging was used to validate tissue thickness measurements. The automated indentation mapping was reproducible, and needle probing yielded cartilage thicknesses comparable to XRM imaging. When comparing healthy vs. degenerated cartilage, topographical variations in biomechanics were identified, with altered thickness and stiffness (instantaneous modulus) across condyles and within anteroposterior sub-regions. This quantitative technique comprehensively characterized cartilage function in mice femoral condyle cartilage. Hence, it has the potential to improve our understanding of tissue structure-function interplay in mouse models of repair and disease.
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Affiliation(s)
- Anand O Masson
- Biomedical Engineering Graduate Program, University of Calgary, Calgary, Canada.,McCaig Institute for Bone and Joint Health, University of Calgary, Calgary, Canada
| | - Bryce Besler
- Biomedical Engineering Graduate Program, University of Calgary, Calgary, Canada.,McCaig Institute for Bone and Joint Health, University of Calgary, Calgary, Canada
| | - W Brent Edwards
- Biomedical Engineering Graduate Program, University of Calgary, Calgary, Canada.,McCaig Institute for Bone and Joint Health, University of Calgary, Calgary, Canada.,Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Canada
| | - Roman J Krawetz
- Biomedical Engineering Graduate Program, University of Calgary, Calgary, Canada.,McCaig Institute for Bone and Joint Health, University of Calgary, Calgary, Canada.,Department of Surgery, Cumming School of Medicine, University of Calgary, Calgary, Canada.,Department of Cell Biology and Anatomy, Cumming School of Medicine, University of Calgary, Calgary, Canada
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Berni M, Erani P, Lopomo NF, Baleani M. Optimization of In Situ Indentation Protocol to Map the Mechanical Properties of Articular Cartilage. MATERIALS (BASEL, SWITZERLAND) 2022; 15:6425. [PMID: 36143736 PMCID: PMC9505484 DOI: 10.3390/ma15186425] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Revised: 08/29/2022] [Accepted: 09/13/2022] [Indexed: 06/16/2023]
Abstract
Tissue engineering aims at developing complex composite scaffolds for articular cartilage repair. These scaffolds must exhibit a mechanical behavior similar to the whole osteochondral unit. In situ spherical indentation allows us to map the mechanical behavior of articular cartilage, avoiding removal of the underlying bone tissue. Little is known about the impact of grid spacing, indenter diameter, and induced deformation on the cartilage response to indentation. We investigated the impact of grid spacing (range: a to 3a, where a is the radius of the contact area between cartilage and indenter), indenter diameter (range: 1 to 8 mm), and deformation induced by indentation (constant indentation depth versus constant nominal deformation) on cartilage response. The bias induced by indentations performed in adjacent grid points was minimized with a 3a grid spacing. The cartilage response was indenter-dependent for diameters ranging between 1 and 6 mm with a nominal deformation of 15%. No significant differences were found using 6 mm and 8 mm indenters. Six mm and 8 mm indenters were used to map human articular cartilage with a grid spacing equal to 3a. Instantaneous elastic modulus E0 was calculated for constant indentation depth and constant nominal deformation. E0 value distribution did not change significantly by switching the two indenters, while dispersion decreased by 5-6% when a constant nominal deformation was applied. Such an approach was able to discriminate changes in tissue response due to doubling the indentation rate. The proposed procedure seems to reduce data dispersion and properly determine cartilage mechanical properties to be compared with those of complex composite scaffolds.
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Affiliation(s)
- Matteo Berni
- Laboratorio di Tecnologia Medica, IRCCS Istituto Ortopedico Rizzoli, 40136 Bologna, Italy
| | - Paolo Erani
- Laboratorio di Tecnologia Medica, IRCCS Istituto Ortopedico Rizzoli, 40136 Bologna, Italy
| | | | - Massimiliano Baleani
- Laboratorio di Tecnologia Medica, IRCCS Istituto Ortopedico Rizzoli, 40136 Bologna, Italy
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8
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Arevalo SE, Ebenstein DM, Pruitt LA. A methodological framework for nanomechanical characterization of soft biomaterials and polymers. J Mech Behav Biomed Mater 2022; 134:105384. [DOI: 10.1016/j.jmbbm.2022.105384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 07/08/2022] [Accepted: 07/15/2022] [Indexed: 11/24/2022]
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9
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Jin C, Zhu R, Xu ML, Zheng LD, Zeng HZ, Xie N, Cheng LM. Effect of Velocity and Contact Stress Area on the Dynamic Behavior of the Spinal Cord Under Different Testing Conditions. Front Bioeng Biotechnol 2022; 10:762555. [PMID: 35309983 PMCID: PMC8931460 DOI: 10.3389/fbioe.2022.762555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Accepted: 01/31/2022] [Indexed: 11/28/2022] Open
Abstract
Knowledge of the dynamic behavior of the spinal cord under different testing conditions is critical for our understanding of biomechanical mechanisms of spinal cord injury. Although velocity and contact stress area are known to affect external mechanical stress or energy upon sudden traumatic injury, quantitative investigation of the two clinically relevant biomechanical variables is limited. Here, freshly excised rat spinal-cord–pia-arachnoid constructs were tested through indentation using indenters of different sizes (radii: 0.25, 0.50, and 1.00 mm) at various loading rates ranging from 0.04 to 0.20 mm/s. This analysis found that the ex vivo specimen displayed significant nonlinear viscoelasticity at <10% of specimen thickness depth magnitudes. At higher velocity and larger contact stress area, the cord withstood a higher peak load and exhibited more sensitive mechanical relaxation responses (i.e., increasing amplitude and speed of the drop in peak load). Additionally, the cord became stiffer (i.e., increasing elastic modulus) and softer (i.e., decreasing elastic modulus) at a higher velocity and larger contact stress area, respectively. These findings will improve our understanding of the real-time complex biomechanics involved in traumatic spinal cord injury.
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Affiliation(s)
| | | | | | | | | | - Ning Xie
- *Correspondence: Ning Xie, ; Li-ming Cheng,
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10
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Shah P, Luximon Y. Assessment of pressure sensitivity in the head region for Chinese adults. APPLIED ERGONOMICS 2021; 97:103548. [PMID: 34391990 DOI: 10.1016/j.apergo.2021.103548] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 07/04/2021] [Accepted: 08/01/2021] [Indexed: 06/13/2023]
Abstract
Measurement of pressure threshold has found its applications in the fields of medical sciences and product design. Hence it has been a profound area of research interest for several decades. However, hardly any detailed investigation has been undertaken to measure the pressure threshold in the head region. In this study, Pressure Discomfort Threshold (PDT) and Pressure Pain Threshold (PPT) were measured for two hundred eighteen healthy Chinese adults at seventy-six anatomical locations, and further statistical analyses were performed on the acquired data to understand the relationship between different demographic parameters. The results suggest that the pressure sensitivity is low in the vertex region, moderate in the forehead and temporal area, and high in the facial and nasal region. From this study, pressure sensitivity maps were developed for PDT and PPT for Chinese adults. The measured pressure threshold data showed no significant relationship with age and Body Mass Index (BMI).
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Affiliation(s)
- Parth Shah
- School of Design, The Hong Kong Polytechnic University, Hong Kong Special Administrative Region
| | - Yan Luximon
- School of Design, The Hong Kong Polytechnic University, Hong Kong Special Administrative Region.
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11
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Huang Y, Wang J, Yu WJ, Yu Y, Li RY, Gao Q, Ren KF, Ji J. A Bioinspired Hydrogel-Elastomer Hybrid Surface for Enhanced Mechanical Properties and Lubrication. ACS APPLIED MATERIALS & INTERFACES 2021; 13:50461-50469. [PMID: 34641666 DOI: 10.1021/acsami.1c17345] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Developing surfaces that realize lubrication and durable wear resistance under high pressure has great implications in areas ranging from electromechanical systems to advanced biomedical devices but has proven challenging. Inspired by the zonal and transitional structure of articular cartilage, we fabricate a hydrogel-elastomer hybrid surface, where the hydrogel interpenetrates into the polymer elastomer substrate as a transitional and bonding zone, that exhibits a low coefficient of friction and wear resistance under a high load. First, we entrap benzophenone within the surface of polymer substrates such as polydimethylsiloxane, polyvinylchloride, and polyurethane. The hybrid surface is then achieved through initiating polymerization of the acrylamide monomer on the polymer surface upon ultraviolet irradiation. We observe an interpenetration area of the hydrogel and the polymer substrate. The hybrid surface shows a low coefficient of friction (∼0.05) under a very high load (over 100 atm contact pressure). It conserves the lubrication property over 100,000 cycles under a 10.9 MPa pressure and shows slight wear. This work brings a new perspective on designing surfaces with a lubrication property and wear resistance, showing broad applications.
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Affiliation(s)
- Yan Huang
- MOE Key Laboratory of Macromolecule Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027, China
| | - Jing Wang
- MOE Key Laboratory of Macromolecule Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027, China
| | - Wei-Jiang Yu
- MOE Key Laboratory of Macromolecule Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027, China
| | - Yan Yu
- MOE Key Laboratory of Macromolecule Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027, China
| | - Ren-Yun Li
- MOE Key Laboratory of Macromolecule Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027, China
| | - Qiang Gao
- MOE Key Laboratory of Macromolecule Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027, China
| | - Ke-Feng Ren
- MOE Key Laboratory of Macromolecule Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027, China
| | - Jian Ji
- MOE Key Laboratory of Macromolecule Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027, China
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Effect of cross-linking and hydration on microscale flat punch indentation contact to collagen-hyaluronic acid films in the viscoelastic limit. Acta Biomater 2020; 111:279-289. [PMID: 32417264 DOI: 10.1016/j.actbio.2020.04.043] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2019] [Revised: 04/21/2020] [Accepted: 04/23/2020] [Indexed: 11/23/2022]
Abstract
The properties of the extracellular matrix (ECM) have profound impact upon cell behaviour. As an abundant protein in mammals, collagen is a desirable base material to engineer an ECM tissue scaffold, but its structural weakness generally requires molecular crosslinking or incorporation of additional ECM-based macromolecules such as glycosaminoglycans. We have performed microscopic indentation to test collagen films under dry and aqueous conditions prepared with different levels of physical and chemical crosslinking. Our technique isolates intrinsic properties of the poro-viscoelastic matrix in a regime minimizing the influence of drainage hydrodynamics and allows direct measurement of the effect of hydrating a specific sample. A doubling of the effective stress-strain stiffness under crosslinking could be directly correlated to structural changes in X-ray diffraction spectra, while electron microscopy revealed possible fibril bridging mechanisms explaining observed toughness. Overall, an intrinsic viscoelastic stress-strain response of collagen under various conditions of cross-linking was observed for both dry and wet conditions, with the latter most affected by indentation rate. Under creep testing, a three order of magnitude increase in dynamic compliance and factor three reduction in relaxation time was found going from the dry to hydrated state. When fitted to a simple viscoelastic model, crosslinking showed a tendency to decrease relaxation time in both states, but reduced dynamic compliance only in the hydrated case. This suggests a reduced role of virtual crosslinks under hydration. This is the first study reporting consistent mechanical testing of dry and hydrated ECM-derived biomaterials, accessing the intrinsic material mechanics under in vivo-like conditions. STATEMENT OF SIGNIFICANCE: This manuscript presents new insights into the effect of crosslinking on mechanical properties of dry and hydrated collagen intended for tissue scaffolding applications. A novel microscopic indentation technique allowed testing of the poro-viscoelastic matrix isolated in a regime minimizing the influence of drainage hydrodynamics, so direct comparison of the effect of hydration on the intrinsic material behaviour to could be made. A variety of experimental techniques including X-ray diffraction, infrared spectroscopy, and scanning electron and atomic force microscopy were used to augment the mechanical testing. The results of creep testing were numerically analysed using a four-component viscoelastic model. This is the first mechanical testing of dry and hydrated ECM-derived biomaterials, accessing the intrinsic material mechanics under in vivo-like conditions.
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Mistry D, Nikkhou M, Raistrick T, Hussain M, Jull EIL, Baker DL, Gleeson HF. Isotropic Liquid Crystal Elastomers as Exceptional Photoelastic Strain Sensors. Macromolecules 2020. [DOI: 10.1021/acs.macromol.9b02456] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- Devesh Mistry
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Maryam Nikkhou
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Thomas Raistrick
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Mariam Hussain
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Ethan I. L. Jull
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Daniel L. Baker
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Helen F. Gleeson
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, United Kingdom
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Lee H, Campbell WD, Theis KM, Canning ME, Ennis HY, Jackson RL, Hanson RR. Comparison Between the Hyperelastic Behavior of Fresh and Frozen Equine Articular Cartilage in Various Joints. J Biomech Eng 2020; 142:024501. [PMID: 31201742 PMCID: PMC7104741 DOI: 10.1115/1.4044031] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 05/29/2019] [Indexed: 11/08/2022]
Abstract
Fresh and frozen cartilage samples of the fetlock, carpus, and stifle were collected from 12 deceased horses. Half were measured immediately following extraction, and half were frozen for seven days and then measured. Seven indentations (various normalized displacements) were implemented with an indention rate of 0.1 mm/s. Solid phase aggregate modulus (Es), hyperelastic material constant (α), and fluid load fraction (F') of equine articular cartilage were assessed using the Ogden hyperelastic model. The properties were statistically compared in various joints (fetlock, carpus, and stifle), and between fresh and frozen samples using various statistical models. There was no statistical difference between the fetlock and carpus in the aggregate modulus (p = 0.5084), while both were significantly different from the stifle (fetlock: p = 0.0017 and carpus: p = 0.0406). For the hyperelastic material constant, no statistical differences between joints were observed (p = 0.3310). For the fluid load fraction, the fetlock and stifle comparison showed a difference (p = 0.0333), while the carpus was not different from the fetlock (p = 0.1563) or stifle (p = 0.3862). Comparison between the fresh and frozen articular cartilage demonstrated no significant difference among the joints in the three material properties: p = 0.9418, p = 0.7031, and p = 0.9313 for the aggregate modulus, the hyperelastic material constant, and the fluid load fraction, respectively.
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Affiliation(s)
- Hyeon Lee
- Department of Mechanical Engineering, Samuel Ginn College of
Engineering, Auburn University, Auburn, AL
36849; Department of Mechanical Engineering, Virginia
Tech, 460 Old Turner Street (MC 0710), 100S Randolph
Hall, Blacksburg, VA 24061
| | - William D. Campbell
- Department of Mechanical Engineering, Samuel Ginn College of
Engineering, Auburn University, Auburn, AL
36849
| | - Kelcie M. Theis
- Department of Clinical Sciences, College of Veterinary
Medicine, Auburn University, Auburn, AL
36849
| | - Margaret E. Canning
- Department of Clinical Sciences, College of Veterinary
Medicine, Auburn University, Auburn 36849,
AL
| | - Hannah Y. Ennis
- Department of Clinical Sciences, College of Veterinary
Medicine, Auburn University, Auburn 36849,
AL
| | - Robert L. Jackson
- Department of Mechanical Engineering, Samuel Ginn College of
Engineering, Auburn University, Auburn, AL
36849
| | - R. Reid Hanson
- Department of Clinical Sciences, College of Veterinary
Medicine, Auburn University, Auburn 36849,
AL
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Chandran PL, Dimitriadis EK, Mertz EL, Horkay F. Microscale mapping of extracellular matrix elasticity of mouse joint cartilage: an approach to extracting bulk elasticity of soft matter with surface roughness. SOFT MATTER 2018; 14:2879-2892. [PMID: 29582024 PMCID: PMC5922260 DOI: 10.1039/c7sm02045g] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Cartilage is composed of cells and an extracellular matrix, the latter being a composite of a collagen mesh interpenetrated by proteoglycans responsible for tissue osmotic swelling. The matrix composition and structure vary through the tissue depth. Mapping such variability requires tissue sectioning to gain access. The resulting surface roughness, and concomitant proteoglycan loss contribute to large uncertainties in elastic modulus estimates. To extract elasticity values for the bulk matrix which are not obfuscated by the indeterminate surface layer, we developed a novel experimental and data analysis methodology. We analyzed the surface roughness to optimize the probe size, and performed high-resolution (1 μm) elasticity mapping on thin (∼12 μm), epiphyseal newborn mouse cartilage sections cut parallel to the bone longitudinal axis or normal to the articular surface. Mild fixation prevented the major proteoglycan loss observed in unfixed specimens but not the stress release that resulted in thickness changes in the sectioned matrix. Our novel data analysis method introduces a virtual contact point as a fitting parameter for the Hertz model, to minimize the effects of surface roughness and corrects for the finite section thickness. Our estimates of cartilage elasticity converge with increasing indentation depth and, unlike previous data interpretations, are consistent with linearly elastic material. A high cell density that leaves narrow matrix septa between cells may cause the underestimation of elastic moduli, whereas fixation probably causes an overestimation. The proposed methodology has broader relevance to nano- and micro-indentation of soft materials with multiple length scales of organization and whenever surface effects (including roughness, electrostatics, van der Waals forces, etc.) become significant.
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Mittelstaedt D, Kahn D, Xia Y. Detection of early osteoarthritis in canine knee joints 3 weeks post ACL transection by microscopic MRI and biomechanical measurement. J Orthop Surg (Hong Kong) 2018; 26:2309499018778357. [PMID: 29871538 PMCID: PMC6388617 DOI: 10.1177/2309499018778357] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
PURPOSE To detect early osteoarthritis (OA) in a canine Pond-Nuki model 3 weeks after anterior cruciate ligament (ACL) transection surgery, both topographically over the medial tibial surface and depth-dependently over the cartilage thickness. METHODS Four topographical locations on each OA and contralateral medial tibia were imaged individually by magnetic resonance imaging (MRI) at 17.6 µm transverse resolution. The quantitative MRI T2 relaxation data were correlated with the biomechanical stress-relaxation measurements from adjacent locations. RESULTS OA cartilage was thinner than the contralateral tissue and had a lower modulus compared to the contralateral cartilage for the exterior, interior, and central medial tibia locations. Depth-dependent and topographical variations were detected in OA cartilage by a number of parameters (compressive modulus, glycosaminoglycan concentration, bulk and zonal thicknesses, T2 at 0° and 55° specimen orientations in the magnet). T2 demonstrated significant differences at varying depths between OA and contralateral cartilage. CONCLUSION ACL transection caused a number of changes in the tibial cartilage at 3 weeks after the surgery. The characteristics of these changes, which are topographic and depth-dependent, likely reflect the complex degradation in this canine model of OA at the early developmental stage.
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Affiliation(s)
- Daniel Mittelstaedt
- Department of Physics, Center for Biomedical Research, Oakland University, Rochester, MI, USA
| | - David Kahn
- Department of Physics, Center for Biomedical Research, Oakland University, Rochester, MI, USA,Stony Brook University Hospital, Department of Radiation Oncology, Stony Brook, NY 11794, USA
| | - Yang Xia
- Department of Physics, Center for Biomedical Research, Oakland University, Rochester, MI, USA
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Lee D, Ryu S. A Validation Study of the Repeatability and Accuracy of Atomic Force Microscopy Indentation Using Polyacrylamide Gels and Colloidal Probes. J Biomech Eng 2017; 139:2595195. [DOI: 10.1115/1.4035536] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Indexed: 01/06/2023]
Abstract
The elasticity of soft biological materials is a critical property to understand their biomechanical behaviors. Atomic force microscopy (AFM) indentation method has been widely employed to measure the Young's modulus (E) of such materials. Although the accuracy of the method has been recently evaluated based on comparisons with macroscale E measurements, the repeatability of the method has yet to be validated for rigorous biomechanical studies of soft elastic materials. We tested the AFM indentation method using colloidal probes and polyacrylamide (PAAM) gels of E < 20 kPa as a model soft elastic material after having identified optimal trigger force and probe speed. AFM indentations repeated with time intervals show that the method is well repeatable when performed carefully. Compared with the rheometric method and the confocal microscopy indentation method, the AFM indentation method is evaluated to have comparable accuracy and better precision, although these elasticity measurements appear to rely on the compositions of PAAM gels and the length scale of measurement. Therefore, we have confirmed that the AFM indentation method can reliably measure the elasticity of soft elastic materials.
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Affiliation(s)
- Donghee Lee
- Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588 e-mail:
| | - Sangjin Ryu
- Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588 e-mail:
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Lee H, Campbell WD, Canning ME, Theis KM, Ennis HY, Jackson RL, Wright JC, Hanson RR. Correlation between signalment and the biphasic hyperelastic mechanical properties of equine articular cartilage. ACTA ACUST UNITED AC 2016. [DOI: 10.1016/j.biotri.2016.07.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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19
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20
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de Girolamo L, Niada S, Arrigoni E, Di Giancamillo A, Domeneghini C, Dadsetan M, Yaszemski MJ, Gastaldi D, Vena P, Taffetani M, Zerbi A, Sansone V, Peretti GM, Brini AT. Repair of osteochondral defects in the minipig model by OPF hydrogel loaded with adipose-derived mesenchymal stem cells. Regen Med 2016; 10:135-51. [PMID: 25835479 DOI: 10.2217/rme.14.77] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
AIM Critical knee osteochondral defects in seven adult minipigs were treated with oligo(polyethylene glycol)fumarate (OPF) hydrogel combined with autologous or human adipose-derived stem cells (ASCs), and evaluated after 6 months. METHODS Four defects were made on the peripheral part of right trochleas (n = 28), and treated with OPF scaffold alone or pre-seeded with ASCs. RESULTS A better quality cartilage tissue characterized by improved biomechanical properties and higher collagen type II expression was observed in the defects treated by autologous or human ASC-loaded OPF; similarly this approach induced the regeneration of more mature bone with upregulation of collagen type I expression. CONCLUSION This study provides the evidence that both porcine and human adipose-derived stem cells associated to OPF hydrogel allow improving osteochondral defect regeneration in a minipig model.
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Affiliation(s)
- Laura de Girolamo
- IRCCS Istituto Ortopedico Galeazzi; Via R. Galeazzi 4, 20161 Milano, Italy
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21
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Buffinton CM, Tong KJ, Blaho RA, Buffinton EM, Ebenstein DM. Comparison of mechanical testing methods for biomaterials: Pipette aspiration, nanoindentation, and macroscale testing. J Mech Behav Biomed Mater 2015; 51:367-79. [DOI: 10.1016/j.jmbbm.2015.07.022] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Revised: 07/17/2015] [Accepted: 07/22/2015] [Indexed: 10/23/2022]
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22
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Chen Z, Xu Y, Bujalowski P, Oberhauser AF, Boor PJ. N-(2-Aminoethyl) Ethanolamine-Induced Morphological, Biochemical, and Biophysical Alterations in Vascular Matrix Associated With Dissecting Aortic Aneurysm. Toxicol Sci 2015; 148:421-32. [PMID: 26443843 DOI: 10.1093/toxsci/kfv194] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Dissecting aortic aneurysm (DAA) is an extended tear in the wall of the aorta along the plane of the vascular media. Our previous studies indicated in a developmental animal model, that DAA was related to pathological alteration in collagen, especially collagen type III. Accordingly, in the present studies, neonatal aortic vascular smooth muscle cells (VSMC) and timed pregnant Sprague-Dawley rat dams were treated with N-(2-aminoethyl) ethanolamine (AEEA), which, as shown previously, causes DAA in offspring. Morphological changes in extracellular matrix (ECM) produced by VSMC in vitro were detailed with scanning electron microscopy (SEM), and biochemical changes in cells and ECM produced by VSMCs were defined by Western blotting. Biophysical changes of the collagen extracted from both the ECM produced by VSMC and extracted from fetal rat aortas were studied with atomic force microscopy (AFM). ECM disruption and irregularities were observed in VSMCs treated with AEEA by SEM. Western blotting showed that collagen type I was much more extractable, accompanied by a decrease of the pellet size after urea buffer extraction in the AEEA-treated VSMC when compared with the control. AFM found that collagen samples extracted from the fetal rat aortas of the AEEA-treated dam, and in the in vitro formed ECM prepared by decellularization, became stiffer, or more brittle, indicating that the 3D organization associated with elasticity was altered by AEEA exposure. Our results show that AEEA causes significant morphological, biochemical, and biomechanical alterations in the ECM. These in vitro and in vivo strategies are advantageous in elucidating the underlying mechanisms of DAA.
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Affiliation(s)
| | | | | | - Andres F Oberhauser
- Department of Neuroscience and Cell Biology; and Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, Texas 77555
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Chen X, Zhou Y, Wang L, Santare MH, Wan LQ, Lu XL. Determining Tension-Compression Nonlinear Mechanical Properties of Articular Cartilage from Indentation Testing. Ann Biomed Eng 2015; 44:1148-58. [PMID: 26240062 DOI: 10.1007/s10439-015-1402-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Accepted: 07/18/2015] [Indexed: 11/30/2022]
Abstract
The indentation test is widely used to determine the in situ biomechanical properties of articular cartilage. The mechanical parameters estimated from the test depend on the constitutive model adopted to analyze the data. Similar to most connective tissues, the solid matrix of cartilage displays different mechanical properties under tension and compression, termed tension-compression nonlinearity (TCN). In this study, cartilage was modeled as a porous elastic material with either a conewise linear elastic matrix with cubic symmetry or a solid matrix reinforced by a continuous fiber distribution. Both models are commonly used to describe the TCN of cartilage. The roles of each mechanical property in determining the indentation response of cartilage were identified by finite element simulation. Under constant loading, the equilibrium deformation of cartilage is mainly dependent on the compressive modulus, while the initial transient creep behavior is largely regulated by the tensile stiffness. More importantly, altering the permeability does not change the shape of the indentation creep curves, but introduces a parallel shift along the horizontal direction on a logarithmic time scale. Based on these findings, a highly efficient curve-fitting algorithm was designed, which can uniquely determine the three major mechanical properties of cartilage (compressive modulus, tensile modulus, and permeability) from a single indentation test. The new technique was tested on adult bovine knee cartilage and compared with results from the classic biphasic linear elastic curve-fitting program.
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Affiliation(s)
- Xingyu Chen
- Department of Mechanical Engineering, University of Delaware, 130 Academy Street SPL 126, Newark, DE, 19716, USA
| | - Yilu Zhou
- Department of Mechanical Engineering, University of Delaware, 130 Academy Street SPL 126, Newark, DE, 19716, USA
| | - Liyun Wang
- Department of Mechanical Engineering, University of Delaware, 130 Academy Street SPL 126, Newark, DE, 19716, USA
| | - Michael H Santare
- Department of Mechanical Engineering, University of Delaware, 130 Academy Street SPL 126, Newark, DE, 19716, USA
| | - Leo Q Wan
- Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, NY, 12180, USA
| | - X Lucas Lu
- Department of Mechanical Engineering, University of Delaware, 130 Academy Street SPL 126, Newark, DE, 19716, USA.
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Honkanen JTJ, Danso EK, Suomalainen JS, Tiitu V, Korhonen RK, Jurvelin JS, Töyräs J. Contrast enhanced imaging of human meniscus using cone beam CT. Osteoarthritis Cartilage 2015; 23:1367-76. [PMID: 25865390 DOI: 10.1016/j.joca.2015.03.037] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Revised: 03/06/2015] [Accepted: 03/28/2015] [Indexed: 02/02/2023]
Abstract
OBJECTIVE Meniscal injuries can lead to mechanical overloading of articular cartilage and eventually to knee osteoarthritis. The objective was to evaluate the potential of contrast enhanced computed tomography (CECT) to image contrast agent (CA) diffusion in human menisci with a clinical cone beam CT scanner. DESIGN Isolated human menisci (n = 26) were imaged using magnetic resonance imaging (MRI) and CECT in situ. Diffusion of anionic CA into the meniscus was imaged for up to 30 h. The results of CECT were compared with water, collagen and proteoglycan (PG) contents, biomechanical properties, age and histological and MR images of the samples. RESULTS Diffusion of CA required over 25 h to reach equilibrium. The CA partition (the CA concentration in the tissue divided by that in the bath) at the 40 min time point correlated significantly with that at the 30 h time point in both lateral (r = 0.706, P = 0.007) and medial (r = 0.669, P = 0.012) menisci. Furthermore, CA partition in meniscus after 30 h of diffusion agreed qualitatively with the distribution of PGs. CONCLUSION The cross-sectional distribution of CA was consistent with that reported in a previous μCT study on bovine meniscus. The time required to reach diffusion equilibrium was found impractical for clinical applications. However, based on the present results, shorter delay between injection and imaging (e.g., 40 min) could be feasible in clinical diagnostics of meniscal pathologies.
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Affiliation(s)
- J T J Honkanen
- Department of Applied Physics, University of Eastern Finland, POB 1627, FI-70211, Kuopio, Finland; Diagnostic Imaging Centre, Kuopio University Hospital, KUH, POB 100, FI-70029, Kuopio, Finland.
| | - E K Danso
- Department of Applied Physics, University of Eastern Finland, POB 1627, FI-70211, Kuopio, Finland; Department of Clinical Neurophysiology, Kuopio University Hospital, KUH, POB 100, FI-70029, Kuopio, Finland.
| | - J-S Suomalainen
- Diagnostic Imaging Centre, Kuopio University Hospital, KUH, POB 100, FI-70029, Kuopio, Finland.
| | - V Tiitu
- Institute of Biomedicine, Anatomy, University of Eastern Finland, POB 1627, FI-70211, Kuopio, Finland.
| | - R K Korhonen
- Department of Applied Physics, University of Eastern Finland, POB 1627, FI-70211, Kuopio, Finland; Diagnostic Imaging Centre, Kuopio University Hospital, KUH, POB 100, FI-70029, Kuopio, Finland.
| | - J S Jurvelin
- Department of Applied Physics, University of Eastern Finland, POB 1627, FI-70211, Kuopio, Finland; Diagnostic Imaging Centre, Kuopio University Hospital, KUH, POB 100, FI-70029, Kuopio, Finland.
| | - J Töyräs
- Department of Applied Physics, University of Eastern Finland, POB 1627, FI-70211, Kuopio, Finland; Diagnostic Imaging Centre, Kuopio University Hospital, KUH, POB 100, FI-70029, Kuopio, Finland.
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Mattei G, Gruca G, Rijnveld N, Ahluwalia A. The nano-epsilon dot method for strain rate viscoelastic characterisation of soft biomaterials by spherical nano-indentation. J Mech Behav Biomed Mater 2015; 50:150-9. [PMID: 26143307 DOI: 10.1016/j.jmbbm.2015.06.015] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Revised: 06/12/2015] [Accepted: 06/15/2015] [Indexed: 11/16/2022]
Abstract
Nano-indentation is widely used for probing the micromechanical properties of materials. Based on the indentation of surfaces using probes with a well-defined geometry, the elastic and viscoelastic constants of materials can be determined by relating indenter geometry and measured load and displacement to parameters which represent stress and deformation. Here we describe a method to derive the viscoelastic properties of soft hydrated materials at the micro-scale using constant strain rates and stress-free initial conditions. Using a new self-consistent definition of indentation stress and strain and corresponding unique depth-independent expression for indentation strain rate, the epsilon dot method, which is suitable for bulk compression testing, is transformed to nano-indentation. We demonstrate how two materials can be tested with a displacement controlled commercial nano-indentor using the nano-espilon dot method (nano-ε̇M) to give values of instantaneous and equilibrium elastic moduli and time constants with high precision. As samples are tested in stress-free initial conditions, the nano-ε̇M could be useful for characterising the micro-mechanical behaviour of soft materials such as hydrogels and biological tissues at cell length scales.
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Affiliation(s)
- G Mattei
- Research Centre "E. Piaggio", University of Pisa, Largo Lucio Lazzarino 1, 56122 Pisa, Italy
| | - G Gruca
- Optics11, De Boelelaan 108, 1081 HV Amsterdam, The Netherlands
| | - N Rijnveld
- Optics11, De Boelelaan 108, 1081 HV Amsterdam, The Netherlands
| | - A Ahluwalia
- Research Centre "E. Piaggio", University of Pisa, Largo Lucio Lazzarino 1, 56122 Pisa, Italy.
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Taffetani M, Raiteri R, Gottardi R, Gastaldi D, Vena P. A quantitative interpretation of the response of articular cartilage to atomic force microscopy-based dynamic nanoindentation tests. J Biomech Eng 2015; 137:2212353. [PMID: 25807472 DOI: 10.1115/1.4030175] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Indexed: 11/08/2022]
Abstract
In this paper, a quantitative interpretation for atomic force microscopy-based dynamic nanoindentation (AFM-DN) tests on the superficial layers of bovine articular cartilage (AC) is provided. The relevant constitutive parameters of the tissue are estimated by fitting experimental results with a finite element model in the frequency domain. Such model comprises a poroelastic stress-strain relationship for a fibril reinforced tissue constitution, assuming a continuous distribution of the collagen network orientations. The identification procedure was first validated using a simplified transversely isotropic constitutive relationship; then, the experimental data were manually fitted by using the continuous distribution fibril model. Tissue permeability is derived from the maximum value of the phase shift between the input harmonic loading and the harmonic tissue response. Tissue parameters related to the stiffness are obtained from the frequency response of the experimental storage modulus and phase shift. With this procedure, an axial to transverse stiffness ratio (anisotropy ratio) of about 0.15 is estimated.
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Gibson RF, Jang HK, Simkhada S, Yu Q, Kim HI, Suhr J. Use of Nanoindentation, Finite Element Simulations, and a Combined Experimental/Numerical Approach to Characterize Elastic Moduli of Individual Porous Silica Particles. PARTICULATE SCIENCE AND TECHNOLOGY 2015. [DOI: 10.1080/02726351.2014.950396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Lee H, Kirkland WG, Whitmore RN, Theis KM, Young HE, Richardson AJ, Jackson RL, Hanson RR. Comparison of equine articular cartilage thickness in various joints. Connect Tissue Res 2014; 55:339-47. [PMID: 25111191 DOI: 10.3109/03008207.2014.949698] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
PURPOSE Thicknesses of fresh equine articular cartilage surfaces from the fetlock, carpal and stifle joints were measured employing a needle probe test. MATERIALS AND METHODS Eighty-seven samples used in measurement were cultivated from fetlock, carpal and stifle joints of 12 deceased within 4 h of death. After approximately three minutes of exposure to air during dissection, all cartilage samples were preserved in a saline solution to keep the articular cartilage hydrated for testing. The thickness was measured on five different spots on the same sample. The thicknesses of the fetlock, carpus and stifle were compared. RESULTS The articular cartilage of the stifle was thicker than the fetlock and carpus, while the fetlock and the carpus had similar thickness values. The average thickness of the fetlock, carpal and stifle joint are 0.86, 0.87 and 2.1 mm, respectively. They were statistically compared using the Student t-test. The differences on the articular cartilage thicknesses between the fetlock and stifle, and carpus and stifle were "very highly significant" (p < 0.001). This indicates that the articular cartilage thickness of the stifle is significantly different from that of the fetlock and carpus. Four different surfaces in the fetlock and four in the carpal joint were also compared. Significant differences between each set of the four surfaces were not observed. In the carpus, the difference in thickness between the distal radius and proximal third carpal bone articular cartilage surfaces as well as the proximal radial carpal bone and distal radial carpal bone articular cartilage surfaces were statistically significant.
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Affiliation(s)
- Hyeon Lee
- Department of Mechanical Engineering, Auburn University , Auburn, AL , USA and
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Taffetani M, Gottardi R, Gastaldi D, Raiteri R, Vena P. Poroelastic response of articular cartilage by nanoindentation creep tests at different characteristic lengths. Med Eng Phys 2014; 36:850-8. [DOI: 10.1016/j.medengphy.2014.03.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2013] [Revised: 02/14/2014] [Accepted: 03/23/2014] [Indexed: 10/25/2022]
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Irianto J, Ramaswamy G, Serra R, Knight MM. Depletion of chondrocyte primary cilia reduces the compressive modulus of articular cartilage. J Biomech 2013; 47:579-82. [PMID: 24345381 PMCID: PMC3899052 DOI: 10.1016/j.jbiomech.2013.11.040] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2013] [Revised: 11/20/2013] [Accepted: 11/24/2013] [Indexed: 02/05/2023]
Abstract
Primary cilia are slender, microtubule based structures found in the majority of cell types with one cilium per cell. In articular cartilage, primary cilia are required for chondrocyte mechanotransduction and the development of healthy tissue. Loss of primary cilia in Col2aCre;ift88(fl/fl) transgenic mice results in up-regulation of osteoarthritic (OA) markers and development of OA like cartilage with greater thickness and reduced mechanical stiffness. However no previous studies have examined whether loss of primary cilia influences the intrinsic mechanical properties of articular cartilage matrix in the form of the modulus or just the structural properties of the tissue. The present study describes a modified analytical model to derive the viscoelastic moduli based on previous experimental indentation data. Results show that the increased thickness of the articular cartilage in the Col2aCre;ift88(fl/fl) transgenic mice is associated with a reduction in both the instantaneous and equilibrium moduli at indentation strains of greater than 20%. This reveals that the loss of primary cilia causes a significant reduction in the mechanical properties of cartilage particularly in the deeper zones and possibly the underlying bone. This is consistent with histological analysis and confirms the importance of primary cilia in the development of a mechanically functional articular cartilage.
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Affiliation(s)
- Jerome Irianto
- Institute of Bioengineering and School of Engineering and Materials Science, Queen Mary University of London, Mile End Rd, London E1 4NS, United Kingdom
| | - Girish Ramaswamy
- Department of Orthopedic Surgery, Perelman School of Medicine, University of Pennsylvania, PA, USA
| | - Rosa Serra
- Arthritis & Musculoskeletal Diseases Center, UAB School of Medicine and Dentistry, Birmingham, AL, USA
| | - Martin M Knight
- Institute of Bioengineering and School of Engineering and Materials Science, Queen Mary University of London, Mile End Rd, London E1 4NS, United Kingdom.
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Lindburg CA, Willey JS, Dean D. Effects of low dose X-ray irradiation on porcine articular cartilage explants. J Orthop Res 2013; 31:1780-5. [PMID: 23913833 PMCID: PMC3792489 DOI: 10.1002/jor.22406] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Accepted: 05/19/2013] [Indexed: 02/04/2023]
Abstract
Ionizing radiation therapy is a crucial treatment for cancer, but can damage surrounding normal tissues. Damage to articular cartilage leading to arthropathy can occur at irradiated sites. It is unclear whether this response is due to damaging surrounding skeletal structures or direct effects on cartilage. In this study, we showed that irradiation with 2 Gy of X-rays causes a significant reduction in the stiffness of porcine explants 1 week post-irradiation. By using both microindentation and indentation-type atomic force microscopy, ionizing radiation reduces stiffness in both the superficial zone, and throughout the entire thickness of the tissue. Young's modulus values were 75% and 60% lower in 2 Gy irradiated samples when compared with controls using microindentation and nanoindentation, respectively. Glycosaminoglycans (GAGs) released into the culture media of irradiated samples was nearly 100% greater at 24 h after exposure. While collagen content in the tissue is similar between groups, GAG content is 55% lower in irradiated explants compared with controls 7 days after exposure. Therefore, the irradiated explants are unable to recover from the initial loss of GAGs by 1 week. This acute loss of GAGs is a likely contributor to the reduction in modulus seen after exposure to ionizing radiation.
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Affiliation(s)
| | - Jeffrey S. Willey
- Department of Radiation Oncology, Wake Forest School of Medicine, Winston-Salem, NC
| | - Delphine Dean
- Department of Bioengineering, Clemson University, Clemson, SC
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Xiao Y, Friis EA, Gehrke SH, Detamore MS. Mechanical testing of hydrogels in cartilage tissue engineering: beyond the compressive modulus. TISSUE ENGINEERING. PART B, REVIEWS 2013; 19:403-12. [PMID: 23448091 PMCID: PMC3752504 DOI: 10.1089/ten.teb.2012.0461] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Accepted: 02/08/2013] [Indexed: 11/12/2022]
Abstract
Injuries to articular cartilage result in significant pain to patients and high medical costs. Unfortunately, cartilage repair strategies have been notoriously unreliable and/or complex. Biomaterial-based tissue-engineering strategies offer great promise, including the use of hydrogels to regenerate articular cartilage. Mechanical integrity is arguably the most important functional outcome of engineered cartilage, although mechanical testing of hydrogel-based constructs to date has focused primarily on deformation rather than failure properties. In addition to deformation testing, as the field of cartilage tissue engineering matures, this community will benefit from the addition of mechanical failure testing to outcome analyses, given the crucial clinical importance of the success of engineered constructs. However, there is a tremendous disparity in the methods used to evaluate mechanical failure of hydrogels and articular cartilage. In an effort to bridge the gap in mechanical testing methods of articular cartilage and hydrogels in cartilage regeneration, this review classifies the different toughness measurements for each. The urgency for identifying the common ground between these two disparate fields is high, as mechanical failure is ready to stand alongside stiffness as a functional design requirement. In comparing toughness measurement methods between hydrogels and cartilage, we recommend that the best option for evaluating mechanical failure of hydrogel-based constructs for cartilage tissue engineering may be tensile testing based on the single edge notch test, in part because specimen preparation is more straightforward and a related American Society for Testing and Materials (ASTM) standard can be adopted in a fracture mechanics context.
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Affiliation(s)
- Yinghua Xiao
- Chemical and Petroleum Engineering, University of Kansas, Lawrence, Kansas
| | | | - Stevin H. Gehrke
- Chemical and Petroleum Engineering, University of Kansas, Lawrence, Kansas
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Mayr H, Klehm J, Schwan S, Hube R, Südkamp N, Niemeyer P, Salzmann G, von Eisenhardt-Rothe R, Heilmann A, Bohner M, Bernstein A. Microporous calcium phosphate ceramics as tissue engineering scaffolds for the repair of osteochondral defects: biomechanical results. Acta Biomater 2013; 9:4845-55. [PMID: 22885682 DOI: 10.1016/j.actbio.2012.07.040] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2012] [Revised: 07/23/2012] [Accepted: 07/26/2012] [Indexed: 10/28/2022]
Abstract
This work investigated the suitability of microporous β-tricalcium phosphate (TCP) scaffolds pre-seeded with autologous chondrocytes for treatment of osteochondral defects in a large animal model. Microporous β-TCP cylinders (Ø 7 mm; length 25 mm) were seeded with autologous chondrocytes and cultured for 4 weeks in vitro. Only the upper end of the cylinder was seeded with chondrocytes. Chondrocytes formed a multilayer on the top. The implants were then implanted in defects (diameter 7 mm) created in the left medial femoral condyle of ovine knees. The implants were covered with synovial membrane from the superior recess of the same joint. For the right knees, an empty defect with the same dimensions served as control. Twenty-eight sheep were split into 6-, 12-, 26- and 52 week groups of seven animals. Indentation tests with a spherical (Ø 3mm) indenter were used to determine the biomechanical properties of regenerated tissue. A software-based limit switch was implemented to ensure a maximal penetration depth of 200 μm and maximal load of 1.5 N. The achieved load, the absorbed energy and the contact stiffness were measured. Newly formed cartilage was assessed with the International Cartilage Repair Society Visual Assessment Scale (ICRS score) and histomorphometric analysis. Results were analysed statistically using the t-test, Mann-Whitney U-test and Wilcoxon test. Statistical significance was set at p<0.05. After 6 weeks of implantation, the transplanted area tolerated an indentation load of 0.05±0.20 N. This value increased to 0.10±0.06 N after 12 weeks, to 0.27±0.18 N after 26 weeks, and 0.27±0.11 N after 52 weeks. The increase in the tolerated load was highly significant (p<0.0001), but the final value was not significantly different from that of intact cartilage (0.30±0.12 N). Similarly, the increase in contact stiffness from 0.87±0.29 N mm-(1) after 6 weeks to 3.14±0.86 N mm(-1) after 52 weeks was highly significant (p<0.0001). The absorbed energy increased significantly (p=0.02) from 0.74×10(-6)±0.38×10(-6) Nm after 6 weeks to 2.83×10(-6)±1.35×10(-6) Nm after 52 weeks. At 52 weeks, the International Cartilage Repair Society (ICRS) scores for the central area of the transplanted area and untreated defects were comparable. In contrast, the score for the area from the edge to the centre of the transplanted area was significantly higher (p=0.001) than the score for the unfilled defects. A biomechanically stable cartilage was built outside the centre of defect. After 52 weeks, all but one empty control defect were covered by bone and a very thin layer of cartilage (ICRS 7 points). The empty hole could still be demonstrated beneath the bone. The histomorphometric evaluation revealed that 81.0±10.6% of TCP was resorbed after 52 weeks. The increase in TCP resorption and replacement by spongy bone during the observation period was highly significant (p<0.0001). In this sheep trial, the mechanical properties of microporous TCP scaffolds seeded with transplanted autologous chondrocytes were similar to those of natural cartilage after 52 weeks of implantation. However, the central area of the implants had a lower ICRS score than healthy cartilage. Microporous TCP was almost fully resorbed at 52 weeks and replaced by bone.
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Smyth PA, Rifkin RE, Jackson RL, Reid Hanson R. The fractal structure of equine articular cartilage. SCANNING 2012; 34:418-426. [PMID: 22753326 DOI: 10.1002/sca.21026] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Accepted: 03/28/2012] [Indexed: 06/01/2023]
Abstract
The naturally occurring structure of articular cartilage has proven to be an effective means for the facilitation of motion and load support in equine and other animal joints. Cartilage has been found to be a complex and dynamic medium, which has led to an incomplete understanding of the nature and operating mechanisms acting within a joint. Although cartilage has biphasic and triphasic properties, it is believed that the performance of equine articular joints is influenced by the surface roughness of the joint cartilage (Ateshian et al., '98; Chan et al., 2011; Yao and Unsworth, '93). Various joint types with different motions and regimes of lubrication have altered demands on the articular surface that may affect cartilage surface properties. In research performed on freshly harvested samples, equine articular cartilage has been shown to possess a multiscale structure and a fractal dimension. It is thought that by determining the fractal dimension (D) of articular cartilage, a better understanding of the friction, wear, and lubrication mechanisms for biomechanic surfaces can eventually be reached. This study looks at the fractal dimensions of three different articular cartilage surfaces in the equine carpus: the radiocarpal, midcarpal, and carpometacarpal surfaces. The three surfaces provide an ideal comparison of fractal dimensions for a different range of motion, geometry, and loading. In each sample, identical treatment was performed during measurement by a stylus profilometer.
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Affiliation(s)
- Patrick A Smyth
- Department of Mechanical Engineering, Auburn University, Auburn, Alabama, USA
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35
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Mechano-rheological properties of the murine thrombus determined via nanoindentation and finite element modeling. J Mech Behav Biomed Mater 2012; 10:75-86. [DOI: 10.1016/j.jmbbm.2012.02.012] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2011] [Revised: 01/31/2012] [Accepted: 02/18/2012] [Indexed: 11/18/2022]
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Smyth PA, Rifkin RE, Jackson RL, Hanson RR. A Surface Roughness Comparison of Cartilage in Different Types of Synovial Joints. J Biomech Eng 2012; 134:021006. [DOI: 10.1115/1.4005934] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The naturally occurring structure of articular cartilage has proven to be an effective means for the facilitation of motion and load support in equine and other animal joints. For this reason, cartilage has been extensively studied for many years. Although the roughness of cartilage has been determined from atomic force microscopy (AFM) and other methods in multiple studies, a comparison of roughness to joint function has not be completed. It is hypothesized that various joint types with different motions and regimes of lubrication have altered demands on the articular surface that may affect cartilage surface properties. Micro- and nanoscale stylus profilometry was performed on the carpal cartilage harvested from 16 equine forelimbs. Eighty cartilage surface samples taken from three different functioning joint types (radiocarpal, midcarpal, and carpometacarpal) were measured by a Veeco Dektak 150 Stylus Surface Profilometer. The average surface roughness measurements were statistically different for each joint. This indicates that the structure of cartilage is adapted to, or worn by, its operating environment. Knowledge of cartilage micro- and nanoscale roughness will assist the future development and design of treatments for intra- articular substances or surfaces to preserve joint integrity and reduce limitations or loss of joint performance.
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Affiliation(s)
- Patrick A. Smyth
- Department of Mechanical Engineering, Auburn University, Auburn, AL, 36849
| | - Rebecca E. Rifkin
- College of Veterinary Medicine, Auburn University, Auburn, AL, 36849
| | - Robert L. Jackson
- Department of Mechanical Engineering, Auburn University, Auburn, AL, 36849
| | - R. Reid Hanson
- College of Veterinary Medicine, Auburn University, Auburn, AL, 36849
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Mercadé-Prieto R, Zhang Z. Mechanical characterization of microspheres – capsules, cells and beads: a review. J Microencapsul 2012; 29:277-85. [DOI: 10.3109/02652048.2011.646331] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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38
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Whitcomb JE, Amini R, Simha NK, Barocas VH. Anterior-posterior asymmetry in iris mechanics measured by indentation. Exp Eye Res 2011; 93:475-81. [PMID: 21787771 DOI: 10.1016/j.exer.2011.06.009] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2010] [Revised: 06/13/2011] [Accepted: 06/14/2011] [Indexed: 11/17/2022]
Abstract
Indentation and histological analysis of the porcine iris were done to assess the relative stiffness of the anterior (stroma) and posterior (dilator and sphincter) layers. The dimensions of the constituent structures were documented histologically by staining with a monoclonal anti-human α-smooth muscle actin antibody to determine the location of the stroma, sphincter, and dilator. Intact porcine irides (4-8 h post-mortem) were bisected into two equal C-shaped halves to indent both surfaces. Indentation experiments were performed using a 1 mm cylindrical indenter tip. The load-displacement curve for each experiment was used to estimate effective instantaneous and equilibrium moduli for the anterior and posterior surfaces of the tissue. A total of 18 irides (9 pairs) with 3-5 indentations per iris surface was performed. The average thickness of the samples was 550 μm; the indentation depth was limited to 60-100 μm depending on the thickness of the sample at each point. Posterior surface indentation gave larger forces than anterior, with the resulting instantaneous modulus of 6.0 ± 0.6 kPa versus 4.0 ± 0.5 kPa (mean ± 95% CI, n = 45, p < 0.001) and equilibrium modulus of 4.4 ± 0.9 versus 2.3 ± 0.3 (p = 0.007). The stress-relaxation analysis revealed that the anterior surface had a shorter relaxation time (121.31 ± 6.84 s) than the posterior surface (210.61 ± 9.41 s, p = 0.03), perhaps due to the permeability of the stroma. Recognizing that our effective modulus calculations in this study did not account for heterogeneity, viscoelasticity, or poroelasticity, we conclude that the posterior components of the iris - dilator, pigment epithelium, and sphincter - are on average stiffer than the stroma and anterior border layer.
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Affiliation(s)
- Julie E Whitcomb
- Department of Mechanical Engineering, University of Minnesota, Minneapolis, MN 55455, USA.
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Waldman SD, Usprech J, Flynn LE, Khan AA. Harnessing the purinergic receptor pathway to develop functional engineered cartilage constructs. Osteoarthritis Cartilage 2010; 18:864-72. [PMID: 20346406 DOI: 10.1016/j.joca.2010.03.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2009] [Revised: 02/15/2010] [Accepted: 03/04/2010] [Indexed: 02/02/2023]
Abstract
OBJECTIVE Mechanical stimulation is a widely used method to enhance the formation and properties of tissue-engineered cartilage. While this approach can be highly successful, it may be more efficient and effective to harness the known underlying mechanotransduction pathways responsible. With this aim, the purpose of this study was to assess the effect of directly stimulating the purinergic receptor pathway through exogenous adenosine 5'-triphosphate (ATP) in absence of externally applied forces. METHODS Isolated bovine articular chondrocytes were seeded in high density, 3D culture and supplemented with varying doses of ATP for up to 4 weeks. The effects on biosynthesis, extracellular matrix accumulation and mechanical properties were then evaluated. Experiments were also conducted to assess whether exogenous ATP elicited any undesirable effects, such as: inflammatory mediator release, matrix turn-over and mineralization. RESULTS Supplementation with ATP had a profound effect on the growth and maturation of the developed tissue. Exogenous ATP (62.5-250 microM) increased biosynthesis by 80-120%, and when stimulated for a period of 4 weeks resulted in increased matrix accumulation (80% increase in collagen and 60% increase in proteoglycans) and improved mechanical properties (6.5-fold increase in indentation modulus). While exogenous ATP did not stimulate the release of inflammatory mediators or induce mineralization, high doses of ATP (250 microM) elicited a 2-fold increase in matrix metalloproteinase-13 expression suggesting the emergence of a catabolic response. CONCLUSIONS Harnessing the ATP-purinergic receptor pathway is a highly effective approach to improve tissue formation and impart functional mechanical properties. However, the dose of ATP needs to be controlled as not to elicit a catabolic response.
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Affiliation(s)
- S D Waldman
- Department of Mechanical and Materials Engineering, Queen's University, Kingston, Ontario, Canada.
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40
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Kaufman JD, Klapperich CM. Surface detection errors cause overestimation of the modulus in nanoindentation on soft materials. J Mech Behav Biomed Mater 2009; 2:312-7. [DOI: 10.1016/j.jmbbm.2008.08.004] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2008] [Revised: 07/25/2008] [Accepted: 08/13/2008] [Indexed: 10/21/2022]
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Hall ML, Krawczak DA, Simha NK, Lewis JL. Effect of dermatan sulfate on the indentation and tensile properties of articular cartilage. Osteoarthritis Cartilage 2009; 17:655-61. [PMID: 19036614 PMCID: PMC2717628 DOI: 10.1016/j.joca.2008.10.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2008] [Accepted: 10/22/2008] [Indexed: 02/02/2023]
Abstract
OBJECTIVE This paper examines the hypothesis that the dermatan sulfate (DS) chain on decorin is a load carrying element in cartilage and that its damage or removal will alter the material properties. METHODS To test this hypothesis, indentation and tensile testing of cartilage from bovine patella were performed before and after digestion with chondroitinase B (cB). Removal of significant amounts of DS by cB digestion was verified by Western blot analysis of proteoglycans extracted from whole and sectioned specimens. Specimens (control and treated) were subjected to a series of step-hold displacements. Elastic modulus during the step rise (rapid modulus) and at equilibrium (equilibrium modulus), and the relaxation function during each step was measured for test (cB and buffer) and control (buffer alone) conditions. RESULTS cB had no effect on any of the viscoelastic mechanical properties measured, either in indentation or tension. CONCLUSION Removing or damaging approximately 50% of the DS had no effect on the mechanical properties, strongly suggesting that DS either carries very low load or no load.
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Affiliation(s)
- M L Hall
- Department of Orthopaedic Surgery, University of Minnesota, Minneapolis, MN 55455, USA
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Julkunen P, Harjula T, Marjanen J, Helminen HJ, Jurvelin JS. Comparison of single-phase isotropic elastic and fibril-reinforced poroelastic models for indentation of rabbit articular cartilage. J Biomech 2009; 42:652-6. [PMID: 19193381 DOI: 10.1016/j.jbiomech.2008.12.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2008] [Revised: 12/11/2008] [Accepted: 12/11/2008] [Indexed: 10/21/2022]
Abstract
Classically, single-phase isotropic elastic (IE) model has been used for in situ or in vivo indentation analysis of articular cartilage. The model significantly simplifies cartilage structure and properties. In this study, we apply a fibril-reinforced poroelastic (FRPE) model for indentation to extract more detailed information on cartilage properties. Specifically, we compare the information from short-term (instantaneous) and long-term (equilibrium) indentations, as described here by IE and FRPE models. Femoral and tibial cartilage from rabbit (age 0-18 months) knees (n=14) were tested using a plane-ended indenter (diameter=0.544 mm). Stepwise creep tests were conducted to equilibrium. Single-phase IE solution for indentation was used to derive instantaneous modulus and equilibrium (Young's) modulus for the samples. The classical and modified Hayes' solutions were used to derive values for the indentation moduli. In the FRPE model, the indentation behavior was sample-specifically described with three material parameters, i.e. fibril network modulus, non-fibrillar matrix modulus and permeability. The instantaneous and fibril network modulus, and the equilibrium Young's modulus and non-fibrillar matrix modulus showed significant (p<0.01) linear correlations of R(2)=0.516 and 0.940, respectively (Hayes' solution) and R(2)=0.531 and 0.960, respectively (the modified Hayes' solution). No significant correlations were found between the non-fibrillar matrix modulus and instantaneous moduli or between the fibril network modulus and the equilibrium moduli. These results indicate that the instantaneous indentation modulus (IE model) provides information on tensile stiffness of collagen fibrils in cartilage while the equilibrium modulus (IE model) is a significant measure for stiffness of PG matrix. Thereby, this study highlights the feasibility of a simple indentation analysis.
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Affiliation(s)
- Petro Julkunen
- Department of Clinical Neurophysiology, Kuopio University Hospital, Kuopio, Finland.
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Chiravarambath S, Simha NK, Namani R, Lewis JL. Poroviscoelastic Cartilage Properties in the Mouse From Indentation. J Biomech Eng 2008; 131:011004. [DOI: 10.1115/1.3005199] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A method for fitting parameters in a poroviscoelastic (PVE) model of articular cartilage in the mouse is presented. Indentation is performed using two different sized indenters and then these data are fitted using a PVE finite element program and parameter extraction algorithm. Data from a smaller indenter, a 15μm diameter flat-ended 60deg cone, is first used to fit the viscoelastic (VE) parameters, on the basis that for this tip size the gel diffusion time (approximate time constant of the poroelastic (PE) response) is of the order of 0.1s, so that the PE response is negligible. These parameters are then used to fit the data from a second 170μm diameter flat-ended 60deg cone for the PE parameters, using the VE parameters extracted from the data from the 15μm tip. Data from tests on five different mouse tibial plateaus are presented and fitted. Parameter variation studies for the larger indenter show that for this case the VE and PE time responses overlap in time, necessitating the use of both models.
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Affiliation(s)
- Sidharth Chiravarambath
- Department of Orthopaedic Surgery, and Department of Aerospace Engineering and Mechanics, University of Minnesota, Minneapolis, MN 55455
| | - Narendra K. Simha
- Department of Orthopaedic Surgery, and Department of Aerospace Engineering and Mechanics, University of Minnesota, Minneapolis, MN 55455
| | - Ravi Namani
- Department of Mechanical, Aerospace, and Structural Engineering, Washington University, St. Louis, MO 63102
| | - Jack L. Lewis
- Department of Orthopaedic Surgery, University of Minnesota, Minneapolis, MN 55455
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Kaufman JD, Miller GJ, Morgan EF, Klapperich CM. Time-dependent mechanical characterization of poly(2-hydroxyethyl methacrylate) hydrogels using nanoindentation and unconfined compression. JOURNAL OF MATERIALS RESEARCH 2008; 23:1472-1481. [PMID: 19081812 PMCID: PMC2600455 DOI: 10.1557/jmr.2008.0185] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Hydrogels pose unique challenges to nanoindentation including sample preparation, control of experimental parameters, and limitations imposed by mechanical testing instruments and data analysis originally intended for harder materials. The artifacts that occur during nanoindentation of hydrated samples have been described, but the material properties obtained from hydrated nanoindentation have not yet been related to the material properties obtained from macroscale testing. To evaluate the best method for correlating results from microscale and macroscale tests of soft materials, nanoindentation and unconfined compression stress-relaxation tests were performed on poly-2-hydroxyethyl methacrylate (pHEMA) hydrogels with a range of cross-linker concentrations. The nanoindentation data were analyzed with the Oliver-Pharr elastic model and the Maxwell-Wiechert (j = 2) viscoelastic model. The unconfined compression data were analyzed with the Maxwell-Wiechert model. This viscoelastic model provided an excellent fit for the stress-relaxation curves from both tests. The time constants from nanoindentation and unconfined compression were significantly different, and we propose that these differences are due to differences in equilibration time between the microscale and macroscale experiments and in sample geometry. The Maxwell-Wiechert equilibrium modulus provided the best agreement between nanoindentation and unconfined compression. Also, both nanoindentation analyses showed an increase in modulus with each increasing cross-linker concentration, validating that nanoindentation can discriminate between similar, low-modulus, hydrated samples.
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Affiliation(s)
| | - Gregory J. Miller
- Department of Aerospace and Mechanical Engineering, Boston University, Boston, Massachusetts 02215
| | - Elise F. Morgan
- Department of Aerospace and Mechanical Engineering, Boston University, Boston, Massachusetts 02215; and Department of Biomedical Engineering, Boston University, Boston, Massachusetts 02215
| | - Catherine M. Klapperich
- Department of Manufacturing Engineering, Boston University, Boston, Massachusetts 02215; and Department of Biomedical Engineering, Boston University, Boston, Massachusetts 02215
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Wang S, Kempen DH, Simha NK, Lewis JL, Windebank AJ, Yaszemski MJ, Lu L. Photo-cross-linked hybrid polymer networks consisting of poly(propylene fumarate) and poly(caprolactone fumarate): controlled physical properties and regulated bone and nerve cell responses. Biomacromolecules 2008; 9:1229-41. [PMID: 18307311 DOI: 10.1021/bm7012313] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Aiming to achieve suitable polymeric biomaterials with controlled physical properties for hard and soft tissue replacements, we have developed a series of blends consisting of two photo-cross-linkable polymers: polypropylene fumarate (PPF) and polycaprolactone fumarate (PCLF). Physical properties of both un-cross-linked and UV cross-linked PPF/PCLF blends with PPF composition ranging from 0% to 100% have been investigated extensively. It has been found that the physical properties such as thermal, rheological, and mechanical properties could be modulated efficiently by varying the PPF composition in the blends. Thermal properties including glass transition temperature (T g) and melting temperature (T m) have been correlated with their rheological and mechanical properties. Surface characteristics such as surface morphology, hydrophilicity, and the capability of adsorbing serum protein from culture medium have also been examined for the cross-linked polymer and blend disks. For potential applications in bone and nerve tissue engineering, in vitro cell studies including cytotoxicity, cell adhesion, and proliferation on cross-linked disks with controlled physical properties have been performed using rat bone marrow stromal cells and SPL201 cells, respectively. In addition, the role of mechanical properties such as surface stiffness in modulating cell responses has been emphasized using this model blend system.
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Affiliation(s)
- Shanfeng Wang
- Department of Materials Science and Engineering, The University of Tennessee, Knoxville, Tennessee 37996, USA
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