A small angle light scattering device for planar connective tissue microstructural analysis

Sacks, Michael S.; Smith, David B.; Hiester, Erik D.

doi:10.1007/bf02684845

Cited by 258 publications

(205 citation statements)

References 21 publications

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“…For collagen in bovine pericardium, at low strain, the Poisson's ratio appears to have a very high value (15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27), but for strain above 0.09, the Poisson's ratio is in the range 2.1-2.8. For the total strain (from 0 to 0.25), the change in d-spacing and diameter gives 0 ¼ 2.1 6 0.7 (these values of 0 can be calculated from Fig.…”

Section: Resultsmentioning

confidence: 96%

Poisson's ratio of collagen fibrils measured by small angle X-ray scattering of strained bovine pericardium

Wells

Sizeland

Kayed

et al. 2015

Journal of Applied Physics

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Type I collagen is the main structural component of skin, tendons, and skin products, such as leather. Understanding the mechanical performance of collagen fibrils is important for understanding the mechanical performance of the tissues that they make up, while the mechanical properties of bulk tissue are well characterized, less is known about the mechanical behavior of individual collagen fibrils. In this study, bovine pericardium is subjected to strain while small angle X-ray scattering (SAXS) patterns are recorded using synchrotron radiation. The change in d-spacing, which is a measure of fibril extension, and the change in fibril diameter are determined from SAXS. The tissue is strained 0.25 (25%) with a corresponding strain in the collagen fibrils of 0.045 observed. The ratio of collagen fibril width contraction to length extension, or the Poisson's ratio, is 2.1 ± 0.7 for a tissue strain from 0 to 0.25. This Poisson's ratio indicates that the volume of individual collagen fibrils decreases with increasing strain, which is quite unlike most engineering materials. This high Poisson's ratio of individual fibrils may contribute to high Poisson's ratio observed for tissues, contributing to some of the remarkable properties of collagen-based materials.

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Section: Resultsmentioning

confidence: 96%

Poisson's ratio of collagen fibrils measured by small angle X-ray scattering of strained bovine pericardium

Wells

Sizeland

Kayed

et al. 2015

Journal of Applied Physics

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“…1 B). The first section was used to measure the extracellular matrix fiber alignment over the entire area of the specimen using the SALS technique (36). Briefly, the specimen was glycerol-dehydrated in graded solutions of glycerol and saline for 1 h. The fiber ODFs were recorded and then fitted by a dual Gaussian distribution function.…”

Section: Optical and Histological Measurementsmentioning

confidence: 99%

On the Presence of Affine Fibril and Fiber Kinematics in the Mitral Valve Anterior Leaflet

Lee

Zhang

Liao

et al. 2015

Biophysical Journal

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In this study, we evaluated the hypothesis that the constituent fibers follow an affine deformation kinematic model for planar collagenous tissues. Results from two experimental datasets were utilized, taken at two scales (nanometer and micrometer), using mitral valve anterior leaflet (MVAL) tissues as the representative tissue. We simulated MVAL collagen fiber network as an ensemble of undulated fibers under a generalized two-dimensional deformation state, by representing the collagen fibrils based on a planar sinusoidally shaped geometric model. The proposed approach accounted for collagen fibril amplitude, crimp period, and rotation with applied macroscopic tissue-level deformation. When compared to the small angle x-ray scattering measurements, the model fit the data well, with an r 2 ¼ 0.976. This important finding suggests that, at the homogenized tissue-level scale of~1 mm, the collagen fiber network in the MVAL deforms according to an affine kinematics model. Moreover, with respect to understanding its function, affine kinematics suggests that the constituent fibers are largely noninteracting and deform in accordance with the bulk tissue. It also suggests that the collagen fibrils are tightly bounded and deform as a single fiber-level unit. This greatly simplifies the modeling efforts at the tissue and organ levels, because affine kinematics allows a straightforward connection between the macroscopic and local fiber strains. It also suggests that the collagen and elastin fiber networks act independently of each other, with the collagen and elastin forming long fiber networks that allow for free rotations. Such freedom of rotation can greatly facilitate the observed high degree of mechanical anisotropy in the MVAL and other heart valves, which is essential to heart valve function. These apparently novel findings support modeling efforts directed toward improving our fundamental understanding of tissue biomechanics in healthy and diseased conditions.

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“…A detailed description of the SALS technique has been previously presented [38]. Briefly, a 4 mW HeNe continuous unpolarized laser (λ = 632.8 nm) was passed through the tissue specimen.…”

Section: Small Angle Light Scattering (Sals) Measurementsmentioning

confidence: 99%

“…where NOI ranged from 0% for a complete random network to 100% for a perfectly aligned network [38].…”

Section: Small Angle Light Scattering (Sals) Measurementsmentioning

confidence: 99%

Effects of decellularization on the mechanical and structural properties of the porcine aortic valve leaflet

2008

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The potential for decellularized aortic heart valves (AVs) as heart valve replacements is based on the assumption that the major cellular immunogenic components have been removed, and that the remaining extracellular matrix (ECM) should retain the necessary mechanical properties and functional design. However, decellularization processes likely alter the ECM mechanical and structural properties, potentially affecting long term durability. In the present study we explored the effects of an anionic detergent (SDS), enzymatic agent (Trypsin), and a non-ionic detergent (Triton X-100) on the mechanical and structural properties of AV leaflets (AVLs) to provide greater insight into the initial functional state of the decellularized AVL. The overall extensibility represented by the areal strain under 60 N/m increased from 68.85% for the native AV to 139.95%, 137.51%, and 177.69% for SDS, Trypsin, and Triton X-100, respectively, after decellularization. In flexure, decellularized AVLs demonstrated a profound loss of stiffness overall, and also produced a nonlinear moment-curvature relation compared to the linear response of the native AVL. Effective flexural moduli decreased from 156.0±24.6 kPa for the native AV to 23.5±5.8 kPa, 15.6±4.8 kPa, and 19.4 ±8.9 kPa for SDS, Trypsin, and Triton X-100 treated leaflets, respectively. While the overall leaflet fiber architecture remained relatively unchanged, decellularization resulted in substantial microscopic disruption. In conclusion, changes in mechanical and structural properties of decellularized leaflets were likely associated with disruption of the ECM, which may impact the durability of the leaflets.

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A small angle light scattering device for planar connective tissue microstructural analysis

Cited by 258 publications

References 21 publications

Poisson's ratio of collagen fibrils measured by small angle X-ray scattering of strained bovine pericardium

Poisson's ratio of collagen fibrils measured by small angle X-ray scattering of strained bovine pericardium

On the Presence of Affine Fibril and Fiber Kinematics in the Mitral Valve Anterior Leaflet

Effects of decellularization on the mechanical and structural properties of the porcine aortic valve leaflet

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