Study of the Morphological and Adhesion Properties of Collagen Fibers in the Bruch's Membrane

Mallick, Shrestha Basu; Ivanisevic, Albena

doi:10.1021/jp053605w

Cited by 13 publications

(19 citation statements)

References 36 publications

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“…Because of this, AFM is gaining popularity in ophthalmology and has been used to image other basement membranes in the eye. 1,8,9,13,24,25,46 The images obtained in the current study are similar to those acquired of other basement membranes in the eye: a dense interwoven fibrous structure separated by openings on the order of a micron.…”

Section: Discussionsupporting

confidence: 74%

Fractal Analysis of AFM Images of the Surface of Bowman’s Membrane of the Human Cornea

et al. 2014

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The objective of this study is to further investigate the ultrastructural details of the surface of Bowman's membrane of the human cornea, using atomic force microscopy (AFM) images. One representative image acquired of Bowman's membrane of a human cornea was investigated. The three-dimensional (3-D) surface of the sample was imaged using AFM in contact mode, while the sample was completely submerged in optisol solution. Height and deflection images were acquired at multiple scan lengths using the MFP-3D AFM system software (Asylum Research, Santa Barbara, CA), based in IGOR Pro (WaveMetrics, Lake Oswego, OR). A novel approach, based on computational algorithms for fractal analysis of surfaces applied for AFM data, was utilized to analyze the surface structure. The surfaces revealed a fractal structure at the nanometer scale. The fractal dimension, D, provided quantitative values that characterize the scale properties of surface geometry. Detailed characterization of the surface topography was obtained using statistical parameters, in accordance with ISO 25178-2: 2012. Results obtained by fractal analysis confirm the relationship between the value of the fractal dimension and the statistical surface roughness parameters. The surface structure of Bowman's membrane of the human cornea is complex. The analyzed AFM images confirm a fractal nature of the surface, which is not taken into account by classical surface statistical parameters. Surface fractal dimension could be useful in ophthalmology to quantify corneal architectural changes associated with different disease states to further our understanding of disease evolution.

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Section: Discussionsupporting

confidence: 74%

Fractal Analysis of AFM Images of the Surface of Bowman’s Membrane of the Human Cornea

et al. 2014

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“…Furthermore, an understanding of the collagen Type II assembly represents an important first initial step on the road to the use of collagenous scaffolds in tissue engineering that might be used for cartilage replacement surgery in the future. Finally, the hierarchical self-assembly of collagen provides a methodology for constructing molecular systems into functional macroscopic materials with well-organized structures.Most knowledge about the fibrillation of fibril-forming collagens have been obtained by studying collagen Type I through a variety of techniques, such as X-ray diffraction, [5] transmission electron microscopy (TEM) [6][7][8][9] and atomic force microscopy (AFM). [10][11][12][13] From these studies it has been concluded that the fibrillation process is entropy driven, [14] and that the formation of D-banded fibrils is observed at temperatures above 21°C.…”

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confidence: 99%

Temporal Assembly of Collagen Type II Studied by Atomic Force Microscopy

Dong

Bünger

et al. 2007

Adv Eng Mater

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Collagen is a key structural protein in several types of tissues including skin, bone and cartilage. [1]. The collagen family currently includes twenty-six different types of collagen, [2] which can be divided into fibril-forming collagens and fibrilassociated collagens with interrupted triple helices (FACITcollagens). [3] Collagen Type II is one of the fibril-forming collagens and the predominant type of collagen in cartilage [1] . The fibril-forming collagens, including collagen Type II, display a characteristic D-band structure due to a staggered arrangement of the molecules in the fibrils. [4] The fibrils are formed by the assembly of tropocollagen molecules, which consist of three polypeptide strands in a triple helical arrangement. In-vitro studies of the nanoscale molecular assembly of collagen Type II is of great interest, since such studies provide fundamental microscopic insights into how the fibrils assemble in vivo. Furthermore, an understanding of the collagen Type II assembly represents an important first initial step on the road to the use of collagenous scaffolds in tissue engineering that might be used for cartilage replacement surgery in the future. Finally, the hierarchical self-assembly of collagen provides a methodology for constructing molecular systems into functional macroscopic materials with well-organized structures.Most knowledge about the fibrillation of fibril-forming collagens have been obtained by studying collagen Type I through a variety of techniques, such as X-ray diffraction, [5] transmission electron microscopy (TEM) [6][7][8][9] and atomic force microscopy (AFM). [10][11][12][13] From these studies it has been concluded that the fibrillation process is entropy driven, [14] and that the formation of D-banded fibrils is observed at temperatures above 21°C. While the formation of collagen Type I is fairly well understood, this is not the case for collagen Type II. [3,[15][16][17] In vivo collagen Type II is secreted as procollagen molecules that are enzymatically processed by the removal of their C-and N-propeptides before or during fibril assembly in the extracellular matrix. [17] The assembly process is influenced by interaction with small proteoglycans and other matrix proteins such as cartilage oligomeric matrix protein (COMP), collagen type IX and collagen type XI. [3,[18][19][20][21] However, other factors such as pH, electrolytes, molecule concentration and temperature are critical environmental parameters for the fibrillation process. [7,22] In the present study we have used high-resolution AFM to study in vitro the hierarchical self-assembly of collagen Type II and to investigate how the temporal collagen assembly process is influenced by the incubation time, temperature, pH and the collagen Type II concentration under physiological buffer conditions. Three different collagen Type II assembly regimes that result in D-banded fibrils through distinct hierarchical supramolecular assemblies are revealed. Experimental SectionSample preparations were performed using commerci...

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“…Regional variations in adhesion properties of Bruch's membrane (located below the retina) have been related to the variable distribution of several types of collagen within the Bruch's membrane. 24 Although several types of collagen are found in the sclera, Type I is the predominant form. 12 Our adhesion data (Figure 3(a)) suggest that our AFM measurements are not influenced by local surface chemistry.…”

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confidence: 99%

Nanoscale characterization of the biomechanical properties of collagen fibrils in the sclera

Papi

Paoletti²,

Geraghty³

et al. 2014

Applied Physics Letters

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We apply the PeakForce Quantitative Nanomechanical Property Mapping (PFQNM) atomic force microscopy mode for the investigation of regional variations in the nanomechanical properties of porcine sclera. We examine variations in the collagen fibril diameter, adhesion, elastic modulus and dissipation in the posterior, equatorial and anterior regions of the sclera. The mean fibril diameter, elastic modulus and dissipation increased from the posterior to the anterior region. Collagen fibril diameter correlated linearly with elastic modulus. Our data matches the known macroscopic mechanical behavior of the sclera. We propose that PFQNM has significant potential in ocular biomechanics and biophysics research.

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Study of the Morphological and Adhesion Properties of Collagen Fibers in the Bruch's Membrane

Cited by 13 publications

References 36 publications

Fractal Analysis of AFM Images of the Surface of Bowman’s Membrane of the Human Cornea

Fractal Analysis of AFM Images of the Surface of Bowman’s Membrane of the Human Cornea

Temporal Assembly of Collagen Type II Studied by Atomic Force Microscopy

Nanoscale characterization of the biomechanical properties of collagen fibrils in the sclera

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