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Harland D.P.,Agresearch Ltd. | Caldwell J.P.,Environment Waikato | Woods J.L.,Agresearch Ltd. | Walls R.J.,Agresearch Ltd. | Bryson W.G.,Leather and Shoe Research Association of New Zealand
Journal of Structural Biology | Year: 2011

Tomograms of transverse sections of Merino wool fibers obtained from fleeces differing in fiber curvature were reconstructed from image series collected using a 300. kV transmission electron microscope. Trichokeratin intermediate filaments (IFs) from the ortho-, para- and mesocortices were modeled from the tomograms. IFs were predominantly arranged in left-handed concentric helices with the relative angle of IFs increasing progressively from the center to the periphery of orthocortex macrofibrils. The median increase in IF angle between adjacent IFs between the center and periphery was 2.5°. The length of one turn of the helical path of an IF was calculated to be approximately 1μm for an IF tilted at 30° and positioned 100. nm from the macrofibril center. With the exception of one paracortex macrofibril that weakly resembled an orthocortex macrofibril, all para- and mesocortex macrofibrils modeled had a parallel arrangement of the IFs, with a more ordered arrangement found in the mesocortex. Within the limited sample set, there appeared to be no significant relationship between IF angle and fiber curvature. We examined the matrix/IF ratio (in the form of proportion of matrix to one IF, calculated from IF center-to-center distance and IF diameter) for 28 macrofibrils used for modeling. The proportion of matrix was significantly different in the different cortex cell types, with paracortex having the most (0.61), orthocortex having the least (0.42), and mesocortex being intermediate (0.54). Fibers of different crimp type (high, medium or low crimp) were not significantly different from each other with respect to matrix proportion. © 2010 Elsevier Inc. Source

Sizeland K.H.,Massey University | Basil-Jones M.M.,Massey University | Edmonds R.L.,Leather and Shoe Research Association of New Zealand | Cooper S.M.,Leather and Shoe Research Association of New Zealand | And 3 more authors.
Journal of Agricultural and Food Chemistry | Year: 2013

Collagen is the main structural component of leather, skin, and some other applications such as medical scaffolds. All of these materials have a mechanical function, so the manner in which collagen provides them with their strength is of fundamental importance and was investigated here. This study shows that the tear strength of leather across seven species of mammals depends on the degree to which collagen fibrils are aligned in the plane of the tissue. Tear-resistant material has the fibrils contained within parallel planes with little crossover between the top and bottom surfaces. The fibril orientation is observed using small-angle X-ray scattering in leather, produced from skin, with tear strengths (normalized for thickness) of 20-110 N/mm. The orientation index, 0.420-0.633, is linearly related to tear strength such that greater alignment within the plane of the tissue results in stronger material. The statistical confidence and diversity of animals suggest that this is a fundamental determinant of strength in tissue. This insight is valuable in understanding the performance of leather and skin in biological and industrial applications. © 2013 American Chemical Society. Source

Lian J.,Leather and Shoe Research Association of New Zealand | Lian J.,Massey University | Lian J.,MacDiarmid Institute for Advanced Materials and Nanotechnology | Agban Y.,University of Auckland | And 13 more authors.
European Polymer Journal | Year: 2016

Collagen based hydrogels have similar properties to native cornea and play an important role in ocular drug delivery. Here we report the preparation of zinc oxide nanoparticle/collagen hydrogels (collagen ZnO/PVP) without the need of an external cross-linking agent. The resulting hydrogels had sufficient mechanical strength to be manipulated and transferred without damaging its structure. Differential scanning calorimetry showed an increase in the denaturation temperature on increasing the ZnO/PVP NPs ratio. Whilst rheological measurements of the collagen hydrogels suggest that strong hydrogels were formed, at high concentration of ZnO/PVP NPs a decrease in G′ can be observed. The responses of retinal epithelial cells (ARPE-19) to the collagen ZnO/PVP hydrogels were examined by cell viability assays and exhibited minimal cytotoxicity. The collagen ZnO/PVP hydrogel might be an excellent candidate for ocular drug delivery applications. © 2016 Elsevier Ltd. All rights reserved. Source

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