Type VI collagen is a non-fibrillar collagen expressed in many connective tissues and implicated ... more Type VI collagen is a non-fibrillar collagen expressed in many connective tissues and implicated in extracellular matrix (ECM) organisation. We hypothesized that type VI collagen regulates matrix assembly and cell function within the dermis of the skin. In the present study we examined the expression pattern of type VI collagen in normal and wounded skin and investigated its specific function in new matrix deposition by human dermal fibroblasts. Type VI collagen was expressed throughout the dermis of intact human skin, at the expanding margins of human keloid samples, and in the granulation tissue of newly deposited ECM in a mouse model of wound healing. Generation of cell derived matrices (CDMs) by human dermal fibroblasts with stable knockdown of COL6A1 revealed that type VI collagen deficient matrices were significantly thinner and contained more aligned, thicker, and widely spaced fibres than CDMs produced by normal fibroblasts. In addition, there was significantly less total collagen and sulfated proteoglycans present in the type VI collagen depleted matrices. Normal fibroblasts cultured on de-cellularised CDMs lacking type VI collagen displayed increased cell spreading, migration speed, and persistence. Taken together, these findings indicate that type VI collagen is a key regulator of dermal matrix assembly, composition, and fibroblast behaviour and may play an important role in wound healing and tissue regeneration.Journal of Investigative Dermatology accepted article preview online, 09 September 2015. doi:10.1038/jid.2015.352.
Journal of the mechanical behavior of biomedical materials, Jan 9, 2015
The lamellar unit is a critical component in defining the overall mechanical properties of bone. ... more The lamellar unit is a critical component in defining the overall mechanical properties of bone. In this paper, micro-beams of bone with dimensions comparable to the lamellar unit were fabricated using focused ion beam (FIB) microscopy and mechanically tested in bending to failure using atomic force microscopy (AFM). A variation in the mechanical properties, including elastic modulus, strength and work to fracture of the micro-beams was observed and related to the collagen fibril orientation inferred from back-scattered scanning electron microscopy (SEM) imaging. Established mechanical models were further applied to describe the relationship between collagen fibril orientation and mechanical behaviour of the lamellar unit. Our results highlight the ability to measure mechanical properties of discrete bone volumes directly and correlate with structural orientation of collagen fibrils.
Polymer nanofibres produced by electrospinning techniques have unique mechanical properties due t... more Polymer nanofibres produced by electrospinning techniques have unique mechanical properties due to their large surface area to volume ratio and potentially high molecular orientation. The effects of temperature on mechanical properties is challenging to measure due to the small fibre diameters produced. In this paper, scanning probe microscopy (SPM) is successfully used to elucidate the mechanical performance of individual electrospun
Wetting behavior between electrospun nanofibrous networks and liquids is of critical importance i... more Wetting behavior between electrospun nanofibrous networks and liquids is of critical importance in many applications including filtration and liquid-repellent textiles. The relationship between intrinsic nanofiber properties, including surface characteristics, and extrinsic nanofibrous network organization on resultant wetting characteristics of the nanofiber network is shown in this work. Novel 3D imaging exploiting focused ion beam (FIB) microscopy and cryo-scanning electron microscopy (cryo-SEM) highlights a wetting hierarchy that defines liquid interactions with the network. Specifically, small length scale partial wetting between individual electrospun nanofibers and low surface tension liquids, measured both using direct SEM visualization and a nano Wilhelmy balance approach, provides oleophobic surfaces due to the high porosity of electrospun nanofiber networks. These observations conform to a metastable Cassie–Baxter regime and are important in defining general rules for understanding the wetting behavior between fibrous solids and low surface tension liquids for omniphobic functionality.
Type VI collagen is a non-fibrillar collagen expressed in many connective tissues and implicated ... more Type VI collagen is a non-fibrillar collagen expressed in many connective tissues and implicated in extracellular matrix (ECM) organisation. We hypothesized that type VI collagen regulates matrix assembly and cell function within the dermis of the skin. In the present study we examined the expression pattern of type VI collagen in normal and wounded skin and investigated its specific function in new matrix deposition by human dermal fibroblasts. Type VI collagen was expressed throughout the dermis of intact human skin, at the expanding margins of human keloid samples, and in the granulation tissue of newly deposited ECM in a mouse model of wound healing. Generation of cell derived matrices (CDMs) by human dermal fibroblasts with stable knockdown of COL6A1 revealed that type VI collagen deficient matrices were significantly thinner and contained more aligned, thicker, and widely spaced fibres than CDMs produced by normal fibroblasts. In addition, there was significantly less total collagen and sulfated proteoglycans present in the type VI collagen depleted matrices. Normal fibroblasts cultured on de-cellularised CDMs lacking type VI collagen displayed increased cell spreading, migration speed, and persistence. Taken together, these findings indicate that type VI collagen is a key regulator of dermal matrix assembly, composition, and fibroblast behaviour and may play an important role in wound healing and tissue regeneration.Journal of Investigative Dermatology accepted article preview online, 09 September 2015. doi:10.1038/jid.2015.352.
Journal of the mechanical behavior of biomedical materials, Jan 9, 2015
The lamellar unit is a critical component in defining the overall mechanical properties of bone. ... more The lamellar unit is a critical component in defining the overall mechanical properties of bone. In this paper, micro-beams of bone with dimensions comparable to the lamellar unit were fabricated using focused ion beam (FIB) microscopy and mechanically tested in bending to failure using atomic force microscopy (AFM). A variation in the mechanical properties, including elastic modulus, strength and work to fracture of the micro-beams was observed and related to the collagen fibril orientation inferred from back-scattered scanning electron microscopy (SEM) imaging. Established mechanical models were further applied to describe the relationship between collagen fibril orientation and mechanical behaviour of the lamellar unit. Our results highlight the ability to measure mechanical properties of discrete bone volumes directly and correlate with structural orientation of collagen fibrils.
Polymer nanofibres produced by electrospinning techniques have unique mechanical properties due t... more Polymer nanofibres produced by electrospinning techniques have unique mechanical properties due to their large surface area to volume ratio and potentially high molecular orientation. The effects of temperature on mechanical properties is challenging to measure due to the small fibre diameters produced. In this paper, scanning probe microscopy (SPM) is successfully used to elucidate the mechanical performance of individual electrospun
Wetting behavior between electrospun nanofibrous networks and liquids is of critical importance i... more Wetting behavior between electrospun nanofibrous networks and liquids is of critical importance in many applications including filtration and liquid-repellent textiles. The relationship between intrinsic nanofiber properties, including surface characteristics, and extrinsic nanofibrous network organization on resultant wetting characteristics of the nanofiber network is shown in this work. Novel 3D imaging exploiting focused ion beam (FIB) microscopy and cryo-scanning electron microscopy (cryo-SEM) highlights a wetting hierarchy that defines liquid interactions with the network. Specifically, small length scale partial wetting between individual electrospun nanofibers and low surface tension liquids, measured both using direct SEM visualization and a nano Wilhelmy balance approach, provides oleophobic surfaces due to the high porosity of electrospun nanofiber networks. These observations conform to a metastable Cassie–Baxter regime and are important in defining general rules for understanding the wetting behavior between fibrous solids and low surface tension liquids for omniphobic functionality.
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