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Applications of Biomaterials in Hard Tissue Replacement
Published in Yaser Dahman, Biomaterials Science and Technology, 2019
Bone is a rigid organ that forms part of the vertebral skeleton. The bones support and protect the various organs of the body, produce red and white blood cells, store minerals, and allow mobility. The bone tissue is a kind of dense connective tissue. Bones have a variety of shapes and sizes and have a complex internal and external structure. They are lightweight but strong and hard and serve multiple functions. Mineralized bone tissue or bone tissue is of two types: cortical and spongy, giving it rigidity and a three-dimensional internal coral structure. Additional kinds of tissue present in bones includes marrow, endosteum, periosteum, nerves, blood vessels, and cartilage.
Development of biomimetic electrospun polymeric biomaterials for bone tissue engineering. A review
Published in Journal of Biomaterials Science, Polymer Edition, 2019
Sugandha Chahal, Anuj Kumar, Fathima Shahitha Jahir Hussian
Bone is an extremely dense connective tissue, which exhibits many levels (i.e. 7 levels) [54] of hierarchical structures, from macro to sub-nano scales. Despite the high levels of hierarchical structures, the smallest building blocks in bone nanostructure, i.e. the mineralized collagen fibrils embedded in the soft protein matrix, have high mechanical properties. The mechanical properties of cancellous human bone especially depend on its porous structure where; the compressive strength is in the range of 2–12 MPa, tensile strength 10–20 MPa, and elastic modulus 0.05–0.5 GPa [43,48]. Table 2 shows the mechanical properties of compact human bone, that has almost 20% higher compressive strength as compared to cancellous bone. Collagen fibrils have contributed to the main mechanical strength to human bone. However, bone minerals also have significant role in providing the mechanical strength of bone as the Young’s modulus increases significantly with high content of Ca that finally improves the yield strain [55].
A human pericardium biopolymeric scaffold for autologous heart valve tissue engineering: cellular and extracellular matrix structure and biomechanical properties in comparison with a normal aortic heart valve
Published in Journal of Biomaterials Science, Polymer Edition, 2018
Frantisek Straka, David Schornik, Jaroslav Masin, Elena Filova, Tomas Mirejovsky, Zuzana Burdikova, Zdenek Svindrych, Hynek Chlup, Lukas Horny, Matej Daniel, Jiri Machac, Jelena Skibová, Jan Pirk, Lucie Bacakova
The surface parts of the HP and the NAV had different cellular structures [Figures 2, 3a and 3b]. Mesothelial cells with microvilli, which secrete the pericardial fluid that lubricates the surface of the pericardial cavity, formed a monolayer of flattened squamous-like epithelial cells. These cells were observed on the surface of the inner layer of the serous pericardium, and lined the pericardial sac. These cells rest on a thin basement membrane supported by dense connective tissue, and were stained positive for cytoskeletal proteins vimentin (a type III intermediate filament protein), α-SMA and β-catenin (a part of a protein complex that creates adherens junctions that are important for maintaining epithelial cell tissue layers and barriers). However, the mesothelial cells were negative for the CD31 endothelial cell marker. Adipose tissue with capillaries composed of endothelial cells that stained positively for CD31 and beta-catenin was present on the outer side of the fibrous HP. The NAV leaflets were covered with valvular endothelial cells (VECs), which were positively stained for CD31 and β-catenin and negatively stained for vimentin and α-SMA.
Morphological computation in haptic sensation and interaction: from nature to robotics
Published in Advanced Robotics, 2018
Julius E. Bernth, Van Anh Ho, Hongbin Liu
Some animals rely on tactile perception to compensate for reduced visibility, particularly in aquatic environments. For example, manatees are almost blind but possess highly receptive sensory fields for navigation and detection of prey underwater [49]. Manatees’ detection of mechano-sensory stimuli is reported to be due to the morphology of vibrissae, or tactile hairs, distributed all over their body. According to authors in [50], manatees have a large portion of their vibrissae distributed around their face (about 2000) compared to their entire body (about 5300). This is different to most other mammals, which only have vibrissae on face (rats’ whiskers, for example). Differing from the structure of ordinary hair, follicles that are accompanied with vibrissae have ‘blood sinus, dense connective tissue capsule, and variety of mechanoreceptors’, known as follicle-sinus complexes (FSCs) [49]. The tissues of FSCs, buried underneath the skin, have a noticeable capsule-like shape which can accommodate a wide range of nerve endings [51]. This includes Merkel endings, novel trabecular endings and tangential endings, all of which have low mechano-sensory thresholds. This results in highly a sensitive and large receptive field on the manatee’s face (Figure 4). Thanks to the dense population of Merkel endings inside FSCs, it is hypothesised that manatees are able to detect the direction of follicle deflection [49], a perception of which human hairy cutaneous skin is incapable.