Hydroxyapatite fibers

Thomson, R. C. et al.. Hydroxyapatite fiber reinforced poly(a-hydroxy ester) foams for bone regeneration. Biomaterials, 19, 1935, 1998. 

Yiquan Wu, Larry L. Hench, Jing Du, Kwang-Leong Choy and Jingkun Guo, Preparation of Hydroxyapatite Fibers by Electrospinning Technique, J. Am. Ceram. Soc., 87,1988-1991 (2004). 

Ota, Y., Iwashita, T., Kasuga, T. and Abe, Y. (1998) Novel preparation method of hydroxyapatite fibers. Journal of the American Ceramic Society, 81, 1665-8. 

Kasuga T, Ota Y, Nogami M, Abe Y. Preparation and mechanical properties of polylactic acid composites containing hydroxyapatite fibers. Biomaterials 2001 22 19-23. 

There are several reports on the coating of bone-like hydroxyapatite onto natural polymer substrates. Kawashita et at. [57] reported that carboxymethylated chitin and gellan gum gels, which have carboxyl groups, can form hydroxyapatite on their surfaces in SBF if they are treated with a saturated Ca(OH)2 solution in advance, while curdlan gel, which has no carboxyl group, does not form hydroxyapatite in SBF, even if it is treated with Ca(OH)2 solution. These results support the hypothesis that carboxyl groups induce hydroxyapatite nucleation. Kokubo et at. [58,59] reported that non-woven fabrics of carboxymethylated chitin and alginate fibers also form hydroxyapatite on their surfaces in SBF if they are treated with Ca(OH)2 solution. 

Takeuchi et at. [60] reported that cloth made of raw silk (R-silk) fiber forms hydroxyapatite in 1.5SBF but cloth made of normal silk (N-silk) fiber does not. The surfaces of raw silk and normal silk fibers consist of sericin and fibroin, respectively. 

The collagen fibers leave small compartments where apatite nanocrystals are deposited during a controlled biomineralization process [20]. The collagen acts as a structural framework in which plate-like nanocrystals of carbonated hydroxyapatite (CHA) are embedded to strengthen the bone. The chemical formula of biological CHA can be represented as follows ... 

Hydroxyapatite constitutes -65% of human bone by weight. There is another 18% collagen fiber which makes the bone flexible and more durable. Then, there is -10% genetic tissue (mostly living bone cells). This tissue carries the genetic code of the person or animal and unless it is in a denatured form, which also kills the bone, it is likely to be rejected in the body as a bone graft. Therefore, it is impossible to successfully implant living bone even from closely related donors. The remainder of bone is composed of capillaries, nerves, and so on. 

Another example is LIBS application for real-time identification of carious teeth (Samek et al. 2003). In the dental practice, usually more healthy tissue is removed than ultimately necessary. Carious and healthy tooth material can be identified through the decrease of matrix elements Ca and P in hydroxyapatite and/or the increase of non-matrix elements, typically Li, Sr, Ba, Na, Mg, Zn and C, using pattern recognition algorithms. A fiber-based LIBS assembly was successfully used for this task. As for the case of phosphate ores evaluation, the efforts aimed at normalizing the spectrum collection conditions and procedures, so that the spectra are sufficiently reproducible for precise quantitative... 

Fiber-guided integration and morphogenesis of inorganic constituents e.g. hydroxyapatite, silica or metels (Ag, Au)... 

The spaces between the ends of the tropocollagen molecules in a collagen fiber (see Fig. 4) are the nucleation sites for the deposition of a form of calcium phosphate, hydroxyapatite, in bone formation. Further hydroxyapatite is added until the nucleation sites grow and join with one another to form the mature bone structure. 

In the calcification process of bone formation, the initial crystals of hydroxyapatite are found at intervals of 67 nm along the collagen fiber. What is the reason for this ... 

Bone is an anisotropic and viscoelastic ceramic matrix composite and is distinct from conventional ceramics. Its mechanical properties depend on its porosity, degree of mineralization, collagen fiber orientation, and other structural details. The data in Table 18.1 may be used to compare the physical and mechanical properties of bone, hydroxyapatite (the major mineral in bone, and hence, the most relevant material as a bioceramic), and CBPCs. 

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