Inorganic phase, bone

Industrial catalysts, connections of supported nanoclusters to, 72 Inorganic phase, bone, 132 Integrins... 

Diagenesis of the inorganic phase of cortical bone. In Price, T.D., ed.. Bone Chemistry and Past Behaviour. Cambridge, Cambridge University Press 211-229. 

Composites made with carbon nanostructures have demonstrated their high performance as biomaterials, basically applied in the field of tissue regeneration with excellent results. For example, P.R. Supronowicz et al. demonstrated that nanocomposites fabricated with polylactic acid and CNTs can be used to expose cells to electrical stimulation, thus promoting osteoblast functions that are responsible for the chemical composition of the organic and inorganic phases of bone [277]. MacDonald et al. prepared composites containing a collagen matrix CNTs and found that CNTs do not affect the cell viability or cell proliferation [278]. 

Table 1.35 Composition and Selected Properties of Inorganic Phases in Adult Human Enamel, Dentine, and Bone...

The inorganic phase of bones or teeth is mainly hydroxyapatite (HA), and deviation in Ca/P ratio from common HA (Ca/P = 1.667) is explained by the presence of amorphous phosphates3). The biogenetic HA resembles in size crystals of HA prepared by precipitation from aqueous solutions. The chemical composition of biominerals is similar to HA. However, crystals in bone, dentine and enamel can vary... 

Matrices of mineralized tissues may be subdivided 67) into (a) permanent ones which (4a) remain within the tissue, continuing to enclose the inorganic phase (e. g. mineralized keratins, bone, cementum, shells and dentine) and (b) temporary matrices which (4b) eventually leave the inorganic crystallites in a comparatively unprotected state, exposed to the influence of the external environment (e. g. dental enamel). 

Bones act as a reservoir of certain ions, in particular Ca and PO/1". which readily exchange between bones and blood. Bone structure comprises a strong organic matrix combined with an inorganic phase which is principally hydroxyapatite, 3 CadPO/l- CaiOHH. Bones contain two forms of hydroxyapatite. The less soluble crystalline form contributes to the rigidity of the structure. The crystals are quite stable, hut because of the small size present a very large surface area available lor rapid... 

The nature of mineral phases present in bone, dentin, enamel and other phosphatic tissues, and their mode of formation have been subjects of lively discussions among health scientists and crystallographers. Bioscientists most commonly accept the viewpoint that the inorganic phase of bones or teeth is principally hydroxyapatite, Caio(P04)6(OH)2, and deviation in Ca/P ratio from common hydroxyapatite (Ca/P = 1.667) observed in mineralized tissues is explained by the presence of amorphous phosphates. In contrast, many crystallographers favor the idea of carbonate apatite, i.e. dahllite, as the major crystalline phase in biophosphates and they doubt the existence of amorphous phases. The topic has been reviewed14,15,22,28, 37,44,47,348-358) no common consent has yet been reached. In the following an attempt is made to at least coordinate the controversial findings. 

One of the important fields where carbohydrate polymer/inorganic hybrids may be successfully applied is bioactive materials, e.g., artificial bones expedient for surgery to accelerate the recovery of living bones. There has been increasing interest in hydroxyapatite (HAp) deposition onto the matrix surface of cellulose or related polysaccharide. HAp is a form of calcium phosphate, a main constituent of the inorganic phase of human bone. This kind of study is also a step on the way to exploitation of new biomimetic mineralization methods. 

There are three distinct biological minerals in an individual tooth, viz. enamel, dentin, and cementum. The chemical composition of dentin is quite similar to that of bone, containing 70 wt% of inorganic phase, 20 wt% of organic matrix and 10 wt% of water.83 The inorganic phase of tooth... 

The effects of pH on racemization rates of free amino acids in aqueous solution are complex (21). However, when bone fragments were heated at 100°C in solutions of pH 2-9, the rate constant for aspartic acid racemization was essentially independent of pH (37). It was proposed that the phosphate from the bone s inorganic phase acts as a buffer. This same buffering action would take place in a bone under natural conditions of burial as well. 

Given the advantages of incorporation of an inorganic phase into a polymeric matrix, the G5-glass has been combined with a 95L/5DL-PLA in order to develop a nonporous 2D fully resorbable composite material that could be used in different load-bearing bone-repairing situations. 

Araujo et al. (2008) prepared PCL electrospun nanofiber meshes coated with a biomimetic calcium phosphate (BCP) layer that mimics the extracellular microenvironment found in the human bone structure. The deposition of a calcium phosphate layer, similar to the inorganic phase of bone, on the PCL nanofiber meshes was... 

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