Nano hydroxyapatite different

Its topography reveals the unique structure consisting of aligned prisms or rods with 5pm diameter that extent approximately perpendicular from the dentin-enamel junction towards the tooth surface. Each rod consists of tightly packed carbonated hydroxyapatite crystals with very high aspect ratio. Nano-indentation studies revealed a pronounced anisotropy as the stiffness differs parallel and perpendicular to the rod extension. Even so, different fibre orientation on a micro level as shown in Figure 3.4b account for a quasi-isotropic behaviour. 

Bones offer a classical example of hierarchically organized architecture from nano-scale, where the collagen/hydroxyapatite nanocomposite is organized in fibrils, and fibrils are then laid in different textures, to the microscopic one where a regular organization of cells (osteocytes) and matrix around blood vessels constitutes the basic structure of compact bone (the so-called Haversian system or osteon). 

Colorimetric assays are appropriate methods to investigate protein interactions with cationic polysaccharide materials. However, these assays cannot differentiate between different types of interactions, i.e. adsorption and absorption of proteins. Among these, the bicinchoninic acid assay (BCA) is widely used since it allows an easy determination of the total amount of adsorbed proteins on bulk materials." The assay is based on the reduction of Cu to Cu in a reductive environment in the presence of proteins. The BCA chelates Cu, forming a colored complex whose absorption band at 562 nm can be related to the amount of adsorbed proteins on the materials. Using this method, it has been demonstrated that the incorporation of inorganic materials such as hydroxyapatite (HAP) or nano-HAP into chitosan-based materials leads to the formation of protein-rich layers at the... 

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