Synthesis of Nanosized and Microporous Precipitated Hydroxyapatite in Synthetic Polymers and Biopolymers

Abstract

In situ precipitation of microporous and nanosized hydroxyapatite particles (5–40 nm) has been conducted in poly(vinyl alcohol) and bovine serum albumin gels. The process, which is similar to biomineralization, is highly controlled with respect to microstructural features, such as size and shape, and to precipitation of hydroxyapatite phase having a calcium:phosphorus stoichiometric ratio of 1.67. Nanosized precipitated hydroxyapatite particles show remarkable thermal stability and do not decompose to other calcium phosphate phases, even at higher temperatures.

Nanodimensional and Nanocrystalline Calcium Orthophosphates

“…Another approach comprises precipitation of nanodimensional apatites from aqueous solutions in the presence of dissolved high molecular weight polyacrylic acid [488,489] that acts as an inhibitor for the crystallization of apatite crystals [490,491]. A similar inhibiting effect was found for dimethyl acetamide [492], polyvinyl alcohol [291] and several other (bio)polymers [493,494]. This type of synthesis is expected to lead to formation of nanodimensional composites, which might be structurally more comparable to bones with closely related mechanical and biological properties.…”

Biocomposites and hybrid biomaterials based on calcium orthophosphates

“…These studies covered biocomposites with PLA 663 and many other biocompatible hybrid formulations. 279,320,335,417,[664][665][666][667][668][669][670][671][672][673][674][675][676][677][678][679][680][681][682][683] Furthermore, each of the aforementioned formulations might be covered by a layer of nanodimensional calcium orthophosphate, as was done by Zandi et al, who coated a biocomposite of nano-sized rods HA with gelatin by nano-sized HA. Several nanodimensional biocomposites were found to be applicable as carriers for delivery of drugs and growth factors 38,685-687 and were promising as vectors with ultra high gene loading and transfection efficiency.…”

Calcium orthophosphates (CaPO 4 ): Occurrence and properties

“…That is why, in literature, it might be called as ''precipitated HA (PHA)'' (Sinha et al 2003;Mayer et al 2003). Besides, it might be prepared by hydrolysis of a-TCP (TenHuisen and Brown 1998;Durucan andBrown 2000, 2002).…”