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Abstract

The development of organic-inorganic hybrids composed of hydroxyapatite and organic polymers is attractive because of their novelty in being materials that show a bone-bonding ability, i.e. bioactivity, and because they have mechanical properties similar to those of natural bone. The biomimetic process has received much attention for fabricating such a hybrid, where bone-like apatite is deposited under ambient conditions on polymer substrates in a simulated body fluid (SBF) having ion concentrations nearly equal to those of human extracellular fluid or related solutions. It has been shown that the carboxyl group is effective for inducing heterogeneous nucleation of apatite in the body. In the present study, apatite deposition on polyamide films containing various numbers of carboxyl groups was investigated in 1.5 SBF, which had ion concentrations 1.5 times those of a normal SBF. The effect of incorporation of calcium chloride on the formation of apatite was examined. Polyamide films containing <or=33 mol % CaCl(2) did not form apatite, even after soaking in 1.5 SBF for 7 days, and even when the polymer film contained 50 mol % carboxyl group. On the other hand, those modified with >or=40 mass % CaCl(2) formed apatite on their surfaces in 1.5 SBF. The ability of the modified film to form an apatite layer increased, and the adhesion of the apatite layer bonded to the film improved, with increasing carboxyl group content. It is concluded that novel apatite-polyamide hybrids can be prepared by a biomimetic process.

Bioactive ceramic-based materials with designed reactivity for bone tissue regeneration

“…Synthetic polymer substrates are also useful to prepare apatite-polymer composites. We (Miyazaki et al 2003c;Kawai et al 2004) reported that aromatic polyamides containing carboxyl groups (polyamide-COOH) or sulphonic (-SO 3 H) groups (polyamide-SO 3 H; Konagaya & Tokai 2000) show apatite-forming ability in 1.5SBF when they contained CaCl 2 . The amount of apatite formed and the rate of formation increased with increasing amounts of functional groups in the polyamides.…”

Coating of bone-like apatite for development of bioactive materials for bone reconstruction

“…Even synthetic polymer substrates containing carboxyl groups also can be coated with bone-like apatite. Miyazaki et al [75] reported that aromatic polyamides containing carboxyl groups [76] showed apatite-forming ability in 1.5SBF when they contained CaCl 2 (figure 6). The apatite layer formed was attached tightly to the polymer.…”

Preparation of citric acid-modified poly(vinyl alcohol) films for effectively precipitating calcium phosphate particles

“…It was also reported that polyamide films containing carboxy groups have the ability to induce the deposition of HAp crystals. 11 Moreover, the HAp crystals were effectively precipitated on a collagen membrane after immersing into citric acid (CA)-containing SBF. 12 The reason was considered to be that the hydroxyl group of CA could adhere to the collagen membrane through hydrogen bonding with the hydrophilic groups ( e.g.…”