Synthesis of apatite-organic polymer hybrid materials by chemical modification

本论文研究了在离子浓度接近人血浆浓度的模拟体液（SBF）或离子浓度为1.5倍的模拟体液（1.5SBF）中，通过仿生合成类骨磷灰石-有机高分子杂化材料。通过与含三乙氧基硅烷基的硅烷偶联剂反应，并通过水解和缩聚反应，对乙烯-乙烯醇共聚物基材和针织纤维表面进行了硅烷醇（Si-OH）改性。硅醇改性后的样品在1.5SBF中几周内即可形成磷灰石层，而硅酸钙溶液处理后的样品在几天内即可形成磷灰石层，说明钙离子引入表面硅酸盐层增强了磷灰石的形成能力.结果表明，由羧甲基纤维素（CM）、羧甲基甲壳素（CM-chitin）和结冷胶（gellan gum）制备的凝胶，经饱和Ca（OH）_2溶液预处理后，在模拟体液中3天内表面就形成了磷灰石。在模拟体液中，含羧基和钙离子的海藻酸钙凝胶和纤维在一周内也形成了磷灰石，说明凝胶上的羧基对磷灰石的成核是有效的，钙离子的引入可以提高聚合物的磷灰石形成能力。通过简单的化学修饰和仿生方法的结合，发现各种类型的聚合物是获得具有骨状结构的磷灰石-聚合物杂化物的有希望的候选物。

In this research was investigated the synthesis of bonelike apatite-organic polymer hybrid materials via a biomimetic process in a simulated body fluid (SBF) with ion concentrations nearly equal to those of human blood plasma or a solution (1.5SBF) with ion concentrations 1.5 times those of SBF.Main results include :1. The surface of ethylene-vinyl alcohol copolymer substrates and knitted fibers were modified with silanol (Si-OH) groups by the reaction with a triethoxysilyl group-containing silane coupling agent and the subsequent hydrolysis and polycondensation of tetraethoxysilane. The silanol-modified specimens were found to form apatite layer on them within a few weeks in 1.5SBF.Moreover, the specimens treated with calcium silicate solution can form apatite within a few days even in SBF, indicating introduction of calcium ions into the surface silicate layer brings about the enhanced apatite-forming ability.2. It was found that the gels prepared from carboxymethyl (CM) cellulose, CM-chitin and gellan gum, all of which possess carboxylate functions, formed apatite on their surfaces within 3 days in SBF, when they were previously treated with a saturated Ca(OH)_2 solution. Calcium alginate gels and fibers originally having carboxyl groups and calcium ions also formed apatite on them within a week in SBF.These results indicate that the carboxylate groups on the gels are effective for the apatite nucleation and the apatite forming ability of the polymer can be improved by incorporation of the calcium ions.In conclusion, various types of polymers were found to be promising candidates for obtaining apatite-polymer hybrids with bonelike structure through a combination of simple chemical modifications and biomimetic process.