Department of Materials, Imperial College London, South Kensington Campus, London SW7 2AZ, UK.
Acta Biomater. 2013 Aug;9(8):7662-71. doi: 10.1016/j.actbio.2013.04.037. Epub 2013 Apr 28.
Bioactive glasses and inorganic/organic hybrids have great potential as biomedical implant materials. Sol-gel hybrids with interpenetrating networks of silica and biodegradable polymers can combine the bioactive properties of a glass with the toughness of a polymer. However, traditional calcium sources such as calcium nitrate and calcium chloride are unsuitable for hybrids. In this study calcium was incorporated by chelation to the polymer component. The calcium salt form of poly(γ-glutamic acid) (γCaPGA) was synthesized for use as both a calcium source and as the biodegradable toughening component of the hybrids. Hybrids of 40wt.% γCaPGA were successfully formed and had fine scale integration of Ca and Si ions, according to secondary ion mass spectrometry imaging, indicating a homogeneous distribution of organic and inorganic components. (29)Si magic angle spinning nuclear magnetic resonance data demonstrated that the network connectivity was unaltered with changing polymer molecular weight, as there was no perturbation to the overall Si speciation and silica network formation. Upon immersion in simulated body fluid a hydroxycarbonate apatite surface layer formed on the hybrids within 1week. The polymer molecular weight (Mw 30-120kDa) affected the mechanical properties of the resulting hybrids, but all hybrids had large strains to failure, >26%, and compressive strengths, in excess of 300MPa. The large strain to failure values showed that γCaPGA hybrids exhibited non-brittle behaviour whilst also incorporating calcium. Thus calcium incorporation by chelation to the polymer component is justified as a novel approach in hybrids for biomedical materials.
生物活性玻璃和无机/有机杂化材料在生物医学植入材料方面具有巨大的潜力。具有二氧化硅和可生物降解聚合物互穿网络的溶胶-凝胶杂化材料可以将玻璃的生物活性与聚合物的韧性结合起来。然而，传统的钙源，如硝酸钙和氯化钙，不适合用于杂化材料。在本研究中，钙通过与聚合物组分螯合来掺入。聚（γ-谷氨酸）（γCaPGA）的钙盐形式被合成，用作钙源和杂化材料的可生物降解增韧组分。成功地形成了 40wt.%γCaPGA 的杂化材料，根据二次离子质谱成像，其具有 Ca 和 Si 离子的精细尺度集成，表明有机和无机成分的均匀分布。（29）Si 魔角旋转核磁共振数据表明，网络连接性没有随聚合物分子量的变化而改变，因为对整体 Si 形态和二氧化硅网络形成没有干扰。在模拟体液中浸泡 1 周后，杂化材料表面形成了羟基碳酸磷灰石层。聚合物分子量（Mw 30-120kDa）影响了所得杂化材料的机械性能，但所有杂化材料的断裂应变均超过 26%，压缩强度超过 300MPa。大的断裂应变值表明，γCaPGA 杂化材料在掺入钙的同时表现出非脆性行为。因此，通过与聚合物组分螯合来掺入钙被证明是生物医学材料杂化材料中的一种新方法。
