Department of Polymer Engineering, 3B's Research Group-Biomaterials, Biodegradables and Biomimetics, University of Minho, Campus de Gualtar, Braga, Portugal.
J Biomed Mater Res A. 2009 Nov;91(2):489-504. doi: 10.1002/jbm.a.32221.
Blends of chitosan and synthetic aliphatic polyesters (polybutylene succinate, polybutylene succinate adipate, polycaprolactone, and polybutylene terepthalate adipate) were compounded with and without hydroxyapatite, a bioactive mineral filler known to enhance osteoconduction. The blends and composites were compression molded with two different granulometric salt sizes (63-125 microm and 250-500 microm) having different levels of salt content (60, 70, and 80%) by weight. By leaching the salt particles, it was possible to produce porous scaffolds with distinct morphologies. The relationship between scaffold morphology and mechanical properties was evaluated using scanning electron microscopy, microcomputed tomography, compression testing, differential scanning calorimetry, small-angle X-ray scattering (SAXS), and wide-angle X-ray scattering. The produced scaffolds are characterized by having different morphologies depending on the average particle size and the amount of NaCl used. Specimens with higher porosity level have a less organized pore structure but increased interconnectivity of the pores. The stress-strain curve under compression displayed a linear elasticity followed by a plateau whose characteristics depend on the scaffold polymer composition. A decrease in the salt particle size used to create the porosity caused in general a decrease in the mechanical properties of the foams. Composites with hydroxyapatite had a sharp reduction in yield stress, modulus, and strain at break. The melting temperature decreased with increased chitosan content. SAXS results indicate no preferential crystalline orientation in the scaffolds. Cytotoxicity evaluation were carried out using standard tests (accordingly to ISO/EN 10993 part 5 guidelines), namely MTS test with a 24-h extraction period, revealing that L929 cells had comparable metabolic activities to that obtained for the negative control.
壳聚糖与合成脂肪族聚酯（聚丁二酸丁二醇酯、聚丁二酸丁二醇酯己二酸酯、聚己内酯和聚对苯二甲酸丁二醇酯己二酸酯）的混合物与羟基磷灰石（一种已知能增强骨传导的生物活性矿物填料）混合，无论是否含有羟基磷灰石。将混合物和复合材料用两种不同粒径的盐（63-125 微米和 250-500 微米）压缩成型，盐的含量（按重量计为 60%、70%和 80%）不同。通过浸出盐颗粒，可以生产出具有不同形态的多孔支架。使用扫描电子显微镜、微计算机断层扫描、压缩测试、差示扫描量热法、小角 X 射线散射（SAXS）和广角 X 射线散射评估支架形态与机械性能之间的关系。所生产的支架具有不同的形态，这取决于平均粒径和使用的 NaCl 量。具有较高孔隙率水平的样品具有较不规整的孔结构，但增加了孔的连通性。压缩下的应力-应变曲线显示出线性弹性，随后是一个平台，其特征取决于支架聚合物组成。用于产生孔隙率的盐颗粒尺寸减小通常会导致泡沫的机械性能降低。含有羟基磷灰石的复合材料的屈服应力、模量和断裂伸长率急剧下降。熔融温度随壳聚糖含量的增加而降低。SAXS 结果表明，支架中没有优先的结晶取向。使用标准测试（根据 ISO/EN 10993 第 5 部分指南）进行细胞毒性评估，即 MTS 测试和 24 小时提取期，结果表明 L929 细胞的代谢活性与阴性对照相当。
