Department of Materials Engineering and Industrial Technologies and BIOtech Research Center, University of Trento, Via Delle Regole 101, Mattarello, 38123 Italy.
J Biomed Mater Res B Appl Biomater. 2011 Nov;99(2):338-49. doi: 10.1002/jbm.b.31905. Epub 2011 Sep 27.
The design and tunability of tissue scaffolds, such as pore size and geometry, is crucial to the success of an engineered tissue replacement. Moreover, the mechanical nature of a tissue scaffold should display properties similar to the tissue of interest; therefore, tunability of the foam mechanical properties is desirable. Polymeric foams prepared using supercritical carbon dioxide as a blowing agent has emerged in recent years as a promising technique to prepare porous scaffolds. While a number of groups have reported on the tailoring of scaffold morphologies by using gas foaming techniques, few have considered the effects of such processing conditions on the physical and mechanical anisotropy achieved. The aim of this study was to demonstrate the tunability of the structure and mechanical anisotropy of foams prepared using a variety of different gas foaming conditions. Porous poly(D,L lactic acid) foams were prepared by the systematic adjustment of processing conditions, namely pressure, temperature and venting time, resulting in an extensive range of scaffold morphologies. Characterization of sample anisotropy was achieved by mechanical evaluation of foam specimens both longitudinal and transverse to the foaming direction. The obtained mechanical properties demonstrated a strong dependence of the processing conditions on mechanical anisotropy and performance. Furthermore, results indicate that factors other than pore geometry may be necessary to define the mechanical behavior of the foam specimens. The favorable compressive moduli, coupled with large degrees of anisotropy, suggests these foams may have suitable application as scaffolds for bone tissue engineering.
组织支架的设计和可调节性，如孔径和几何形状，对于工程化组织替代物的成功至关重要。此外，组织支架的机械性质应该与感兴趣的组织相似；因此，泡沫机械性能的可调节性是理想的。近年来，使用超临界二氧化碳作为发泡剂制备聚合物泡沫已成为一种有前途的制备多孔支架的技术。虽然许多小组已经报道了通过气体发泡技术来调整支架形态，但很少考虑到这些处理条件对所获得的物理和机械各向异性的影响。本研究的目的是展示使用各种不同气体发泡条件制备的泡沫的结构和机械各向异性的可调节性。通过系统地调整处理条件，即压力、温度和通气时间，制备了多孔聚(D,L-乳酸)泡沫，从而获得了广泛的支架形态。通过沿发泡方向纵向和横向机械评估泡沫样品，实现了样品各向异性的表征。所获得的机械性能表明，机械各向异性和性能强烈依赖于处理条件。此外，结果表明，除了孔几何形状之外，可能还需要其他因素来定义泡沫样品的机械行为。有利的压缩模量，加上大的各向异性度，表明这些泡沫可能适合用作骨组织工程的支架。
