Russias J, Saiz E, Deville S, Gryn K, Liu G, Nalla R K, Tomsia A P
Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
J Biomed Mater Res A. 2007 Nov;83(2):434-45. doi: 10.1002/jbm.a.31237.
A key issue for the fabrication of scaffolds for tissue engineering is the development of processing techniques flexible enough to produce materials with a wide spectrum of solubility (bioresorption rates) and mechanical properties matching those of calcified tissues. These techniques must also have the capability of generating adequate porosity to further serve as a framework for cell penetration, new bone formation, and subsequent remodeling. In this study we show how hybrid organic/inorganic scaffolds with controlled microstructures can be built using robotic assisted deposition at room temperature. Polylactide or polycaprolactone scaffolds with pore sizes ranging between 200-500 microm and hydroxyapatite contents up to 70 wt % were fabricated. Compressive tests revealed an anisotropic behavior of the scaffolds, strongly dependant on their chemical composition. The inclusion of an inorganic component increased their stiffness but they were not brittle and could be easily machined even for ceramic contents up to 70 wt %. The mechanical properties of hybrid scaffolds did not degrade significantly after 20 days in simulated body fluid. However, the stiffness of pure polylactide scaffolds increased drastically due to polymer densification. Scaffolds containing bioactive glasses were also printed. After 20 days in simulated body fluid they developed an apatite layer on their surface.
组织工程支架制造中的一个关键问题是开发足够灵活的加工技术，以生产具有广泛溶解度（生物吸收速率）和与钙化组织相匹配的机械性能的材料。这些技术还必须具备产生足够孔隙率的能力，以进一步作为细胞渗透、新骨形成和后续重塑的框架。在本研究中，我们展示了如何在室温下使用机器人辅助沉积构建具有可控微观结构的有机/无机混合支架。制备了孔径在200 - 500微米之间、羟基磷灰石含量高达70 wt%的聚乳酸或聚己内酯支架。压缩试验揭示了支架的各向异性行为，这在很大程度上取决于它们的化学成分。无机成分的加入提高了它们的刚度，但它们并不脆，即使陶瓷含量高达70 wt%也能很容易地进行加工。混合支架在模拟体液中放置20天后，其机械性能没有明显下降。然而，由于聚合物致密化，纯聚乳酸支架的刚度急剧增加。还打印了含有生物活性玻璃的支架。在模拟体液中放置20天后，它们的表面形成了一层磷灰石层。
