State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, Xi'an 710049, People's Republic of China. Rapid manufacturing research center of Shaanxi Province, Xi'an Jiaotong University, Xi'an 710049, People's Republic of China.
Biofabrication. 2020 May 15;12(3):035012. doi: 10.1088/1758-5090/ab860e.
Selective laser sintering (SLS) is a promising additive manufacturing technique that produces biodegradable tissue-engineered scaffolds with highly porous architectures without additional supporting. However, SLS process inherently results in partially melted microstructures which significantly impair the mechanical properties of the resultant scaffolds for potential applications in tissue engineering and regenerative medicine. Here, a novel post-treatment strategy was developed to endow the SLS-fabricated polycaprolactone (PCL) scaffolds with dense morphology and enhanced mechanical properties by embedding them in dense NaCl microparticles for in-situ re-melting and re-solidification. The effects of re-melting temperature and dwelling time on the microstructures of the SLS-fabricated filaments were studied. The results demonstrated that the minimum requirements of re-melting temperature and dwelling time for sufficient treatment were 65 °C and 5 min respectively and the size of the SLS-fabricated filaments was reduced from 683.3 ± 28.0 μm to 601.6 ± 17.4 μm. This method was also highly effective in treating three-dimensional (3D) PCL lattice scaffolds, which showed improved filament quality and mechanical properties after post-treatment. The treated PCL scaffolds with an initial compressive modulus and strength of 3027.8 ± 204.2 kPa and 208.8 ± 14.5 kPa can maintain their original shapes after implantation in vivo for 24 weeks. Extensive newly-grown tissues were found to gradually penetrate into the porous regions along the PCL filaments. Although degradation occurred, the mechanical properties of the implanted constructs stably maintained. The presented method provides an innovative, green and general post-treatment strategy to improve both the filament quality and mechanical properties of SLS-fabricated PCL scaffolds for various tissue engineering applications.
选择性激光烧结（SLS）是一种很有前途的增材制造技术，它可以生产具有高度多孔结构的可生物降解组织工程支架，而无需额外的支撑。然而，SLS 工艺本质上会导致部分熔化的微观结构，这会显著降低支架的机械性能，使其无法应用于组织工程和再生医学。在这里，我们开发了一种新的后处理策略，通过将 SLS 制造的聚己内酯（PCL）支架嵌入致密的 NaCl 微颗粒中，实现原位再熔化和再凝固，从而为 SLS 制造的支架赋予致密的形态和增强的机械性能。研究了再熔化温度和停留时间对 SLS 制造的纤维微观结构的影响。结果表明，充分处理所需的再熔化温度和停留时间的最小要求分别为 65°C 和 5 分钟，SLS 制造的纤维尺寸从 683.3±28.0μm 减小到 601.6±17.4μm。这种方法对三维（3D）PCL 晶格支架也非常有效，后处理后支架的纤维质量和机械性能得到了改善。处理后的 PCL 支架初始压缩模量和强度分别为 3027.8±204.2kPa 和 208.8±14.5kPa，在体内植入 24 周后仍能保持其原有形状。大量新生长的组织逐渐沿着 PCL 纤维渗透到多孔区域。尽管发生了降解，但植入物的机械性能仍稳定保持。所提出的方法为改善 SLS 制造的 PCL 支架的纤维质量和机械性能提供了一种创新的、绿色的、通用的后处理策略，适用于各种组织工程应用。
