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.

中文翻译：

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选择性激光烧结聚己内酯晶格支架的原位重熔和重新凝固处理，可改善灯丝质量和机械性能。

选择性激光烧结（SLS）是一种有前途的增材制造技术，无需额外的支持即可生产具有高度多孔结构的可生物降解组织工程支架。然而，SLS工艺固有地导致部分熔融的微结构，这显着损害了所得支架的机械性能，从而潜在地用于组织工程和再生医学中。在这里，开发了一种新的后处理策略，以使SLS制成的聚己内酯（PCL）支架具有致密的形态和增强的机械性能，方法是将它们嵌入致密的NaCl微粒中以进行原位重熔和重新固化。研究了重熔温度和停留时间对SLS制丝的微观结构的影响。结果表明，进行充分处理的最低重熔温度和停留时间分别为65°C和5 min，并且SLS制成的长丝尺寸从683.3±28.0μm减小至601.6±17.4μm。该方法在治疗三维（3D）PCL晶格支架方面也非常有效，该支架在后处理后显示出改善的长丝质量和机械性能。经处理的PCL支架的初始压缩模量和强度分别为3027.8±204.2 kPa和208.8±14.5 kPa，可以在体内植入24周后保持其原始形状。发现大量新近生长的组织沿着PCL细丝逐渐渗透到多孔区域。尽管发生降解，但是稳定地维持了植入的构建体的机械性能。