Song Chaobo, Luo Yunhan, Liu Yankai, Li Shuang, Xi Zhenhao, Zhao Ling, Cen Lian, Lu Eryi
Shanghai Key Laboratory of Multiphase Materials Chemical Engineering, School of Chemical engineering, East China University of Science and Technology, Shanghai 200237, China.
School of Medicine, Shanghai Jiaotong University, Shanghai 200127, China.
Polymers (Basel). 2020 Apr 2;12(4):780. doi: 10.3390/polym12040780.
Polycaprolactone (PCL) scaffolds have recently been developed via efficient and green supercritical carbon dioxide (scCO) melt-state foaming. However, previously reported gas-foamed scaffolds sometimes showed insufficient interconnectivity or pore size for tissue engineering. In this study, we have correlated the thermal and rheological properties of PCL scaffolds with their porous morphology by studying four foamed samples with varied molecular weight (MW), and particularly aimed to clarify the required properties for the fabrication of scaffolds with favorable interconnected macropores. DSC and rheological tests indicate that samples show a delayed crystallization and enhanced complex viscosity with the increasing of MW. After foaming, scaffolds (27 kDa in weight-average molecular weight) show a favorable morphology (pore size = 70-180 μm, porosity = 90% and interconnectivity = 96%), where the lowest melt strength favors the generation of interconnected macropore, and the most rapid crystallization provides proper foamability. The scaffolds (27 kDa) also possess the highest Young's modulus. More importantly, owing to the sufficient room and favorable material transportation provided by highly interconnected macropores, cells onto the optimized scaffolds (27 kDa) perform vigorous proliferation and superior adhesion and ingrowth, indicating its potential for regeneration applications. Furthermore, our findings provide new insights into the morphological control of porous scaffolds fabricated by scCO foaming, and are highly relevant to a broader community that is focusing on polymer foaming.
聚己内酯（PCL）支架最近通过高效且绿色的超临界二氧化碳（scCO₂）熔体状态发泡法得以开发。然而，先前报道的气体发泡支架有时在组织工程所需的互连性或孔径方面表现欠佳。在本研究中，我们通过研究四种分子量（MW）不同的发泡样品，将PCL支架的热性能和流变性能与其多孔形态相关联，特别旨在阐明制造具有良好互连大孔的支架所需的性能。差示扫描量热法（DSC）和流变测试表明，随着分子量的增加，样品表现出结晶延迟和复数粘度增强。发泡后，支架（重均分子量为27 kDa）呈现出良好的形态（孔径 = 70 - 180μm，孔隙率 = 90%，互连性 = 96%），其中最低的熔体强度有利于互连大孔的生成，而最快的结晶速度提供了适当的发泡性。该支架（27 kDa）还具有最高的杨氏模量。更重要的是，由于高度互连的大孔提供了充足的空间和良好的物质传输，接种在优化后的支架（27 kDa）上的细胞表现出旺盛的增殖以及优异的粘附和向内生长能力，表明其在再生应用方面的潜力。此外，我们的研究结果为通过scCO₂发泡制造的多孔支架的形态控制提供了新的见解，并且与更广泛关注聚合物发泡的群体高度相关。
