Wen Chien-Hui, Hsu Shun-Chieh, Hsu Shan-Hui, Chang Shu-Wei
Department of Civil Engineering, National Taiwan University, Taipei, Taiwan.
Inistitute of Polymer Science and Engineering, National Taiwan University, Taipei, Taiwan.
Comput Struct Biotechnol J. 2018 Dec 31;17:110-117. doi: 10.1016/j.csbj.2018.12.007. eCollection 2019.
Biodegradable hydrogels have become promising materials for many biological applications in the past years. Recently, novel waterborne biodegradable polyurethane (WDPU) nanoparticles have been synthesized by a green water-based process, and serve as fundamental building blocks to form materials with great biocompatibility, biodegradability, and mechanical properties. However, the molecular structures and mechanisms of the WDPU nanoparticles and the relationship between the chemical compositions of the polymer segments and the material properties of the biodegradable hydrogels at macro-scale are still not well understood. In this study, we explore the fundamental mechanisms of WDPU nanoparticles through a full atomistic simulation approach to understand how the chemical compositions at the molecular level affect the molecular structures and material properties of WDPU nanoparticles. Specifically, we compare two WDPUs, i.e. PCL75LL25 and PCL75DL25, of the same hard segment composition and very similar soft segment composition [75% poly(e-caprolatone) and 25% polylactide], except the lactide in the former is L-form and in the latter is D,L-form. Our results show that the material properties of the biodegradable hydrogel can be designed by tuning the chemical compositions of the polymer segments. We find that the PCL75DL25 and PCL75LL25 have distinct molecular structures and physical crosslinks within the nanoparticles. The molecular structure of WDPU with PDLLA as soft segments is more extended, leading to more physical crosslinks between PCL segments. This study provide fundamental insights into the molecular structures and mechanisms of WDPU nanoparticles and help enabling the design of material properties of biocompatible hydrogel.
在过去几年中，可生物降解水凝胶已成为许多生物应用中颇具前景的材料。最近，通过绿色水基工艺合成了新型水性可生物降解聚氨酯（WDPU）纳米颗粒，这些纳米颗粒作为基本构建单元，可形成具有良好生物相容性、生物降解性和机械性能的材料。然而，WDPU纳米颗粒的分子结构和机制，以及聚合物链段的化学组成与宏观尺度上可生物降解水凝胶材料性能之间的关系仍未得到很好的理解。在本研究中，我们通过全原子模拟方法探索WDPU纳米颗粒的基本机制，以了解分子水平上的化学组成如何影响WDPU纳米颗粒的分子结构和材料性能。具体而言，我们比较了两种WDPU，即PCL75LL25和PCL75DL25，它们具有相同的硬段组成和非常相似的软段组成[75%聚（ε-己内酯）和25%聚丙交酯]，只是前者中的丙交酯为L型，后者中的丙交酯为D,L型。我们的结果表明，可通过调节聚合物链段的化学组成来设计可生物降解水凝胶的材料性能。我们发现PCL75DL25和PCL75LL25在纳米颗粒内具有不同的分子结构和物理交联。以聚（D,L-丙交酯-co-乙交酯）作为软段的WDPU的分子结构更加伸展，导致PCL链段之间形成更多的物理交联。本研究为WDPU纳米颗粒的分子结构和机制提供了基本见解，并有助于设计生物相容性水凝胶的材料性能。
