以分子動力模擬探討水性生物可降解聚氨酯的成膠機制以及氧氣擴散性質

Abstract

如今，生物降解水膠已成為許多生物應用的熱門材料。它們不僅具有與天然軟組織相似的機械性能，而且還具有在人體中使用後被降解的功能。最近，一種新型水性生物可降解聚氨酯已經被合成並顯示出在生物醫學應用中具有很大的潛力。此材料具有優良的生物相容性，生物降解能力和機械性質。且已被作為3D列印墨水，並成功製造出神經細胞培養的載體。然而，可降解聚氨酯的成膠機制以及軟鏈段與生物降解聚氨酯性質之間的關係在實驗上尚未明確。 本研究旨在透過原子尺度分子動力模擬探討生物可降解聚氨酯的成膠機制。為了瞭解成膠行為，我們模擬了3種以PCL和PLA為主要軟鏈成分之聚氨酯模型。並藉由分析成膠過程不同階段的結構與性質差異性，包括分子間氫鍵、與水間氫鍵、頭尾端距與表面個數，探討其中成膠的關聯性，並發現聚氨酯奈米粒子間的堆積作用，會是影響成膠的關鍵。 本研究也利用模擬探討氧氣在生物可降解聚氨酯水膠內部的擴散行為。為了瞭解水膠之氧氣擴散，我們透過模擬不同的生物可降解聚氨酯水膠之網狀結構模型。並分析了氧氣在模型中的運動軌跡以及在運動時受到水分子與聚氨酯高分子的影響。並發現氧氣在水膠中擴散時，容易與聚氨酯分子產生吸附，降低擴散速率。

Biodegradable hydrogels have become popular materials for many biological applications. They not only exhibit similar mechanical properties as natural soft tissues but also have the ability to be degraded in human body after their useful lifetime. Recently, a novel waterborne biodegradable polyurethane(WDPU) has been synthesized and shown to have great potential in biomedical applications. It is synthesized by a green water-based process, and has great biocompatibility, biodegradability, and mechanical properties. Furthermore, it has been used as a 3D printing ink recently to create a neural cell culture carrier successfully. However, the gelation mechanisms of WDPU and the relationship between the soft segments of the polymer and the material properties of WDPU at macro-scale are still not clear. In this study, we aim to explore the gelation mechanisms of WDPU through a full atomistic simulation approach. To investigate gel formation, we build three different WDPU models with PLA and PCL as soft segments, and analyze differences in structure and properties at different stage of gelation process. Also, we use simulations to investigate the diffusion behavior of oxygen in WDPU hydrogels. In order to understand the oxygen diffusion of WDPU hydrogel, we build the network structure models of different WDPU hydrogels. We analyze the trajectory of oxygen in the model and the movement of oxygen in WDPU. We found that when oxygen diffuses in the hydrogel, it easily adsorbs with the polyurethane molecules and reduces the diffusion rate.