Weems Andrew C, Easley Alexandra, Roach Sydney Reese, Maitland Duncan J
Department of Biomedical Engineering, Texas A&M University, College Station, Texas 77840, United States.
ACS Appl Bio Mater. 2019 Jan 22;2(1):454-463. doi: 10.1021/acsabm.8b00650. Epub 2018 Dec 17.
Minimally invasive medical devices are of great interest, with shape memory polymers (SMPs) representing one such possibility for producing these devices. Previous work with low density, highly porous SMPs has demonstrated oxidative degradation, while attempts to incorporate hydrolytic degradation have resulted in rapidly decreasing glass transition temperature (T ), ultimately preventing strain fixity of the materials at clinically relevant temperatures. Through esterification of the amino alcohol triethanolamine, an alcohol containing network was synthesized and incorporated into SMPs. These ester networks were used to control the bulk morphology of the SMP, with the T remaining above 37 °C when 50% of the alcohol was contributed by the ester network. This methodology also yielded SMPs that could degrade through both hydrolysis and oxidation; by oxidation, the SMPs degrade at a similar rate as the control materials (0.2%/day mass) for the first 30 days, at which point the rate changes to 3.5%/day until the samples become too fragile to examine at 80 days. By comparison, control materials have lost approximately 30% of mass by 140 days, at a constant rate of degradation, demonstrating that the ester SMPs are a promising material system for producing more rapidly degradable, soft, porous biomaterials.
微创医疗器械备受关注，形状记忆聚合物（SMPs）是制造这类器械的一种可能材料。先前对低密度、高孔隙率SMPs的研究表明其存在氧化降解，而尝试引入水解降解则导致玻璃化转变温度（T ）迅速降低，最终在临床相关温度下无法实现材料的应变固定。通过对氨基醇三乙醇胺进行酯化反应，合成了一种含醇网络并将其引入SMPs中。这些酯网络用于控制SMP的整体形态，当酯网络贡献50%的醇时，T 保持在37℃以上。该方法还制备出了可通过水解和氧化两种方式降解的SMPs；通过氧化，SMPs在前30天的降解速率与对照材料相似（0.2%/天质量），此后降解速率变为3.5%/天，直至80天时样品变得过于脆弱无法检测。相比之下，对照材料在140天时以恒定降解速率损失了约30%的质量，这表明酯基SMPs是一种有前景的材料体系，可用于制造降解更快、柔软且多孔的生物材料。
