Kishan Alysha P, Wilems Thomas, Mohiuddin Sahar, Cosgriff-Hernandez Elizabeth M
Department of Biomedical Engineering, Texas A&M University, 5045 Emerging Technologies Building, 3120 TAMU, College Station, Texas 77843-3120, United States.
Department of Biomedical Engineering, University of Texas, 107 W. Dean Keaton, 1 University Station, Austin, Texas 78712, United States.
ACS Biomater Sci Eng. 2017 Dec 11;3(12):3493-3502. doi: 10.1021/acsbiomaterials.7b00512. Epub 2017 Nov 1.
The highly tunable mechanical properties and resilience of polyurethanes make them promising candidates for tissue engineering applications. Biodegradability is conferred by incorporation of hydrolytically or enzymatically cleavable moieties into the polyurethane structure. A common choice for the biodegradable soft segment is a poly(ether ester) triblock copolymer synthesized by ring opening polymerization of the polyester from a polyether macroinitiator. Herein, we describe a new "plug-and-play" approach for triblock synthesis based on urethane block coupling that enables finer control of block lengths and ease of segmental tuning. The inclusion of urethane linkages in the soft segment was also hypothesized to promote hydrogen bonding between the segments with an associated increase in modulus, tensile strength, and ultimate elongation. Hard segment content of the biodegradable polyurethane urea was varied to demonstrate the tunable tensile properties and degradation rate. As expected, increasing hard segment content led to large increases in initial secant modulus and tensile strength. A corollary decrease in ultimate elongation, elastic recovery, and degradation rate was also observed with increasing hard segment content. Finally, cytocompatibility and hydrolytic degradation of electrospun polyurethane meshes were evaluated to establish the potential use of these biodegradable matrixes as tissue engineering scaffolds. All of the polyurethane formulations displayed comparable cytocompatibilty to tissue culture plastic controls and hydrolytic chain scission of the polyester soft segment. Overall, this synthetic approach provides a platform to produce biodegradable polyurethane ureas with enhanced control over segmental chemistry, mechanical properties, and degradation rate.
聚氨酯具有高度可调节的机械性能和弹性，使其成为组织工程应用的理想候选材料。通过将可水解或可酶解的部分引入聚氨酯结构中可赋予其生物降解性。可生物降解软段的常见选择是由聚醚大分子引发剂通过聚酯的开环聚合合成的聚（醚酯）三嵌段共聚物。在此，我们描述了一种基于聚氨酯嵌段偶联的三嵌段合成新的“即插即用”方法，该方法能够更精细地控制嵌段长度并便于进行分段调节。还假设在软段中包含聚氨酯键会促进各段之间的氢键形成，从而使模量、拉伸强度和极限伸长率相应增加。改变可生物降解聚氨酯脲的硬段含量以证明其可调节的拉伸性能和降解速率。正如预期的那样，硬段含量的增加导致初始割线模量和拉伸强度大幅增加。随着硬段含量的增加，还观察到极限伸长率、弹性回复率和降解速率相应降低。最后，评估了电纺聚氨酯网的细胞相容性和水解降解性能，以确定这些可生物降解基质作为组织工程支架的潜在用途。所有聚氨酯配方与组织培养塑料对照相比均表现出相当的细胞相容性以及聚酯软段的水解断链。总体而言，这种合成方法提供了一个平台，可用于生产对分段化学、机械性能和降解速率具有更强控制能力的可生物降解聚氨酯脲。
