Department of Mechanical and Aerospace Engineering, University of Missouri, Columbia 65211, USA.
Department of Surgery, School of Medicine, University of Missouri, Columbia 65211, USA.
Biomater Adv. 2023 Oct;153:213575. doi: 10.1016/j.bioadv.2023.213575. Epub 2023 Aug 1.
Conventional implants tend to have significant limitations, as they are one-size-fits-all, require monitoring, and have the potential for immune rejection. However, 4D Printing presents a method to manufacture highly personalized, shape-changing, minimally invasive biomedical implants. Shape memory polymers (SMPs) with a glass transition temperature (T) between room and body temperature (20-38 °C) are particularly desirable for this purpose, as they can be deformed to a temporary shape before implantation, then undergo a shape change within the body. Commonly used SMPs possess either an undesirable T or lack the biocompatibility or mechanical properties necessary to match soft biological tissues. In this work, Poly(glycerol dodecanoate) acrylate (PGDA) with engineered pores is introduced to solve these issues. Pores are induced by porogen leaching, where microparticles are mixed with the printing ink and then are dissolved in water after 3D printing, creating a hierarchically porous texture to improve biological activity. With this method, highly complex shapes were printed, including overhanging structures, tilted structures, and a "3DBenchy". The porous SMP has a T of 35.6 °C and a Young's Modulus between 0.31 and 1.22 MPa, comparable to soft tissues. A one-way shape memory effect (SME) with shape fixity and recovery ratios exceeding 98 % was also demonstrated. Cultured cells had a survival rate exceeding 90 %, demonstrating cytocompatibility. This novel method creates hierarchically porous shape memory scaffolds with an optimal T for reducing the invasiveness of implantation and allows for precise control over elastic modulus, porosity, structure, and transition temperature.
传统植入物往往存在显著的局限性，因为它们是一刀切的，需要监测，并且存在免疫排斥的可能性。然而，4D 打印提供了一种制造高度个性化、形状可变化、微创生物医学植入物的方法。玻璃化转变温度（T）在室温到体温（20-38°C）之间的形状记忆聚合物（SMP）特别适用于此目的，因为它们可以在植入前被变形为临时形状，然后在体内发生形状变化。通常使用的 SMP 要么具有不理想的 T，要么缺乏与软生物组织相匹配的生物相容性或机械性能。在这项工作中，引入了具有工程孔的聚（十二烷二酸甘油酯）丙烯酸酯（PGDA）来解决这些问题。通过致孔剂溶出诱导孔，将微球与打印墨水混合，然后在 3D 打印后在水中溶解，从而形成分级多孔结构，以提高生物活性。通过这种方法，可以打印出非常复杂的形状，包括悬垂结构、倾斜结构和“3DBenchy”。多孔 SMP 的 T 为 35.6°C，杨氏模量在 0.31 到 1.22MPa 之间，与软组织相当。还证明了具有超过 98%的形状固定率和恢复率的单向形状记忆效应（SME）。培养细胞的存活率超过 90%，表现出细胞相容性。这种新方法创建了具有最佳 T 的分级多孔形状记忆支架，可降低植入物的侵入性，并可精确控制弹性模量、孔隙率、结构和转变温度。
