Complex Materials, Department of Materials, Vladimir-Prelog-Weg 5, ETH Zurich, 8093 Zurich, Switzerland.
Soft Matter. 2017 Mar 1;13(9):1794-1803. doi: 10.1039/c6sm02682f.
3D printing via direct ink writing (DIW) is a versatile additive manufacturing approach applicable to a variety of materials ranging from ceramics over composites to hydrogels. Due to the mild processing conditions compared to other additive manufacturing methods, DIW enables the incorporation of sensitive compounds such as proteins or drugs into the printed structure. Although emulsified oil-in-water systems are commonly used vehicles for such compounds in biomedical, pharmaceutical, and cosmetic applications, printing of such emulsions into architectured soft materials has not been fully exploited and would open new possibilities for the controlled delivery of sensitive compounds. Here, we 3D print concentrated emulsions into soft materials, whose multiphase architecture allows for site-specific incorporation of both hydrophobic and hydrophilic compounds into the same structure. As a model ink, concentrated emulsions stabilized by chitosan-modified silica nanoparticles are studied, because they are sufficiently stable against coalescence during the centrifugation step needed to create a bridging network of droplets. The resulting ink is ideal for 3D printing as it displays high yield stress, storage modulus and elastic recovery, through the formation of networks of droplets as well as of gelled silica nanoparticles in the presence of chitosan. To demonstrate possible architectures, we print biocompatible soft materials with tunable hierarchical porosity containing an encapsulated hydrophobic compound positioned in specific locations of the structure. The proposed emulsion-based ink system offers great flexibility in terms of 3D shaping and local compositional control, and can potentially help address current challenges involving the delivery of incompatible compounds in biomedical applications.
通过直接墨水书写（DIW）进行 3D 打印是一种多功能的增材制造方法，适用于从陶瓷到复合材料再到水凝胶等各种材料。与其他增材制造方法相比，由于其处理条件较为温和，DIW 能够将敏感化合物（如蛋白质或药物）纳入打印结构中。虽然乳化的油包水体系通常是生物医学、制药和化妆品应用中此类化合物的常用载体，但将此类乳液打印成具有结构的软材料尚未得到充分利用，这将为敏感化合物的控制释放开辟新的可能性。在这里，我们将浓缩乳液 3D 打印成软材料，其多相结构允许将疏水性和亲水性化合物同时掺入到同一结构中。作为模型墨水，研究了由壳聚糖改性的二氧化硅纳米粒子稳定的浓缩乳液，因为它们在需要创建液滴桥接网络的离心步骤中足够稳定，不易发生聚并。由于在壳聚糖存在下形成液滴网络以及凝胶化的二氧化硅纳米粒子，所得墨水非常适合 3D 打印，因为它显示出高屈服应力、储能模量和弹性恢复。为了演示可能的结构，我们打印了具有可调节的分层孔隙度的生物相容性软材料，其中包含封装在结构特定位置的疏水性化合物。基于乳液的油墨系统在 3D 成型和局部组成控制方面具有很大的灵活性，并且有可能有助于解决生物医学应用中涉及不相容化合物输送的当前挑战。
