School of Electronics and Control Engineering , Chang'an University , Middle-Section of Nan'er Huan Road , Xi'an 710064 , P. R. China.
ACS Appl Mater Interfaces. 2018 Nov 21;10(46):40228-40237. doi: 10.1021/acsami.8b12597. Epub 2018 Nov 6.
Microfiber modules with controllable lengths emerged as novel biomimetic platforms and are significant for many tissue engineering applications. However, accurately controlling the length of microfibers on the scale of millimeter or even micrometer still remains challenging. Here, a novel and scalable strategy to generate microfiber modules with precisely tunable lengths ranging from 100 to 3500 μm via an alternating current (AC) electric field is presented. To control the microfiber length, double-emulsion droplets containing a chelating agent (sodium citrate) as a spacing node are first uniformly embedded in the microfibers in a controllable spatial arrangement. This process is precisely tuned by adjusting the flow rates, thus, tailoring the resulting multicompartmental microfiber structure. Next, an AC voltage signal is used to trigger the electric field-induced cutting process, where the time-averaged electrical force acting on the induced bipolar charge from the Maxwell-Wagner structural polarization mechanism breaks the stress balance at the interfaces, rupturing the double-emulsion droplets, and resulting in the burst release of the encapsulated chelating agents into the hydrogel cavity. The outer hydrogel shell is quickly dissolved by a chemical reaction, cutting the long fiber into a series of microfiber units of given length. Furthermore, adding magnetic nanoparticles endows magnetic functionality with these microfiber modules, which are allowed to serve as micromotors and building blocks. This electro-induced cutting method provides a facile strategy for the fabrication of microfibers with desired lengths, showing considerable promise for various chemical and biological applications.
具有可控长度的微纤维模块作为新型仿生平台，对许多组织工程应用具有重要意义。然而，在毫米甚至微米的尺度上精确控制微纤维的长度仍然具有挑战性。在这里，我们提出了一种新颖的、可扩展的策略，通过交流（AC）电场来生成具有精确可调长度（从 100 到 3500μm）的微纤维模块。为了控制微纤维的长度，首先在微纤维中均匀嵌入含有螯合剂（柠檬酸钠）作为间隔节点的双乳液液滴，以可控的空间排列方式。通过调整流速，可以精确地调整微纤维的长度，从而定制出多腔室微纤维结构。接下来，利用交流电压信号触发电场诱导的切割过程，其中麦克斯韦-沃格纳结构极化机制引起的诱导双极电荷的平均电场力打破界面处的应力平衡，使双乳液液滴破裂，并导致包裹的螯合剂释放到水凝胶腔中。外水凝胶壳迅速通过化学反应溶解，将长纤维切成一系列给定长度的微纤维单元。此外，添加磁性纳米粒子赋予这些微纤维模块磁性功能，使其能够作为微马达和构建块。这种电诱导切割方法为制备具有所需长度的微纤维提供了一种简便的策略，在各种化学和生物学应用中具有很大的应用前景。
