Department of Materials Science and Engineering , University of Illinois at Urbana-Champaign , 1304 West Green Street , Urbana , Illinois 61801 , United States.
Department of Chemical and Biomolecular Engineering , University of Illinois at Urbana-Champaign , 600 South Mathews Avenue , Urbana , Illinois 61801 , United States.
Langmuir. 2019 Aug 20;35(33):10947-10957. doi: 10.1021/acs.langmuir.9b01360. Epub 2019 Aug 7.
Bioinspired materials have been developed with the aim of harnessing natural self-assembly for precisely engineered functionality. Microfluidics is poised to play a key role in the directed assembly of advanced materials with ordered nano and mesoscale features. More importantly, there is a strong need for understanding the kinetics of continuous assembly processes. In this work, we describe a continuous microfluidic system for the assembly and alignment of synthetic oligopeptides with π-conjugated cores using a three-dimensional (3D) flow focusing of inlet reactant streams. This system facilitates in situ confocal fluorescence microscopy and in situ fluorescence lifetime imaging microscopy (FLIM), which can be used in unprecedented capacity to characterize the integrity of peptides during the assembly process. To achieve continuous assembly, we integrate chevron patterns in the ceiling and floor of the microdevice to generate a 3D-focused sheath flow of the reactant peptide. Consequently, the peptide stream is directed toward an acidic triggering stream in a cross-slot geometry which mediates assembly into higher-order fiber-like structures. Using this approach, the focused peptide stream is assembled using a planar extensional flow, which ensures high degrees of microstructural alignment within the assembled material. We demonstrate the efficacy of this approach using three different synthetic oligopeptides, and in all cases, we observe the efficient and continuous assembly of oligopeptides. In addition, finite element simulations are used to guide device design and to validate 3D focusing. Overall, this approach presents an efficient and effective method for the continuous assembly and alignment of ordered materials using microfluidics.
生物灵感材料的开发旨在利用自然自组装来实现精确设计的功能。微流控技术有望在先进材料的定向组装中发挥关键作用，这些材料具有有序的纳米和介观特征。更重要的是，人们强烈需要了解连续组装过程的动力学。在这项工作中，我们描述了一种连续微流控系统，用于使用三维（3D）入口反应物流的流聚焦来组装和对齐具有π-共轭核的合成寡肽。该系统有利于进行原位共聚焦荧光显微镜和原位荧光寿命成像显微镜（FLIM），这可以以前所未有的能力来表征肽在组装过程中的完整性。为了实现连续组装，我们在微器件的天花板和地板上集成了雪佛龙图案，以产生反应物肽的 3D 聚焦鞘流。因此，肽流被引导到交叉槽几何形状中的酸性触发流中，这介导了更高阶纤维状结构的组装。使用这种方法，聚焦肽流使用平面拉伸流进行组装，这确保了组装材料内的微观结构高度对齐。我们使用三种不同的合成寡肽证明了这种方法的有效性，在所有情况下，我们都观察到寡肽的高效连续组装。此外，有限元模拟用于指导器件设计并验证 3D 聚焦。总的来说，这种方法为使用微流控技术连续组装和对齐有序材料提供了一种高效有效的方法。
