Biomedical Engineering Department, McGill University and Genome Quebec Innovation Centre, McGill University, Montréal, Canada.
Biomed Microdevices. 2014 Jun;16(3):387-95. doi: 10.1007/s10544-014-9842-8.
Cell distribution and nutrient supply in 3D cell-laden hydrogel scaffolds are critical and should mimic the in vivo cellular environment, but been difficult to control with conventional fabrication methods. Here, we present a microfluidic direct writer (MFDW) to construct 3D cell-laden hydrogel structures with openings permitting media exchange. The MFDW comprises a monolithic microfluidic head, which delivers coaxial streams of cell-laden sodium alginate and calcium chloride solutions to form hydrogel fibers. Fiber diameter is controlled by adjusting the ratio of the volumetric flow rates. The MFDW head is mounted on a motorized stage, which is automatically controlled and moves at a speed synchronized with the speed of fiber fabrication. Head geometry, flow rates, and viscosity of the writing solutions were optimized to prevent the occurrence of curling and bulging. For continuous use, a highly reliable process is needed, which was accomplished with the integration of a declogging conduit supplying a solvent to dissolve the clogging gel. The MFDW was used for layer-by-layer fabrication of simple 3D structures with encapsulated cells. Assembly of 3D structures with distinct fibers is demonstrated by alternatively delivering two different alginate gel solutions. The MFDW head can be built rapidly and easily, and will allow 3D constructs for tissue engineering to be fabricated with multiple hydrogels and cell types.
三维细胞水凝胶支架中的细胞分布和营养供应至关重要，应模拟体内细胞环境，但这很难用传统的制造方法来控制。在这里，我们提出了一种微流控直接写入器（MFDW），用于构建具有允许介质交换的开口的 3D 细胞水凝胶结构。MFDW 包括一个整体式微流控头，它输送载细胞的海藻酸钠和氯化钙溶液的同轴流，以形成水凝胶纤维。通过调整体积流量比来控制纤维直径。MFDW 头安装在一个电动台上，该台自动控制并以与纤维制造速度同步的速度移动。优化了头几何形状、流速和写入溶液的粘度，以防止卷曲和凸起的发生。为了连续使用，需要一个高度可靠的过程，这是通过集成一个疏通管道来完成的，该管道提供溶剂以溶解堵塞的凝胶。MFDW 用于封装细胞的简单 3D 结构的逐层制造。通过交替输送两种不同的藻酸盐凝胶溶液来演示具有不同纤维的 3D 结构的组装。MFDW 头可以快速、轻松地构建，并且将允许使用多种水凝胶和细胞类型来制造用于组织工程的 3D 结构。
