The Dissolvable Alginate Fiber Network Produced Via the Immersed Microfluidic Spinning

Abstract

Pore size and pore interconnectivity that characterize the topology of the vascular networks in tissue constructs are critical to healthy cell behavior and tissue formation. While scaffolds with hollow channel structures (that precede vascularization of tissue engineering constructs) have gained significant attention, still creating the hollow channel networks within various cellular matrices such as cell-laden hydrogels, remain a slow process limited by the speed of material extrusion of 3D printing techniques for the deposition of sacrificial fibers. To address the issue of low throughput for sacrificial fiber production and placement, we propose to utilize the micromanufacturing technique of the immersed microfluidic spinning. This study discusses the optimization of the topology of the sacrificial calcium alginate microfibers as a function of alginate concentration and the gauge of the needle used in the immersed fluidic spinning. An important parameter of the fabricated fiber network is the size of the loops produced via the immersed fluidic spinning. The nutrients should diffuse from the fluidic channel to the center of the loop. We demonstrate that the loops with radii between approximately 1600 and 3200 μm can be produced with needle of 30 gauge for alginate concentrations between 1% and 8%. Fiber diameters are also characterized as a function of needle gauge and alginate concentration. We demonstrate the creation of a hollow channel in a Methacrylate gelatin (GelMA) sample by dissolving the alginate fibers produced via the immersed fluidic spinning method. Finally, viability of the fibroblast cells in GelMA is qualitatively studied as a function of the distance of the cells from the outside boundary of the gel (where the cell media is located). As expected, the cell viability falls as the distance from the outer boundary of the gel increases.