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Traditional approaches in scaffolds fabrication have some limitations because cells are seeded on a scaffold. It is hard to distribute sells evenly over the scaffold and a lot of cells are lost during cell seeding.[1] Coiled cell encapsulate alginate microfiber scaffold enabled not only to overcome these limitation but also to easy control thickness and porosity of scaffold.
We made a fork shape rectangular microchannel with three inlets and one outlet using deep reactive ion etching on silicon substrate and anodic bonding with Pyrex glass. We flowed cell seeded 1% alginate solution whose viscosity is about 15cp and CaCl2 solutions into this channel. Alginate is an anionic polysaccharide capable of reversible gelation in the presence of divalent cations like Ca2+ ions.[2]
Because of high viscosity of alginate solution, viscous encapsulation which is a phenomenon in which a less viscous liquid will tend to encapsulate a more viscous liquid as they flow through a channel occurred. This phenomenon does fabrication of pillar like microfiber in rectangular channel as is possible. The instability due to the stress of two solutions occurring during encapsulation made swirling effect. Because of swirling effect and immisciblity of alginate gel, the outflow of channel formed well ordered coiled shape. We manipulate the porosity of scaffold through controlling diameter of alginate microfiber coil.
We can control the thickness of alginate microfiber and diameter of coil through controlling flow rate of two solutions. The coiled cell encapsulated alginate microfiber is easy method to fabricate scaffold control thickness and porosity without cell seeding process.
[1] E. Lavik and R. Langer, "Tissue engineering: current state and perspectives", Appl. Microbiol. Biotechnol., vol. 65, pp. 1-8, 2004
[2] T. Taguchi, L. Xu, H. Kobayashi, A. Taniguchi, K. Kataoka and J. Tanaka "Encapsulation of chondrocytes in injectable alkali-treated collagen gels prepared using poly(ethylene glycol)-based 4-armed star polymer", Biomaterials, vol. 26, pp. 1247-1252, 2005.
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