Batch Fabrication of Microscale Gear-Like Tissue by Alginate-Poly-L-lysine (PLL) Microcapsules System

Abstract

Constructing 3D cell module with certain shape and high cell density is a very important issue for artificial tissue engineering. In this letter, we present a novel method of fabricating compact microtissue with gear-like shape by electrodepositing of $\text{Ca}^{2+} $ induced cross-linked alginate hydrogel. The fabrication procedure is demonstrated and the fabricated gear-like tissues are characterized. Briefly, an array of gear-shaped microelectrodes are first fabricated by coating a patterned photoresist layer onto fluorine-doped tin oxide (FTO) glass slide based on photolithography technique. Then, Ca-alginate gel structures embedded with RLC-18 (rat liver) cells are electrodeposited onto the microelectrodes. These 2D cell-laden gel structures are then manually detached from the microelectrodes and treated with special reagent to be transformed into 3D alginate-Poly-L-lysine (PLL) microcapsules while maintaining the gear shape. Finally, the RLC-18 cells within the microcapsules are further promoted into compact microtissues by cultivation. The size of the fabricated gear-like tissue is about $975{\pm }{25}\;\upmu \text{m}$ in outer diameter and $320{\pm }{10}\;\upmu\text{m}$ in inner diameter based on the design of microelectrodes. 3-D images of the fabricated microtissues are obtained by a confocal microscope. The experimental results indicate the proposed method can successfully fabricate movable microtissues with predefined gear shape while maintaining the viability ( $\sim 94\%$ ). We believe the fabricated movable gear-like microtissues can be further assembled and applied to tissue engineering.