Electrosynthesis of Janus Alginate Hydrogel Microcapsules with Programmable Shapes for Cell Encapsulation

Hydrogel microcapsules provide well-defined and biocompatible platforms for 3D cell culture, which is greatly desired for replacing, or enhancing the function of damaged human tissue and in vitro tissue regeneration. Since Alginate-poly-L-lysine alginate microcapsules can provide a liquified environment for biomaterials, traditional fabrication methods such as microfluidic gelation can tune the size and biochemical properties of hydrogel microcapsule, but still, undergo tremendous challenges while tuning the morphology of the hydrogel microcapsules. In this work, we proposed a novel approach to fabricate Janus Alginate-Poly-L-lysine Alginate microcapsule with controllable shape and size based on a two-step hydrogel electrodeposition method. The microelectrode device (fluorine-doped tin oxide (FTO) glass) was etched into two insulating parts by laser processing. After the first step, the electrodeposition solution was removed by adding HEPES solution. During secondary electrodeposition, a higher voltage was employed, since the entrapped hydrogel and unremoved HEPES solution remains upon the surface of the fluorine-doped tin oxide (FTO) glass. After the two-step deposition, the 2D hydrogel Janus structures were detached from the FTO glass. Then they were immersed in Poly-L-lysine solution. Then the 3D Alginate-poly-L-lysine alginate (APA) microcapsules were successfully fabricated and incubated for further observation. We have demonstrated a successful encapsulation of HepG-2 cells in the half of the APA hydrogel microcapsule and the cells are cultured for several days and Janus APA microcapsules are embedded with fluorescence-labelled and non-labelled HepG2 cells to monitor the cell morphology, distribution, as well as their proliferation.