Aqueous Two-Phase Emulsion Bioresin for Facile One-Step 3D Microgel-Based Bioprinting

Microgel assembly as void-forming bioinks in 3D bioprinting has evidenced recent success with a highlighted scaffolding performance of these bottom-up biomaterial systems in supporting the viability and function of the laden cells. Here, a ternary-component aqueous emulsion is established as a one-step strategy to integrate the methacrylated gelatin (GelMA) microgel fabrication and assembly through vat photopolymerization in situ using digital light processing (DLP)-based bioprinting. The as-proposed aqueous emulsion is featured with the partitioning of a secondary photo-crosslinkable polysaccharide, methacrylated galactoglucomannan (GGMMA) derived from plant source in both the dispersed phase of GelMA droplets and the continuous phase of dextran (Dex). As an emulgator, GGMMA renders enhanced stability of the aqueous emulsion bioresins. Strategically, the photo-crosslinkable GGMMA adheres the GelMA microgels that are conveniently converted from emulsion droplets to form hydrogel construct in layer-by-layer curing to accommodate the laden cells directly mixed in the aqueous emulsion. The spatially interconnected void space left by the removal of Dex benefits the cell growth under the guidance of the microgel surface and supports cell colonization within the macroscopic porous hydrogel. This work amends a low-concentration and cost-effective bioresin that is highly applicable for facilely fabricating microgel assembly as a porous hydrogel construct in DLP-based bioprinting.