Improved cell viability for large-scale biofabrication with photo-crosslinkable hydrogel systems through dual-photoinitiator approach
Biofabrication with various hydrogel systems allows production of tissue or organ construct in vitro to address various challenges in healthcare and medicine. In particular, photocrosslinkable hydrogels have great advantages such as excellent spatial and temporal selectivity and low processing cost and energy requirement. However, inefficient polymerization kinetics of commercialized photoinitiators upon exposure to UV-A or visible light increase processing time, often compromising cell viability. In this study, we developed a hydrogel crosslinking system which exhibited efficient crosslinking properties and desired mechanical properties with high cell viability, through a dual-photoiniator approach. Through co-existence of Irgacure 2959 and VA-086, the overall crosslinking process was completed with the minimal UV dosage during a significantly reduced crosslinking time, producing mechanically robust hydrogel constructs, while most encapsulated cells within the hydrogel construct remained viable. Moreover, we fabricated a large PEGDA hydrogel construct with a single microchannel as a proof of concept for hydrogel with vasculature to demonstrate the versatility of the system. Our dual-photoinitiator approach allowed the production of this photocrosslinkable hydrogel system with microchannels, significantly improving cell viability and processing efficiency, yet maintaining good mechanical stability. Taken together, we envision concurrent usage of photoinitiators, Irgacure 2959 and VA-086, opening potential avenues for utilization of various photocrosslinkable hydrogel systems to perfusable large artificial tissue for in vivo and ex vivo applications with improved processing efficiency and cell viability.