Photocurable cellulose nanofibers and their copolymers with polyacrylamide as microgels to support 3D cell cultivation

Cellulose nanofibers (CNFs) are renewable bionanomaterials with great utilization potential in future biomedicals. However, conventional CNF hydrogels are limited by low structural flexibility and insufficiently tunable mechanical properties, restricting their use in 3D cell culture systems. To address these limitations, we developed granular hydrogel platforms using photocurable and ionically crosslinkable methacrylated CNFs (CNFMAs) and their copolymers with polyacrylamide via a dual cross-linking mechanism. By employing this bottom-up approach, mechanically fragmented microgels were reassembled into granular hydrogels via calcium ion crosslinking. This assembly of methacrylated CNF-based microgels successfully supported long-term 3D cell culture and demonstrated the capability to provide biomechanical cues that facilitate different cellular responses. The granular hydrogel of CNFMA alone promoted clustering and migration of human pancreatic cancer cells (PANC-1), while the copolymerization of CNFMA with polyacrylamide introduced stiffness variations into the hybrid granular hydrogel system that enhanced the spreading of preosteoblasts (MC3T3-E1) and facilitated spheroid formation in the culture of PANC-1. These findings underscore the versatility of photocurable nanocellulose in constructing biomaterial platforms. Overall, this study establishes a foundation for advancing in vitro models for tissue engineering and cancer research using CNFMA-derived microgel systems.