Antioxidant, Degradable, and 3D-Printable Hydrogels Enabled by a Gelatin-Flavin Conjugate Photoinitiator

The development of novel photoinitiators possessing both photopolymerization activity and biological functionality has become a critical challenge in advancing hydrogel applications in biomanufacturing and precision medicine. Particularly in the fabrication of high-resolution 3D-printed hydrogel constructs, the properties of photoinitiators directly determine polymerization efficiency, printing success, and structural resolution. In this study, a novel flavin derivative, diethyl 2,2′-(7,8-dimethyl-2,4-dioxobenzo [g]pteridine-1,3(2H,4H)-diyl) diacetate (DMLQ-EA), was synthesized and subsequently grafted onto gelatin to produce a gelatin-based flavin macromolecule (Gel-DMLQ). Serving as a dual-functional photosensitive agent, Gel-DMLQ enables rapid photopolymerization of an aqueous solution containing 50% (w/w) 2-hydroxyethyl acrylate (HEA)2-hydroxyethyl acrylate (HEA), resulting in the formation of HEA/Gel-DMLQ hydrogels with radical scavenging activity reaching up to 95% and alkali-triggered degradability. By modulation of the Gel-DMLQ content, the compressive strength of the hydrogels can be significantly enhanced. Additionally, the Gel-DMLQ-based initiator system supports high-resolution 3D printing without additional dyes, demonstrating its potential for advanced biomedical and material applications.