Synergistic complexation of phenol functionalized polymer induced in situ microfiber formation for 3D printing of marine-based hydrogels

The design of 3D printable bio-based hydrogels with enhanced mechanical properties and minimal chemical modification can open new opportunities in the field of biomedical applications. A facile and safe approach is proposed to prepare mechanically reinforced chitosan-based hydrogels via a phenolated polyelectrolyte complex (PHEC) and enzyme-mediated crosslinking. PHEC was formed between phenolated chitosan and alginate, leading to the formation of in situ phenol-functionalized microfibers that exhibited excellent 3D printability. The synergistic complexation enhanced the loss modulus (60 times), toughness, flexibility, and moldability of hydrogel as well as dynamic viscosity (20 times) of the hydrogel precursor compared to individual phenolated chitosan and alginate hydrogels. This complexation endowed the material with excellent printability without sacrificing the hydrogel's elasticity. This study proposes a strategy to design tough and 3D printable marine-based hydrogels based on the synergistic complexation of a phenolated polyelectrolyte complex and enzyme-mediated crosslinking.