Recent Advances in Biopolymer Modifications for the Generation of 3D Printable Hydrogels

The growing demand for sustainable materials has driven interest in biopolymer-based 3D printing, yet their limited extrudability and shape fidelity restrict direct application. This review summarizes recent advances in the molecular design of protein- and polysaccharide-based hydrogels through chemical modification, introducing cross-linkable groups that enhance shear-thinning for extrusion, self-healing for shape fidelity, and controlled gelation for structural stability, thereby overcoming these limitations. Emerging granular hydrogels are also highlighted as next-generation 3D-printable bioinks. Significantly, this review bridges the knowledge gap by elucidating the molecular rationale linking chemical modifications to key ink properties and their functional performance, particularly in customizing food structures with tailored textures and nutrient delivery profiles, and in designing tissue-engineering scaffolds that balance structural fidelity with biological functionality to support cell-laden printing and tissue regeneration. Overall, this review first establishes a molecular framework linking biopolymer modification to 3D printing outcomes, guiding next-generation biofabrication technologies across food and biomedical fields.