Bioinspired thermoreversible bioink orchestrates focal adhesion-dependent osteogenesis

Synergistic integration of bone extracellular matrix (bECM) macromolecules in biomimetic bone tissue engineering (BTE) remains underexplored. This study presents a novel bioink for load-bearing 3D bioprinting (LB-3DBP), comprising gelatin and kappa-carrageenan (κC). Termed 'thermoreversible ionic-covalent entangled (TRICE) bioink', it exhibits exceptional cell viability (>92%), printability, and osteogenic capacity. This advanced multi-material bioprinting approach integrates the TRICE bioink with a calcium phosphate (CaP)-based load-bearing ink. The resulting LB-3DBP scaffolds exhibited a compressive modulus of ~33.2 MPa (comparable with trabecular bone) and up to 200-fold greater strength compared with hydrogel-only bioprints. The (ECM)-inspired TRICE bioink enhanced focal adhesion, proliferation, and MAPK/ERK-mediated osteogenic differentiation. In rabbit femoral condyle models, LB-3DBP scaffolds promoted de novo bone formation and remodeling within 8 weeks. This work bridges mechanical resilience and bioactivity in BTE, offering fully bioresorbable, patient-specific scaffolds that recapitulate the properties of native bone. Thus, our biomimetic, multi-material platform provides a scalable solution for personalized bone regeneration.