A 3D-Printed Composite Hydrogel Engineered with a Coordination-Reprogrammed Nanozyme for Synergistic Chemo-Physical Bone Therapy

Impaired diabetic bone regeneration, driven by excessive reactive oxygen species (ROS) and dysregulated inflammation, is a major clinical challenge. Herein, we engineered a hierarchical 2-dimethylimidazole (Hmim)/polydopamine (PDA) composite and integrated it into a 3D-printed hydrogel scaffold for chemo-physical therapeutic relay. Fabricated via in situ polymerization, the composite reconfigures PDA's coordination environment, optimizes Co²⁺/Co³⁺ modulation, boosts Co loading, and exhibits remarkably enhanced superoxide dismutase (SOD)-like activity. The 3D-printed hydrogel enables localized sustained release of the composite, which scavenges ROS and induces M2 macrophage polarization to correct the pathological microenvironment. Upon NIR irradiation, PDA's photothermal effect further promotes osteogenesis and vascularization, forming a "chemical regulation-physical stimulation" relay.This work develops a composite-based 3D-printed platform and validates the chemo-physical strategy for diabetic bone regeneration.