A continuously 3D-printed biomimetic periosteum-bone scaffold based on polylactic acid/quaternized...

Clinically, the repair of critical bone defects remains a significant challenge, and conventional single-layer scaffolds demonstrate constrained performance owing to their inability to mimic the hierarchical structure and complex functions inherent to natural bone. This study introduced a continuously 3D-printed biomimetic periosteum-bone integrated scaffold, which was designed to mimic the physiological structure of bone. The scaffold consists of an upper quaternary chitosan/carboxymethyl cellulose (CMC) loaded with MCol and magnesium ion (CMC/QCS@MCol+Mg²⁺, CQ@MM) and a lower polylactic acid/polydopamine scaffold (PLA/PDA, PP). In the whole PP-QC@MM bilayer implant, the lower PP scaffold provides excellent mechanical properties for the entire implant. While the upper CQ@MM bioinspired periosteum scaffold enables sustained release of MCol and Mg²⁺ via CMC/QCS loading. Critically, phenolic groups on the PP surface form hydrogen bonds with amino groups in CQ@MM, enabling stable interfacial bonding to integrate bioinspired periosteal-bone scaffold. Additionally, the upper CQ@MM scaffold further accelerates bone repair by promoting neural repair, as well as enhancing vascularized bone regeneration and antibacterial property. The PP-QC@MM bioinspired periosteal-bone integrated scaffold significantly promoted bone regeneration in a rat cranial critical defect model, establishing a novel strategy and theoretical basis for the repair of critical-sized bone defects.