Preparation of photothermal-sensitive PDGF@ZIF-8-PDA@COL/PLGA-TCP composite scaffolds for bone defect repair

The repair of bone defects has long been a challenging and significant health question. Here, collagen hydrogel incorporating platelet-derived growth factor (PDGF)-loaded photopolymerizable ZIF-8-PDA nanoparticles ([email protected]@COL hydrogel) was prepared and perfused into 3D printed poly (lactide-co-glycolide)-tricalcium phosphate (PLGA-TCP) scaffolds. The resulting [email protected]@COL/PLGA-TCP composite scaffolds were applied as a bone substitute for cranial bone defect repair. The photopolymerizable ZIF-8-PDA nanoparticles had a mean size of 226.2 ± 5.3 nm with photothermal conversion capacity. [email protected]@COL/PLGA-TCP composite scaffolds showed a slower release of PDGF compared to PDGF release from collagen hydrogels. The composite scaffolds exhibited excellent antibacterial properties and good in vitro osteoconductive capacity. The osteoconductive activities of [email protected]@COL/PLGA-TCP composite scaffolds were also investigated in a rat cranial bone defect model in vivo by micro-CT imaging, hematoxylin and eosin staining, Masson's trichrome staining, and immunohistochemical staining of osteogenesis-related markers. The [email protected]@COL/PLGA-TCP composite scaffolds accelerated cranial bone formation and gradually degraded over time. All these results provided strong evidence that [email protected]@COL/PLGA-TCP composite scaffolds might be a promising system for bone defect repair.