Rational Design of Multifunctional CuS Nanoparticle‐PEG Composite Soft Hydrogel‐Coated 3D Hard Polycaprolactone Scaffolds for Efficient Bone Regeneration

Abstract 3D‐printed polycaprolactone (PCL) scaffolds have been extensively studied for application in bone tissue engineering. However, PCL‐based scaffolds with enhanced bioactivity and intelligent delivery capability for bone repair remains challenging. Herein, CuS nanoparticle‐PEG soft hydrogel‐coated 3D hard polycaprolactone scaffolds (denoted as CuS‐PEG‐PCL scaffold) are rationally designed for efficient bone regeneration. CuS nanoparticles cross‐linked PEG hydrogel (CuS‐PEG‐hydrogel) endows the PCL‐based scaffold with excellent photothermal properties and stable soft elasticity, while the PCL scaffold provides excellent mechanical performance. Upon exposure to 1064 nm near‐infrared (NIR) light irradiation, dexamethasone sodium phosphate (Dexp), stored in the CuS‐PEG‐PCL scaffold, can be controllably released, which efficiently promotes osteogenic differentiation of bone mesenchymal stem cells (BMSCs). In addition, the combination of mild heating at 42 ± 0.5 °C further promoted osteogenic differentiation of BMSCs. Subsequently, this Dexp‐loaded CuS‐PEG‐PCL scaffold (D‐CuS‐PEG‐PCL scaffold) with NIR light treatment at the tibial defect of rats presented the highest bone regeneration capacity. These findings demonstrate that the Dexp‐loaded CuS‐PEG‐hydrogel can effectively modify the 3D printed PCL scaffold. Therefore, this multifunctional scaffold with a soft‐hard hybrid structure has the potential to become an advanced drug delivery vehicle in the treatment of large bone defects.