3D printing of metal-organic framework nanosheets-structured scaffolds with tumor therapy and bone construction

After surgical resection for a bone tumor, the uncleared bone tumor cells can multiply and causerecurrence of the bone tumor. It is worthwhile to design a scaffold that kills the remaining bone tumorcells and repairs bone defects that were given rise to by surgical resection. Additionally, it is extremelyimportant to consider the function of angiogenesis in the process of bone regeneration because thenewly formed blood vessels can offer the nutrients for bone regeneration. In this work, a novel metalorganicframework Cu-TCPP nanosheets interface-structured β-tricalcium phosphate (TCP)(Cu-TCPP-TCP) scaffold was successfully prepared through integrating a 3D-printing technique withan in-situ growth method in a solvothermal system. Owing to the excellent photothermal effect ofCu-TCPP nanosheets, Cu-TCPP-TCP scaffolds that were illuminated by near-infrared (NIR) lightdemonstrated photothermal performance, which was well regulated through varying the contents ofCu-TCPP nanosheets, and the ambient humidity and power density of NIR light. When cultured withosteosarcoma cells, Cu-TCPP-TCP scaffolds killed a significant quantity of osteosarcoma cellsthrough released heat energy after exposure to NIR light with power density 1.0Wcm−2 and duration10 min. Similarly, Cu-TCPP-TCP scaffolds ablated subcutaneous bone tumor tissues on the backs ofnaked mice and suppressed their growth because of the heat energy transformed from NIR light. Invitrostudies found that Cu-TCPP-TCP scaffolds ably supported the attachments of both human bonemarrow stromal cells (HBMSCs) and human umbilical vein endothelial cells (HUVECs), andsignificantly stimulated expressions of osteogenesis differentiation-related genes in HBMSCs andangiogenesis differentiation-related genes in HUVECs. After implanting Cu-TCPP-TCP scaffoldsinto the bone defects of rabbits, they effectively promoted bone regeneration. Thus, the integration ofthe bone-forming bioactivity of TCP scaffolds with the photothermal properties of Cu-TCPPnanosheets and angiogenesis activity of Cu ions makes Cu-TCPP-TCP scaffolds multifunctional,representing a new horizon to develop biomaterials for simultaneously curing bone tumors andrepairing bone defects