Single-Print Scaffold Mimics Bone-Cartilage Interface

Scientists have long aimed to build a scaffold that smoothly transitions from bone to cartilage. A new approach uses a single‑step melt electrowriting technique to embed a mineral gradient directly into a polymer scaffold. The polymer is poly(ε‑caprolactone) and the mineral added is nanohydroxyapatite.

This compositional gradient drives a corresponding reduction in fiber diameter, creating a structural gradient that mirrors the natural interface between subchondral bone and cartilage. The scaffold therefore exhibits graded composition, structure, and mechanical properties.

To enhance cartilage formation, a porous hydrogel coating containing TGF‑β1 is applied to the scaffold. The coating provides localized chondrogenic signals without blocking the interconnected pores, allowing cells to migrate and receive cues simultaneously.

In vitro experiments with human bone marrow mesenchymal stem cells show coordinated osteogenic and chondrogenic differentiation on the scaffold. In animal models, the scaffold promotes integrated repair of the osteochondral defect. The method establishes a versatile platform for single‑step gradient encoding in tissue engineering.