Breakthrough in Bone Regeneration: 3D-Printed Scaffold Hardens Inside the Body

A new study in Advanced Functional Materials reports a major step forward in bone tissue engineering: a 3D-printed mechanically tunable bone scaffold that remains flexible during surgery and subsequently hardens once implanted in the body. 

The scaffold is made of calcium phosphate and polycaprolactone (PCL), a biocompatible polymer widely used in medical applications. What makes it unique is its mechanical tunability, the ability to remain soft during surgery and then harden in vivo, adapting perfectly to the patient’s anatomy and the mechanical demands of the defect site.

The hardening process is activated by physiological conditions, allowing the scaffold to become progressively stiffer after implantation. The ductile-to-rigid transition provides a unique advantage for implantation in anatomically complex sites requiring both adaptability and stability, providing immediate structural support while creating a bioactive environment that promotes bone regeneration.

Animal studies have shown encouraging results: structural integration, biocompatibility, and bone growth. Compared to traditional implants, which often require prefabrication and multiple surgeries, this approach offers a single-step, patient-specific solution. 

The potential applications are broad, ranging from cranofacial reconstruction to long bone repair. While further clinical research is needed,this innovation could reshape orthopedic surgery by combining customization, simplicity, and biological effectiveness in a single platform.

Read the full  paper: M. Mateu-Sanz, P. Varela, L. del-Mazo-Barbara, I. Lodoso-Torrecilla, E. Jiménez-Piqué, J. Franch, M. Alaminos, M.P. Ginebra. Mechanically Tunable Bone Scaffolds: In Vivo Hardening of 3D-Printed Calcium Phosphate/Polycaprolactone Inks. Adv. Funct. Mater. 2025, e09357. https://doi.org/10.1002/adfm.202509357. OPEN ACCESS.