Innovation and Partnerships Office

Injectable Hydrogel-Based Biodegradable Bone Replacement Materials IB-2398


  • Bone implants
  • Dental implants
  • Injectable bone cements
  • Drug delivery
  • Scaffolds for bone tissue engineering


  • Promotes natural bone growth as it biodegrades
  • Improves mechanical performance and tissue-implant interactions of orthopedic materials
  • Simplifies application with injectable slurry that solidifies at target site
  • Exhibits unusually high resilience to compression and fracture
  • Incorporates up to 70% mineral content into hydrogels for a wide range of applications
  • Enables drug or chemical delivery to aid bone growth or treat diseases


The most common nonmetallic material for treating bone defects is PMMA-based Plexiglas, originally designed for nonbiological applications, which is brittle and prone to mechanical fatigue failures.

To improve the mechanical performance and tissue interactions of implant materials, Tony Tomsia, Eduardo Saiz, and colleagues at Berkeley Lab have developed a new generation of organic/inorganic composite materials that mimic the structure and composition of bone. These pHEMA-hydroxyapatite (HA) composite materials are both biocompatible and biodegradable, promoting bone growth as they degrade.

The Berkeley Lab material is one of these new composites. Tailored biodegradation and mechanical properties of this bone replacement material, which uses crosslinked pHEMA in the presence of different types of HA powder in an aqueous solvent, promotes new bone growth as it gradually decomposes. The rate of decomposition, and the mechanical response, can be manipulated for specific applications. The composite can also act as a drug or chemical delivery system to promote bone growth or treat diseases as it degrades.

The Berkeley Lab material is flexible and can withstand an unusually high degree of compression and distortion while retaining its shape. It can easily be cut into desired shapes and sizes. The elasticity of the composites creates a good fit (by compression) into an area of bone defect. Alternatively, because all of the components are water soluble, the material can be Hed into the target site as a slurry that cures within minutes. Due to its elastomeric properties, the Berkeley Lab composite may better accommodate the inherent micro-movement of bone, particularly at the bone-graft interface, thus reducing potential graft failure.

The unique biocompatible and biodegradable properties of Berkeley Lab’s new composite make it an inexpensive and attractive clinical candidate for orthopedic applications with moderate mechanical loads.


  • Issued U. S. Patent 8,344,042 available at Available for licensing or collaborative research.

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Tomsia, A.P., Saiz, E., Song, J., Bertozzi, C.R., “Biomimetic bonelike composites and novel bioactive glass coatings“. Advanced Engineering Materials, 2005. 7(11): p. 999-1004.

Zhao, D., Liu, G., Saiz, E., Tomsia, A.P., Hydrogel-based bone replacement material,” Polymeric Materials: Science & Engineering, 2007. 97: p. 753.