by Pohang University of Science and Technology

Injectable adhesive hydrogel for bone regeneration that simultaneously induces cross-linking and mineralization with visible light. Credit: POSTECH

A research team has developed an innovative injectable adhesive hydrogel for bone regeneration. This hydrogel utilizes harmless visible light to simultaneously achieve cross-linking and mineralization without the need for bone grafts. The research was recently published in the journal Biomaterials.

Bone defects, which arise from various causes such as trauma, infection, and congenital abnormalities, are becoming increasingly common in aging societies. Conventional treatments often involve bone grafts combined with serum or bioadhesives to fill the defect.

However, existing injectable hydrogels face challenges such as difficulty in maintaining their shape within the body and limited adhesive strength. Moreover, traditional methods using bone grafts with adhesive materials often fail to achieve simultaneous “bone regeneration” and “adhesion.”

The POSTECH team has introduced a novel system that addresses these limitations. This new hydrogel system employs visible light—safe for the human body—to facilitate cross-linking, where the main components of the hydrogel bond and harden, and to simultaneously boost mineralization where bone-building minerals like calcium and phosphate form within the hydrogel.

While earlier studies have explored the use of light in similar applications, they encountered issues such as requiring separate preparation and mixing of bone grafts and adhesive materials, as well as weak bonding of the main components, which often degraded over time.

The newly developed hydrogel precursor comprises alginate (natural polysaccharide derived from brown algae), RGD peptide-containing mussel adhesive protein, calcium ions, phosphonodiols, and a photoinitiator. The coacervate-based formulation, which is immiscible in water, ensures that the hydrogel retains its shape and position after injection into the body.

Upon visible light irradiation, cross-linking occurs, and amorphous calcium phosphate, which functions as a bone graft material, is simultaneously formed. This eliminates the need for separate bone grafts or adhesives, enabling the hydrogel to provide both bone regeneration and adhesion.

In experiments using animal models with femoral bone defects, the hydrogel was successfully injected, adhered accurately, and effectively delivered components essential for bone regeneration.

Professor Hyung Joon Cha from POSTECH commented, “The injectable hydrogel system for bone regeneration developed by our research team represents an innovative alternative to conventional complex treatments for bone diseases and will greatly advance bone tissue regeneration technology.”

The research team included Professor Cha from POSTECH’s Department of Chemical Engineering and Graduate School of Convergence Science and Technology with a specialization in Medical Science, along with Dr. Jinyoung Yun and Integrated Program student Hyun Taek Woo from the Department of Chemical Engineering.

More information: Jinyoung Yun et al, Visible light-induced simultaneous bioactive amorphous calcium phosphate mineralization and in situ crosslinking of coacervate-based injectable underwater adhesive hydrogels for enhanced bone regeneration, Biomaterials (2024). DOI: 10.1016/j.biomaterials.2024.122948

Journal information:Biomaterials

Provided by Pohang University of Science and Technology

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