Constructing highly bioactive and tough polyurethane bone adhesives by covalently integrating nanohydroxyapatite

Area of Science:

• Biomaterials Science
• Orthopedic Surgery
• Polymer Chemistry

Background:

• Developing bone adhesives with both mechanical robustness and osteogenic properties is a significant challenge in orthopedic research.
• Existing bone cements often lack sufficient biocompatibility or bioactive integration with surrounding bone tissue.

Purpose of the Study:

• To create a novel polyurethane-based bone adhesive by incorporating aminated nanohydroxyapatite (nHA-NH2) into a biodegradable poly(ε-caprolactone) urethane (PCLU) network.
• To evaluate the mechanical properties, biocompatibility, osteogenic potential, and in vivo bone regeneration capabilities of the developed adhesive.

Main Methods:

• Covalent incorporation of aminated nanohydroxyapatite (nHA-NH2) into a biodegradable poly(ε-caprolactone) urethane (PCLU) network to form PCLU-g-nHA.
• Assessment of compressive modulus and lap-shear adhesive strength.
• In vitro studies using bone marrow mesenchymal stem cells (BMSCs) to evaluate biocompatibility and osteogenic differentiation via transcriptomics.
• In vivo evaluation in rabbit femoral condyle defect and tibial fracture models, comparing with commercial PMMA bone cement.

Main Results:

• PCLU-g-nHA demonstrated significantly enhanced compressive modulus (4.91 MPa) and adhesive strength (3.41 MPa).
• The adhesive exhibited rapid curing under mild conditions with minimal heat release and improved biocompatibility.
• In vitro studies showed stimulation of BMSC osteogenic differentiation, with transcriptomics revealing upregulation of ECM remodeling and collagen synthesis pathways.
• In vivo results indicated superior bone regeneration and osseointegration compared to PMMA bone cement in rabbit models.

Conclusions:

• The developed PCLU-g-nHA bone adhesive successfully integrates mechanical strength with osteogenic bioactivity.
• This novel biomaterial demonstrates significant potential for enhancing bone regeneration and osseointegration, offering a promising alternative to current bone cements.
• The study presents a scalable strategy for creating advanced bone adhesives with clinical translational potential.