Polyphosphazene/nano-hydroxyapatite composite microsphere scaffolds for bone tissue engineering

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Orthopedic Engineering

Background:

• Amino acid ester polyphosphazenes offer non-toxic degradation products suitable for orthopedic applications.
• Developing mechanically robust and osteocompatible materials is crucial for load-bearing tissue engineering.
• Biodegradable polymers are essential for creating temporary scaffolds in regenerative medicine.

Purpose of the Study:

• To synthesize and evaluate novel biodegradable polyphosphazenes for bone tissue engineering.
• To investigate the potential of phenylalanine ethyl ester polyphosphazene-hydroxyapatite composites.
• To fabricate and characterize 3-D porous scaffolds for orthopedic applications.

Main Methods:

• Synthesis of three biodegradable polyphosphazenes with leucine, valine, and phenylalanine ethyl ester side groups.
• Fabrication of composite microspheres using phenylalanine ethyl ester polyphosphazene and 100 nm hydroxyapatite (nHAp).
• Sintering of microspheres into 3-D porous scaffolds via dynamic solvent sintering.

Main Results:

• Phenylalanine ethyl ester polyphosphazene exhibited the highest glass transition temperature (41.6°C).
• The 3-D polyphosphazene-nHAp composite scaffolds demonstrated compressive moduli of 46-81 MPa and mean pore diameters of 86-145 µm.
• Scaffolds showed excellent osteoblast cell adhesion, proliferation, and alkaline phosphatase expression.

Conclusions:

• Phenylalanine ethyl ester substituted polyphosphazene is a promising candidate for orthopedic applications.
• The developed 3-D porous polyphosphazene-nHAp composite scaffolds support osteoblast functions.
• These scaffolds represent a viable option for future bone tissue engineering applications.