Preliminary synthesis and characterization of poly(lactic acid)/chitosan/n-hydroxyapatite composite scaffolds for bone tissue engineering

Chitosan (CS) is a biodegradable polymer that has been used in fabricating bone tissue engineering (BTE) scaffolds because of its structural similarity to glycosaminoglycans, a vital component of the extracellular matrix (ECM) of bone. However, due to its low mechanical strength, further applications of chitosan in bone scaffolds were limited. Poly(lactic acid) (PLA) is a non-toxic, biodegradable synthetic polymer with excellent mechanical strength properties. Nano-sized hydroxyapatite (n-HAp) is currently the material of choice for various biomedical applications, such as bone substitutes, drug delivery agents, and bone tissue engineering, thanks to its excellent osteoconductivity, bioactivity, and high compatibility with surrounding tissues. In our previous work, 3D CS/n-HAp scaffolds were successfully fabricated and tentatively applied for bone tissue engineering applications, but those scaffolds revealed medium mechanical strength in value. In this work, PLA was blended into the CS/n-HAp system to synthesize 3D CS-PLA/n-HAp scaffolds for further increasing the mechanical strength of the CS-nHAp. The mixture of three phases, CS, PLA, and n-HAp, was freeze-dried at low temperatures to produce 3D CS-PLA/n-HAp scaffolds. The synthesized scaffolds are characterized by XRD, SEM, and liquid displacement. Their biocompatibility and bioactivity was evaluated through in vitro test in the biological environment. Results demonstrated that the synthesized scaffolds have highly porous structures with an average porosity of 75%. The PLA-CS/n-HAp scaffolds exhibited relatively high biomineralization, releasing a bone-like apatite layer on the surfaces after 5 days of incubating in simulated body fluids. The work suggested that the PLA-CS/ HAp scaffold is a potential biomaterial for BTE applications.