Effect of mixing bioactive nanoceramics with a thermosensitive hydrogel as bone substitute

The composite of methoxy polyethylene glycol (mPEG) and poly(lactic-co- glycolic acid) (PLGA) thermosensitive hydrogel mixed with different mass raio of hydroxyapatite and β-tricalcium phosphate (β-TCP) were used as bone graft substitutes. The physical properties of a series of composite gels, including the critical micelle concentration (CMC), particle sizes, zeta potential, rheological behavior, morphology of composite gels, and sol-gel transition, were characterized in vitro. These composite gels could form a gel at body temperature and could be controlled easily at room temperature. During the in vitro degradation process, composite gels demonstrated a slight decrease in pH value, a slower degradation rate, less toxicity, and a higher cell survival rate. The biocompatibility of the composite gels was validated by hemolysis test. In vivo animal studies demonstrated both radiographic and gross bone union when the ratio of HAP/ β-TCP was 7:3.