Preparation and Properties of Biodegradable Composites Derived from Poly(lactide-co-glycolide), Poly(L-lactide), and Nanohydroxyapatite

Poly(L-lactide-co-glycolide) (PLGA), poly(L-lactide) (PLLA), and nanohydroxyapatite (HA) were used to prepare a biodegradable bone fixation composite PLGA/PLLA/HA via blending and melt-molding methods. The ratio of PLGA, PLLA, and HA was set to 75.0, 20.0, and 5.0 wt%, respectively, and the neat PLGA and PLGA/PLLA blend were used as controls. Thermal properties were analyzed using thermogravimetric analysis. Mechanical properties, including flexural strength and flexural modulus, were tested before and after degradation. Biodegradability of the resulting PLGA/PLLA/HA composite at the 10th-90th days was analyzed by testing its mass and pH value changes during different degradation periods, as well as by observing its fracture surface morphology changes by scanning electron microscopy. The in vitro cytotoxicity test of the PLGA/PLLA/HA composite was assayed by evaluating the relative growth rate of HEK-293 and Hela cells on sample bars. The results indicate that the resulting PLGA/PLLA/HA composite retained better mechanical properties and degradation behavior than the neat PLGA and PLGA/PLLA blend. Meanwhile, the cytotoxicity test showed that the PLGA/PLLA/HA composite had no obvious cytotoxicity effect.