Degradation of poly (DL-lactic acid-co-glycolic acid) containing calcium carbonate and hydroxyapatite fillers--effect of size and shape of the fillers--.

The effects of size and shape of calcium carbonate (CC) and hydroxyapatite (HA) fillers on the degradation of poly(DL-lactic acid-co-glycolic acid) (PLGA) were examined in the PLGA composite films containing 50 mass% of the fillers. The composite and unfilled films were prepared by our method reported previously. The films were immersed in phosphate-buffered saline (pH 7.4) at 37 degrees C for up to 12 weeks. The fate of the films was monitored by weighing and size exclusion chromatography. Blending HA and CC fillers to PLGA retarded the degradation of the PLGA matrix by obstructing the autocatalytic effect caused by carboxylic acid end groups. CC was a little more effective in retarding the degradation than HA. The size of the fillers showed a significant effect on the degradation. The effect of size was more marked in HA than in CC filler. The shape of CC filler had little effect on the degradation in the two shapes studied.