Comparison of PLGA reinforcement method for carbonate apatite foam

Carbonate apatite (CO₃Ap) foam with interconnecting porous structure is a potential candidate as bone substitute material owing to its similarity to the cancellous bone with respect to composition, morphology and osteoclastic degradation. However, it is brittle and difficult to handle. This is thought to be caused by no organic material in the CO₃Ap foam. The aim of this study is to reinforce the CO₃Ap foam with poly(DL-lactide-co-glycolide) (PLGA). Immersion and vacuum infiltration methods were compared as reinforcing methods. Compressive strength of unreinforced CO₃Ap foam, (12.0 ± 4.9 kPa) increased after PLGA reinforcement by immersion (187.6 ± 57.6 kPa) or by vacuum infiltration (407 ± 111.4 kPa). Scanning electron microscopy (SEM) showed the preservation of full interconnecting porous structure of CO₃Ap foam after PLGA reinforcement using immersion or vacuum infiltration. Interface between the PLGA and CO₃Ap foam, however revealed that no gap was found between the PLGA and CO₃Ap foam interface when vacuum was used to reinforce the PLGA whereas a gap was found when simple immersion was used. Strong interface between PLGA and CO₃Ap foam is therefore thought to be the key for higher compressive strength. In conclusion, vacuum infiltration is a more efficient method to reinforce the CO₃Ap foam with PLGA for improving the mechanical strength without sacrificing the cancellous bone-type morphology.