In situ preparation of poly(l-lactic acid-co-glycolic acid)/hydroxyapatite composites as artificial bone materials

Abstract

Poly(l-lactic acid-co-glycolic acid)/hydroxyapatite (PLGA/HAp) composites were fabricated by the in situ polymerization of l-lactide and glycolide in porous HAp disks, using lipase MM, derived from Mucor miehei, as a catalyst. Various PLGA/HAp composites were obtained by changing the feed ratio of l-lactide and glycolide. The fourier transform infrared spectroscopy, scanning electron microscopy and porosity measurements showed that the porous HAp was completely filled with PLGA after polymerization at 100 °C for 9 days. Lactyl unit fractions (FL) of obtained PLGA calculated from the 1H nuclear magnetic resonance were consistent with the feed fraction of l-lactide (fL). The PGA/HAp, PLGA20/HAp, PLGA50/HAp, PLGA80/HAp and PLLA/HAp composites showed maximum bending strengths of 91.1 MPa, 78.8 MPa, 73.4 MPa, 54.3 MPa and 67.0 MPa, respectively. These values were 4.7–2.8 times greater than that of the untreated porous HAp disks and were suitable for artificial bone materials. The cell adhesion and proliferation properties of these materials with osteoblast-like MC3T3-E1 cells suggest that these PLGA/HAp composites have suitably bioactive surfaces. The PLGA/HAp composites showed higher alkaline phosphatase activity after cultivation of rat bone marrow stromal cells. Poly(l-lactic acid-co-glycolic acid)/hydroxyapatite composites were prepared by in situ polymerization of l-lactide and glycolide in porous HAp pellets for their application to the artificial bone materials. Effect of l-lactic acid/glycolic acid ratio on the mechanical properties and biocompatibility were investigated.