Preparation and in vitro bioactivity of poly(D,L-lactide) composite containing hydroxyapatite nanocrystals

The nano-sized hydroxyapatite (n-HA) was incorporated into poly(D,L-Lactide) (PDLLA) to form a bioactive and biodegradable composite for application in hard tissue replacement and regeneration. Thin film of PDLLA composite containing 20 mass% of n-HA fillers was successfully developed through integration of solvent co-blending and hot pressing techniques. firstly, n-HA and PDLLA were chemically synthesized, respectively, then mixed together and homogeneously dispersed in N,N-dimethyl formamide(DMF) solvent, finally, the dried blended hybrid containing PDLLA matrix and n-HA fillers was put into the mould and compacted by hot-pressing machine under 8 MPa pressure at 110 degrees C for 15 min. In vitro studies were conducted using the simulated body fluid(SBF). Composite specimens were soaked in SBF from I day to 21 days prior to surface analysis. Results obtained from scanning electron microscopy(SEM) examination, Energy dispersive X-ray detector(EDX) analysis and Xray diffraction (XRD) analysis showed that a layer of non-stoichiometric apatite formed within 7 days on HA/PDLLA composite surface after its immersion in SBF, demonstrating moderate in vitro bioactivity of n-HA/PDLLA composite, though a moderate rate of apatite formation in SBF was found on initial stage of immersion periods for n-HA/PDLLA composite, compared to the other biomaterial composite. This type of composite film exhibited certain desirable bioactive characteristics, and they are promising bone candidates to develop novel bioactive composites for biomedical application. (C) 2008 Elsevier B.V. All rights reserved.