Poly(l-lactide)/cyclodextrin/citrate networks modified hydroxyapatite and its role as filler in the promotion to the properties of poly(l-lactide) biomaterials

In this work, hydroxyapatite (HA) was modified by chelation of citric acid and Ca on the surface of HA, followed by the cross-linking between the hydroxyl groups of β -CD and citrate, and then the further in situ ring-opening polymerization (ROP) of l -lactide over the hydroxyl groups. The as-synthesized filler were characterized by FT-IR, XRD , TGA , and SEM. The results showed that HA was successfully modified with β -CD/citrate/PLA networks. The grafting amount of PLA-CD-HA-72 ( β -CD/citrate/PLA) is up to 15.0 wt%, while the amount of PLA is 11.7 wt%. The modification of HA greatly improves the bioactivity. Comparing the synthesized samples, PLA-CD-HA-72 shows a better cell adhesion and higher viability to the mesenchymal stem cells (MSCs) of Wistar rat. Also the osteoinductivity of the PLA-CD-HA-72 is much higher than the others. Various composites are prepared by PLLA filled with HA, CD-HA and PLA-CD-HA-72, respectively. Among these composites, tensile strength of the PLA-CD-HA-72/PLLA with 2.5 wt% of filler reached 41.7 ± 2.2 MPa, which is much higher than that of the pure PLLA (31.7 ± 1.3MPa). The addition of the PLA-CD-HA-72 significantly improves the bioactivity and mechanical properties of the composite simultaneously. This kind of composite with good biocompatibility and mechanical properties is a good candidate for promising bioresorbable material.