Effect of n-HA with different surface-modified on the properties of n-HA/PLGA composite

Three different surface modification methods for nano-hydroxyapatite (n-HA) of stearic acid, grafted with l-lactide, combining stearic acid and surface-grafting l-lactic were adopted, respectively. The surface modification reaction and the effect of different methods were evaluated by Fourier transformation infrared (FTIR), X-ray photoelectron spectra (XPS), thermal gravimetric analysis (TGA), transmission electron microscopy (TEM). The results showed that n-HA surfaces were all successful modified, and the modification method of combining stearic acid and surface-grafting l-lactic had the greatest grafting amount and the best dispersion among the three modification methods. Then, the n-HA with three different surface modification and unmodified n-HA were introduced into PLGA, respectively, and a serials of n-HA/PLGA composites with 3% n-HA amount in weight were prepared by solution mixing, and the properties of n-HA/PLGA composites were also investigated by electromechanical universal tester and scanning electron microscope(SEM), comparing with PLGA. The results showed that the n-HA/PLGA composite with the n-HA surface modified by combining stearic acid and surface-grafting l-lactic had the highest bending strength and the best dispersion and interfacial adhesion among the three different modification methods, suggesting the surface modification of combining stearic acid and surface-grafting l-lactic was the most ideal method in this study, which has a great deal of enhancement of bending strength than PLGA, and it would be potential to be used in the field of bone fracture internal fixation in future.