Controlled assembly of poly(d,l-lactide-co-glycolide)/hydroxyapatite core–shell nanospheres under ultrasonic irradiation

An ultrasound field was applied to obtain PLGA/HAp biocomposite nanospheres. Formulation of PLGA/HAp composite revealed significant dependence of the morphology of the obtained composite on synthesis parameters, like the intensity of applied ultrasonic field, polymeric and ceramic parts’ wt.% ratio in the composite, temperature of the medium, type of surfactant, and the sequence of steps in the formation of PLGA/HAp. Optimal parameters for the formation of PLGA/HAp included a lower content of the ceramic phase (PLGA/HAp = 90:10), higher power of ultrasonic field (P = 142.4 W), lower temperature of the medium during ultrasonic treatment (T = 8 °C), dilute solution of PVP as surfactant and dispersion of hydroxyapatite in polymer solution in order to achieve required homogeneity before the formulation of the composite. The morphology of PLGA/HAp particles synthesized under these conditions was highly regular: sphere-like, with particles of very small dimensions (150–320 nm), highly uniform particle size distribution and characteristic planar spatial self-organization. These characteristics indicate significant improvements in PLGA/HAp composite resulting from ultrasonic method.