Nano-hydroxyapatite reinforced polyhydroxybutyrate composites: A comprehensive study on the structural and in vitro biological properties

Nanocomposites based on polyhydroxybutyrate (PHB) and hydroxyapatite (HAp) have recently been proposed for application in bone repair and regeneration, but very limited studies have investigated the effect of HAp on the rheological and thermal behavior of PHB. More important, the efficiency of a biomaterial depends greatly on its ability to interact with cells, but little is known about this interaction for this kind of nanocomposite. Hence, this paper dealt with some of the characteristics of solution-casted PHB/HAp nanocomposite films, and tried to explore the effect of HAp nanoparticles on cellular responses. The results showed that both rheological and thermal properties can be tailored by incorporating appropriate amounts of nanoparticles. In vitro studies showed a significant increase in proliferation and differentiation of MC3T3-E1 on nanocomposites compared to the neat polymer. Surface examination indicated that topography and chemistry of surface are important factors influencing cellular processes; while no cell differentiation was found on the neat polymer, nanocomposite with 15 wt.% filler content exhibited a pronounced differentiation resulting from high surface roughness and large amount of exposed HAp. These results suggest that HAp particles play a much more important role in determining the biological performance of PHB than has previously been supposed. Highlights: • Preosteoblastic MC3T3-E1 cells exhibit an elongated shape in the presence of HAp. • The as-prepared nanoparticles acted as nucleating agent during PHB crystallization. • HAp efficiently induces cell proliferation and differentiation on PHB surface. • HAp nanoparticles significantly affect both the surface chemistry and topography. • A method was provided to simultaneously measure biomineralization and bioactivity