Microporous Nano-hydroxyapatite/collagen/phosphatidylserine Scaffolds Embedding Collagen Microparticles for Controlled Drug Delivery in Bone Tissue Engineering

Scaffolds featuring spatiotemporal control of drug release is highly desirable for bone tissue regeneration. The objective of this study was to construct a scaffold with gradient porosity and drug distribution and evaluate the effect of scaffold structure on drug release kinetics and cell bioactivity. Nano-hydroxyapatite/collagen/phosphatidylserine scaffolds embedded with steroidal saponin loaded collagen microparticles were prepared using a porogen leaching protocol. Morphological characterization showed that the scaffolds consisted of dense layer and loose layer, and pores were interconnective. The microparticles were entrapped at the center of the scaffolds follow a gradient distribution. Release kinetics correlated with the structure. The loose layer showed greater drug release amount as compared to the dense layer. Such differences in release kinetics have distinct effects on cell bioactivity. Cell proliferated much more in loose layer than that in the dense layer. Such spatial and temporal control over drug deposition and delivery within the scaffolds could provide opportunities for tissue regeneration associated with optimum drug doses at wound site, and lessen undesirable drug release and side-effects at uninjured site.