Preparation and in vitro/in vivo evaluations of dimpled poly(L-lactic acid) fibers mixed/coated with hydroxyapatite nanocrystals

A novel hydroxyapatite (HAp)/poly(l-lactic acid) (PLLA) nanocomposite nonwoven fabric, which was coated and mixed with calcined HAp nanocrystals, and has submicron-sized dimples on its surface, was fabricated. First, HAp-mixed PLLA fabric was prepared by electrospinning a HAp nanocrystal dispersion in dichloromethane (DCM)-dissolved PLLA. It was found that most of the HAp nanocrystals were not exposed on the HAp-mixed PLLA fiber surface but covered with the PLLA matrix. A HAp-nanocrystal coating was applied onto the surface of the HAp-mixed PLLA fabric after corona discharge treatment followed by ethanol washing. The submicron-sized dimples were enlarged after the ethanol washing. After the HAp-nanocrystal coating, the HAp-mixed PLLA fabric surface was uniformly coated with the HAp nanocrystals. In vitro cell spread tests showed that the rat osteoblasts spread more on HAp-nanocrystal-coated fabrics than on non-HAp-coated fabrics. Upon covering calvarial defects, the in vivo hard tissue responses suggested earlier restoration of the defects with HAp-nanocrystal-coated fabrics than those with non-HAp-coated fabrics.