Apatite-forming ability of bioactive poly(l-lactic acid)/grafted silica nanocomposites in simulated body fluid.

Bioactive PLLA/surface-grafted silica (g-SiO₂) nanocomposite scaffolds were fabricated by solid-liquid phase separation method. And solid PLLA/g-SiO₂ nanocomposite films were prepared by solution casting method. A series of parallel tube-like morphology and internal ladder-like structure of PLLA/g-SiO₂ nanocomposite scaffolds were observed by SEM. The formation of bone-like apatite in the simulated body fluid (SBF) was characterized by XRD, IR, SEM, EDS and weight measurement. The silica incorporation favors the formation of apatite. The growth of apatite with immersion time is found on the surfaces of both the PLLA/g-SiO₂ nanocomposite scaffolds and the films. The potential mechanism is that silanol groups of g-SiO₂ in the nanocomposites serve as nucleation sites for the formation of bone-like apatite crystals.