Nano-hydroxyapatite promotes self-assembly of honeycomb pores in poly(L-lactide) films through breath-figure method and MC3T3-E1 cell functions

Recently, honeycomb-patterned polymeric films have been fabricated through breath-figure method to mimic the topographical feature of the basement membrane and this topography was demonstrated to enhance osteoblast functions including adhesion, spreading, proliferation, and differentiation. However, honeycomb-patterned films incorporated with other components benefiting osteoblast functions have not been reported yet. In this study, we report the fabrication of nano-hydroxyapatite (nHA) (3 wt%, 5 wt%, and 7 wt%) incorporated honeycomb poly(L-lactide) (PLLA) films to evaluate the effect of nHA on the self-assembly of honeycomb pores in PLLA films. Scanning electron microscopy (SEM) images demonstrated that 5 wt% nHA in PLLA resulted in the most regular honeycomb pores. Water contact angle test and protein adsorptions including fibronectin (FN) and serum were performed on 5 wt% nHA incorporated honeycomb PLLA films (H-PLLA/nHA), as well as the controls, flat PLLA films (F-PLLA), honeycomb PLLA films (H-PLLA), and flat HA films (F-HA). Honeycomb pores in H-PLLA films enhanced hydrophobicity compared with F-PLLA films, whereas nHA particles in H-PLLA/nHA films lowered the hydrophobicity compared with H-PLLA. Both the FN and serum protein adsorptions were increased on H-PLLA films compared with F-PLLA, but decreased significantly on H-PLLA/nHA films compared with H-PLLA films. Further, MC3T3-E1 mouse newborn calvaria preosteoblasts were employed to investigate the cell functions in terms of cell adhesion, spreading, proliferation, and differentiation on those films. The results strongly indicated that those cell functions were promoted on honeycomb films, especially H-PLLA/nHA films, compared with F-PLLA films and they did not show a significant difference between H-PLLA films and F-HA films.