Fig. 2.

Mineralization of ELR membranes. (A) SEM images of a hierarchical mineralized structure grown on a smooth ELR membrane. Mineralized structures grown on the top of ELR membranes with (B) circular-, (C) hexagon-, and (D) star-shaped post topographies. Insets in B and C show non-mineralized circular and hexagonal topographies. Panel E highlighting the different co-alignment between apatite nanocrystals growing on the vertical side of the post (red arrow) and at the junction between the vertical side of the post and the horizontal space between them (white arrow). (F) Graph summarizing the relation between channel dimension and aspect ratio of the mineralized structures grown on patterned ELR membranes. Solid bars correspond to the aspect ratio of visual distance, and striped bars correspond to aspect ratio of growing distance. (G) Cross-section of a microchannel topography highlighting different geometrical spaces within the ELR matrix defined by the topographies including 90°, 180°, and 270° angles. (H) Illustration depicting a mineralized structure with actual and virtual distances traveled by the nanocrystals. (I) SEM images of spherulitic mineralized structures growing on different microchannel dimensions exhibiting different levels of elongation.