Enantioselective Interaction between Cells and Chiral Hydroxyapatite Films

The enantioselective interactions between cells and chiral materials would be a crucial factor in homochiral organisms. Herein, we report that pure inorganic chiral mesostructured hydroxyapatite films (CMHAPFs) exhibit enantioselectivity in the regulation of cell behaviors. CMHAPFs were fabricated with tartaric acid (TTA) as a symmetry-breaking agent, and five levels of fractal-like chirality existed: primary twisted “nanoneedles” with atomically distorted crystal lattices, secondary “nanoflakes” with a helical arrangement of “nanoneedles”, tertiary “nanoplates” with a helical arrangement of “nanoflakes”, quaternary “nanopetals” with a helical arrangement of “nanoplates”, and quinary “flowers” consisting of helically arranged “nanopetals”. The CMHAPFs synthesized with L-TTA were advantageous in cell adhesion, cell proliferation, and osteogenic differentiation of primary mesenchymal stem cells, whereas the opposite effect was observed in the CMHAPFs synthesized with D-TTA. This enantioselectivity was speculated to be due to the stereo matching between the hierarchical chiral cell surfaces and multilevel chiral mesostructures of CMHAPFs.