Fig. 4

a Optical microscopy images of PC12 cells on nFH-coated surfaces observed for 96 h with 24 h intervals.; Tissue culture grade polystyrene (TCPS) bare surface, 1.0 wt% drop-coated, 0.1 wt% and 1.0 wt% bar-coated nFH surfaces (Scale bar, 100 μm). The aspect ratio of PC12 cells on nFH coated surfaces at b 24 h and c 72 h after cell seeding (n = 100). Trajectories of PC 12 cells cultured on d 1.0 wt% drop-coated, e 0.1 wt% and f 1.0 wt% bar-coated nFH substrates (see the experimental for the details). g Schematics of definitions of migration length and detour ratio. h Migration length and i detour ratio of PC 12 cells on three different substrates