Fig. 6: Muscle cell differentiation on different PC substrates.

a Optical microscopic images of differentiated C2C12 myoblasts at the 10th day after cell seeding on the CD-R, DVD-R, BD-R, and flat PC surfaces. The directions of the nanogrooved patterns are marked by solid arrows, while the directions of the myotubes on the surfaces are marked by dotted arrows. b Average width and length of myotubes that grew on the corresponding PC substrates. Error bars represent the SD (n = 400 myotubes). c Average number of myotubes cultured on the corresponding PC substrates. Error bars represent the SD (n = 1638 myotubes). d Average width, length, and elongation of the cell nucleus in myotubes that grew on the corresponding PC substrates. Error bars represent the SD (n = 400 nuclei). e Fusion index and maturation index for myoblasts differentiated on the corresponding PC substrates. Error bars represent the SD (n = 971 myotubes). *P < 0.05, ***P < 0.001, compared to the flat PC substrate. Data are results from 3 independent experiments. f Fluorescence images of myotubes differentiated for 5 days on flat and nanogrooved (groove width: 100 nm; ridge width: 200 nm; ridge height: 20 nm) PC surfaces. Myosin was stained green, while the cell nucleus was stained blue. g Orientations of myotubes that initiated their differentiation on the nanogrooved/flat PC substrates for 3 and 7 days