Culture of HeLa cells on RT nanosheets. (A) Time-lapse phase-contrast images of HeLa cells on a RT nanosheet. Images at the onset of culture (left), and at 12 (middle) and 24 h (right) are shown. See Video 3. (B) Live/dead assay for HeLa cells on a culture dish (left) and a RT nanosheet (right) after the 3-d culture. Fluorescence of Calcein and that of DAPI (white arrows) indicate live and dead cells, respectively. (C) Comparison of variability of HeLa cells cultured on culture dishes (gray) and RT nanosheets (pink). Number of cells, 1,453 and 1,420 on culture dishes and RT nanosheets, respectively. n = 4. The Mann–Whitney U test was performed. n.s., not significant.