Fig. 2.

The effect of nanoneedle approach velocity on penetration through the plasma membrane. a Fluorescent microscopy of MCF-7 and HeLa cells. For both cell types, actin and vimentin were stained with rhodamine phalloidin and anti-vimentin antibody visualized with secondary anti-mouse IgG labeled with Alexa 488, respectively. b Set up of a nanoneedle modified with anti-vimentin antibodies via ZZ-BNC, and the detection of fishing force. c Fishing forces detected for MCF-7 and HeLa cells as vimentin-negative and -positive control, respectively. The horizontal line within the box indicates the median, boundaries of the box indicate the 25th- and 75th-percentile, and the whiskers indicate the highest and lowest values of the results. Approach velocity was at 1, 10, or 1000 µm/s, while retracting velocity fixed at 10 µm/s. This measurement was performed at room temperature (25 °C). Plots by small dot and diamond-shaped symbol represent the fishing force and the average fishing force, respectively