Fig. 5.

Representative force curve obtained over a nanodot in 5% 1,2-hexanediol. (A) The lack of a repulsive force on approach (red symbols) signifies that the entropic barrier has collapsed. Upon retraction (blue symbols), a cNup153 molecule remains bound to the AFM tip and unbinds at D ≈ 130 nm. A WLC fit gives l_p = 0.5 nm for this curve (boxed). The double-headed arrow denotes the range over which the relative stiffness was calculated. The position of the force measurement (black triangle) above the nanodot is indicated in the quasitopographic image shown in the Inset. (Scale bar, 50 nm.) (B) Corresponding stiffness map showing that the relative stiffness (color-coded in the scale bar) is ≈0.02 N/m over the entire area (i.e., the entropic barrier has collapsed). The values along the figure axes are in nanometers. This stiffness map is also similar to control measurements made in the absence of cNup153 (see text).