Fig. 2.

Tapping-mode AFM images reveal filamentous polymers and fibrils (nanoropes). Samples were prepared by using 144 μM peptide and 10 mM Tris·HCl, pH 8.0. (a) Phase image of nanofilaments formed in 1.5 M NaCl. (b) Topography image of nanofilaments formed in 0.75 M (NH₄)₂SO₄; z-scale, 25 nm. The nanofilaments are much longer than those in a and show greater tendency to associate. (c) Phase image showing the same area and magnification as in b. The internal structure is better resolved in the phase images.