Curvature instability in a chiral amphiphile self-assembly.

We present the first experimental evidence for the morphological transition from twisted to helical ribbons in amphiphile aggregates. This transition, from structures possessing negative Gaussian curvature to helically curved structures, is shown to be directly linked to ribbon width. Time-resolved cryotransmission electron microscopy images of a peptidomimetic amphiphile further capture the dynamic transformation between the two geometries along a single ribbon unit. Quantitative analysis indicates that both ribbon width and pitch grow with ribbon maturation, maintaining a constant ratio.