Reversible transitions between peptide nanotubes and vesicle-like structures including theoretical modeling studies.

Peptide-based self-assembling systems are increasingly attractive because of their wide range of applications in different fields. Peptide nanostructures are flexible with changes in the ambient conditions. Herein, a reversible shape transition between self-assembled dipeptide nanotubes (DPNTs) and vesicle-like structures is observed upon a change in the peptide concentration. SEM, TEM, AFM, and CD spectroscopy were used to follow this transition process. We show that dilution of a peptide-nanotube dispersion solution results in the formation of vesicle-like structures, which can then be reassembled into the nanotubes by concentrating the solution. A theoretical model describing this shape-transition phenomenon is presented to propose ways to engineer assembling molecules in order to devise other systems in which the morphology can be tuned on demand.