Unraveling the mechanism of nanotube formation by chiral self-assembly of amphiphiles

Lior Ziserman, Hee Young Lee, Srinivasa R. Raghavan, Amram Mor, Dganit Danino*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

186 Scopus citations

Abstract

The self-assembly of nanotubes from chiral amphiphiles and peptide mimics is still poorly understood. Here, we present the first complete path to nanotubes by chiral self-assembly studied with C12- β12 (N-α-lauryl-lysyl-aminolauryl-lysyl-amide), a molecule designed to have unique hybrid architecture. Using the technique of direct-imaging cryo-transmission electron microscopy (cryo-TEM), we show the time-evolution from micelles of C1212 to closed nanotubes, passing through several types of one-dimensional (1-D) intermediates such as elongated fibrils, twisted ribbons, and coiled helical ribbons. Scattering and diffraction techniques confirm that the fundamental unit is a monolayer lamella of C1212, with the hydrophobic tails in the gel state and β-sheet arrangement. The lamellae are held together by a combination of hydrophobic interactions, and two sets of hydrogen-bonding networks, supporting C1212 monomers assembly into fibrils and associating fibrils into ribbons. We further show that neither the "growing width" model nor the "closing pitch" model accurately describe the process of nanotube formation, and both ribbon width and pitch grow with maturation. Additionally, our data exclusively indicate that twisted ribbons are the precursors for coiled ribbons, and the latter structures give rise to nanotubes, and we show chirality is a key requirement for nanotube formation.

Original languageEnglish
Pages (from-to)2511-2517
Number of pages7
JournalJournal of the American Chemical Society
Volume133
Issue number8
DOIs
StatePublished - 2 Mar 2011
Externally publishedYes

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