Self-assembly of amphiphiles with terthiophene and tripeptide segments into helical nanostructures

Wei Wen Tsai, Liang shi Li, Honggang Cui, Hongzhou Jiang, Samuel I. Stupp*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

62 Scopus citations

Abstract

We previously reported a class of tripeptide amphiphiles known as peptide lipids that self-assemble into one-dimensional nanostructures with superhelical twisting. The pitch of this supramolecular twisting is controlled directly through sterics in the molecular structure of hydrophobic segments. In this work we study the supramolecular behavior of these nanoscale helices by substituting with a terthiophene conjugated segment of potential electronic interest and also through variations in the stereochemistry of the tripeptide. This terthiophene peptide lipid was shown to self-assemble into one-dimensional helical nanofibers with a regular diameter of 9±1 nm and helical pitch of 65±6 nm, and also found to form hierarchical double- and triple-stranded helices, which could be associated with terthiophene J-aggregate interactions among fibers. For stereochemical effects, we compared four diastereomers in the tripeptide sequence using l-glutamic acid and l- and d-alanine residues to probe their ability to control supramolecular organization. Interestingly, we found by atomic force microscopy that the LLD diastereomers formed cylindrical nanofibers without any twisting, whereas LDD diastereomeric segments self-assembled into helical nanofibers with a pitch of 40±6 nm. LDL diastereomeric segments formed, on the other hand, aggregates without any regular shape. We propose that these profound effects of chirality with amino acid sequence are related to changes in the β-sheet sub-structure within the nanofibers.

Original languageEnglish (US)
Pages (from-to)8504-8514
Number of pages11
JournalTetrahedron
Volume64
Issue number36
DOIs
StatePublished - Sep 1 2008

Keywords

  • Helical nanostructure
  • Self-assembly
  • Stereochemistry
  • Terthiophene

ASJC Scopus subject areas

  • Biochemistry
  • Drug Discovery
  • Organic Chemistry

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