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Orientational Transition in a Liquid Crystal Triggered by the Thermodynamic Growth of Interfacial Wetting Sheets
Published on: May 15, 2017
Lyotropic liquid crystals from designed helical beta-peptides.
William C Pomerantz1, Nicholas L Abbott, Samuel H Gellman
1Departments of Chemical and Biological Engineering and Chemistry, University of Wisconsin, Madison, Wisconsin 53706, USA.
Journal of the American Chemical Society
|July 6, 2006
Summary
Short beta-peptides form liquid crystalline phases in water. These self-assembling molecules offer a new basis for designing advanced liquid crystal materials.
Area of Science:
- Biomolecular self-assembly
- Supramolecular chemistry
- Materials science
Background:
- Beta-peptides are peptide chains with a backbone containing an additional carbon atom compared to alpha-peptides.
- Self-assembly of peptides into ordered structures is a key area in biomaterials research.
- Liquid crystalline (LC) phases exhibit properties between those of conventional liquids and solid crystals.
Purpose of the Study:
- To investigate the potential of 14-helical beta-peptides to form lyotropic liquid crystalline (LC) phases in aqueous solutions.
- To determine the structural requirements for beta-peptide-induced LC phase formation.
- To assess the thermal stability and reversibility of these beta-peptide-based LC phases.
Main Methods:
- Design and synthesis of a series of 14-helical beta-peptides with varying lengths.
- Optical microscopy to observe and characterize liquid crystalline phase formation.
- Variable temperature Deuterium Nuclear Magnetic Resonance (2H NMR) spectroscopy to assess thermal stability.
- Assessment of concentration and net charge effects on LC behavior.
Main Results:
- Four designed beta-peptides self-assembled into lyotropic liquid crystalline phases at low concentrations (2.5 wt %).
- A scrambled beta-peptide sequence did not form LC phases, indicating the importance of a globally amphiphilic helical conformation.
- The LC phase formed by beta-peptide 3 was thermally reversible, disrupting above 40°C and reforming upon cooling.
- LC phase behavior was influenced by concentration and net charge.
Conclusions:
- 14-helical beta-peptides can form lyotropic liquid crystalline phases in water.
- Globally amphiphilic conformation is crucial for beta-peptide-induced liquid crystallinity.
- Beta-peptide-based LC phases exhibit thermal reversibility and can be tuned by concentration and charge.
- These findings suggest beta-peptides can form LC phases at shorter lengths than alpha-peptides, offering new avenues for materials design.
