12-Hydroxystearic acid lipid tubes under various experimental conditions

Area of Science:

• Supramolecular chemistry
• Materials science
• Physical chemistry

Background:

• Amphiphilic molecules are of interest for constructing supramolecular hollow tubes.
• Aqueous solutions of 12-hydroxystearic acid ethanolamine salt form temperature-tunable tubes.
• The phase behavior of this system requires further investigation.

Purpose of the Study:

• To investigate the effects of various physico-chemical parameters on the self-assembly of 12-hydroxystearic acid ethanolamine salt.
• To determine the conditions under which hollow tubes form.
• To explore the potential of using low-cost fatty acids for self-assembly.

Main Methods:

• Phase-contrast microscopy was used to observe tube formation.
• Differential Scanning Calorimetry (DSC) was employed to study phase behavior.
• Systematic variation of parameters including ionic strength, ethanol concentration, lipid doping, pH, concentration, and molar ratio (R) was performed.

Main Results:

• Hollow tubes were observed to form under a wide range of experimental conditions.
• The fatty acid/ethanolamine molar ratio (R) could be varied from 2/3 to 5/2 without preventing tube formation.
• Tube diameter showed temperature dependence in some, but not all, tested conditions.

Conclusions:

• Supramolecular hollow tubes can be formed from 12-hydroxystearic acid ethanolamine salt under diverse experimental conditions.
• The self-assembly process is robust with respect to variations in ionic strength, pH, and molar ratio.
• These findings highlight the potential for utilizing cost-effective fatty acids in the production of self-assembled nanostructures.