Self-Assembly of Peptide-Containing Mesogens: Thermotropic Liquid-Crystalline Properties and Macroscopic Alignment of Amphiphilic Bioconjugates

Thermotropic liquid crystals having tripeptide moieties are reported. A series of peptide chains including arginine-glycine-aspartic acid (RGD), glycine-glycine-aspartic acid (GGD), and triglycine (GGG) moieties is connected to a rigid-rod core through a flexible tetraoxyethylene spacer. These bioconjugated mesogens form intermolecular hydrogen bonds through amide groups in the tripeptide moieties. It is found that side chains in the tripeptide-conjugated mesogens constrain intermolecular hydrogen bonding in the bulk states, which affects the formation of the liquid-crystalline phases. The rigid-rod mesogens bearing RGD and GGD peptide sequence exhibit smectic phases with high thermal stability of the mesophases. The liquid-crystalline assemblies of the mesogen-containing peptides are macroscopically oriented by mechanical shearing. The present design of bioconjugated liquid crystals could lead to the development of new self-assembled materials for biological applications.