Aqueous Self-Assembly of Unsymmetric Peptide Bolaamphiphiles into Nanofibers with Hydrophilic Cores and Surfaces

Abstract
Unsymmetric peptide bolaamphiphiles that incorporate (l-glutamyl)3glycine at one terminus and either tetraethylene glycol or aspartic acid at the other were found to form hydrogels at low wt %, presumably by self-assembling into nanofibers presenting (l-glutamyl)3glycine at their surfaces and burying the second headgroup at their cores. Transmission electron microscopy measurements on 1 wt % gels negatively stained with phosphotungstic acid and positively stained with uranyl acetate show one-dimensional objects with diameters of 5 nm and lengths in excess of 1 μm. Circular dichroism and solid-state FTIR spectra indicate the adoption of β-sheet structure within the nanofibers.