Tunable Self-Assembled Peptide Amphiphile Nanostructures

摘要

Peptide amphiphiles are capable of self-assembly intona diverse array of nanostructures including ribbons, tubes, andnvesicles. However, the ability to select the morphology of thenresulting structure is not well developed. We examined the influencenof systematic changes in the number and type of hydrophobic andnhydrophilic amino acids on the self-assembly of amphiphilicnpeptides. Variations in the morphology of self-assembled peptidesnof the form X6Kn (X = alanine, valine, or leucine; K = lysine; n = 1−5)nare investigated using a combination of transmission electronnmicroscopy and dynamic light scattering measurements. Thensecondary structures of the peptides are determined using circularndichroism. Self-assembly is controlled through a combination of interactions between the hydrophobic segments of the peptidenmolecules and repulsive forces between the charged segments. Increasing the hydrophobicity of the peptide by changing X tona more lipophilic amino acid or decreasing the number of hydrophilic amino acids transforms the self-assembled nanostructuresnfrom vesicles to tubes and ribbons. Changes in the hydrophobicity of the peptides are reflected in changes in the critical micellenconcentration observed using pyrene probe fluorescence analysis. Self-assembled materials formed from cationic peptidenamphiphiles of this type display promise as carriers for insoluble molecules or negatively charged nucleic acids in drug or genendelivery applications.