Self-Assembly and Associated Photophysics of Dendron-Appended Peptide-π-Peptide Triblock Macromolecules

5 years ago

Self-Assembly and Associated Photophysics of Dendron-Appended Peptide-π-Peptide Triblock Macromolecules

Jeannette E. Marine, John D. Tovar, Tejaswini S. Kale

Peptide-π-peptide triblock molecules can self-assemble into 1-D nanostructures with extensive hydrogen-bonding networks under appropriate pH conditions. These materials are of interest due to the embedded π-electron units that can facilitate energy and charge transport within biocompatible peptide matrices. Interactions among amino acid residues presented along these hydrogen-bonded structures lead to hierarchical bundling into larger fibrillar assemblies. This complicates the analysis of individual fibrils, an understanding of which is important for tailoring the functionality of the resulting nanomaterials. Appending large bulky groups onto the peptides should frustrate these bundling interactions and significantly alter the self-assembly behavior by restricting the formation of higher order assemblies. Here we evaluate the self-assembly behavior of peptide-π-peptide molecules appended with poly(alkyl ether) dendrons containing tetraethylene glycol functionalities. These dendrons render the peptide–dendron hybrid (PDH) molecules incapable of assembly under conditions that typically promote assembly of the parent peptides. However, 1,1,1,3,3,3-hexafluoro-2-propanol, a fluorinated alcohol known to denature proteins, triggers the aqueous assembly of the PDH molecules, thus yielding platelike nanostructures with narrow size distributions. This presents a new methodology for generating self-assembled nanostructures from peptide-π-peptide materials and provides an opportunity for orthogonal functionalization using motifs with varying degrees of hydrophilicity and functions. The effects of peptide sequence and dendron position along the peptide backbone on the assembly behavior were investigated using UV–vis, photoluminescence, and circular dichroism spectroscopies, and the morphologies of the resulting self-assembled nanostructures were investigated using transmission electron microscopy.

Publisher URL: http://dx.doi.org/10.1021/acs.macromol.7b00821

DOI: 10.1021/acs.macromol.7b00821