(213a) Understanding Hydrophobic Interactions On the Nano-Scale Using Beta-Peptide Oligomers

Helical oligomers of beta-peptides represent a particularly promising type of organic nanostructure for investigations of intermolecular forces because (i) the helical secondary structure can be designed to be very stable and because (ii) control of the beta-amino acid sequence can lead to precise patterning of chemical functional groups over the surfaces of the helices.  This presentation will describe the use of force spectroscopy to quantify the interactions of single beta-peptide oligomers, each of which display stable and well-defined three-dimensional chemical nanopatterns, with hydrophobic surfaces.  Whereas many prior reports of single molecule force measurements of oligo-alpha-peptides and macromolecules exist – the secondary and/or tertiary structures of these species are not preserved during their interactions at interfaces, and thus the three-dimensional chemical patterns that underlie previously reported force measurements are generally not known.   By using beta-peptide oligomers that display the same chemical functional groups in stable and distinct spatial nano-patterns, we have demonstrated that it is possible to relate changes in measured forces to changes in three-dimensional chemical nano-patterns.  Overall, the results to be described in this presentation will show how beta-peptide oligomers can be used to study intermolecular interactions that arise from precisely defined chemical nano-patterns.  A particular focus of the talk will be directed to understanding hydrophobic interactions, thus providing insights into the mechanisms through which changes in chemical patterns presented by organic nanoscopic objects can affect their self-assembly behavior in aqueous environments.