The experimental characterization of molecular dynamics (MD) on sub-nanometer length scales, analogous to MD simulations, is needed in order to better design new supramolecular materials, but has presented a longstanding challenge. Herein we overcome this challenge using quantitative electron paramagnetic resonance spectroscopy (EPR) coupled with site-specific spin labeling, and reveal the complexity of dynamics through the 7.6 nm cross-section of a nanofiber self-assembled from peptide amphiphiles. We find that the variation in the internal dynamic structure of the supramolecular nanofiber is dramatic, ranging from solid-like to liquid-like molecular motion across the nanofiber diameter. Further, we identify design parameters by which the internal dynamics may be controlled, and show the significance of varying internal dynamics in the context of supramolecular biomaterials. This characterization strategy serves as a precise analytical tool that may be used to investigate internal conformational dynamics in a wide range of supramolecular assemblies.

Direct measurement of internal dynamics in a self-assembled nanofiber

245th National Meeting (2013)

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