Calcium-Induced Morphological Transitions in Peptide Amphiphiles Detected by ¹⁹F-Magnetic Resonance Imaging

Abstract

Misregulation of extracellular Ca²⁺ can indicate bone-related pathologies. New, noninvasive tools are required to image Ca²⁺ fluxes and fluorine magnetic resonance imaging (¹⁹F-MRI) is uniquely suited to this challenge. Here, we present three, highly fluorinated peptide amphiphiles that self-assemble into nanoribbons in buffered saline and demonstrate these nanostructures can be programmed to change ¹⁹F-NMR signal intensity as a function of Ca²⁺ concentration. We determined these nanostructures show significant reduction in ¹⁹F-NMR signal as nanoribbon width increases in response to Ca²⁺, corresponding to ¹⁹F-MR image intensity reduction. Thus, these peptide amphiphiles can be used to quantitatively image biologically relevant Ca²⁺ concentrations.