Superresolution Imaging of Photochromic Acylhydrazone Moieties on Amyloid Nanofibrils: Implications for Photoswitchable Probes

We report the incorporation of salicylaldehyde derivatives onto the hydrazine-tagged amyloidogenic peptides by forming photoisomerizable hydrazones. These hydrazones with positive photochromism are photostable under physiological conditions and enable photoswitching without the addition of external reductants or high-power irradiation. By applying super-resolution microscopy, we were able to distinguish polymorphic nanoscopic structures of the hydrazone-incorporated peptides in vitro under different buffer conditions. Moreover, the additive-free condition in our platform allows the exploration of detailed amyloid aggregate morphologies in live cells.