Efficient Modulation of β-Amyloid Peptide Fibrillation with Polymer Nanoparticles Revealed by Super-Resolution Optical Microscopy.

β-Amyloid peptide (Aβ) aggregation is the essential hallmark of neurodegenerative disorders such as Alzheimer's disease. Efficient inhibitors are highly desired for the prevention of Aβ assembly that has been considered as the primary therapeutic strategy for neurodegenerative diseases. Apart from this, visualization of the aggregates and morphology at high spatial resolution is widely considered of crucial significance on biological treatment. In this work, we have developed small-sized (with diameter of ∼4.7 nm) and positively charged fluorescent conjugated polymer nanoparticles (CPNPs) with strong inhibition effect on Aβ1-40 peptides fibrillation. Interestingly, the CPNPs also possess excellent photophysical properties, including high photon counts, robust blinking, and repetitive fluorescence switching, that are especially suitable for localization-based super-resolution imaging. Spatial resolution of ∼20 nm for these blinking CPNPs is readily achieved. According to the optical microscopic results, it was found that binding of CPNPs to the terminal of seed fibrils can effectively inhibit the fibrillation process. Owing to these attractive biological and unique photophysical properties, the small-sized CPNPs show high potential in a variety of super-resolution based biological applications.