Regulation of Fluorescence Solvatochromism To Resolve Cellular Polarity upon Protein Aggregation

Common solvatochromic fluorophores exhibit a bathochromic fluorescence emission wavelength shift accompanied by intensity attenuation due to the presence of nonradiative decay pathways at the excited state. Such intrinsic but inevitable fluorescence quenching of solvatochromism impedes its applications to faithfully quantify local polarity, especially in a polar environment. Herein, we report a new donor-π-acceptor (D-π-A) type solvatochromic fluorophore scaffold containing a perfluorophenyl group that exhibits both a solvatochromic emission wavelength shift and a controllable emission intensity upon polarity fluctuation. The regulation of fluorescence solvatochromism and colors was achieved by tuning the aryl donors. We exploited such desired solvatochromism of these probes to monitor protein misfolding and aggregation via wavelength shift. Finally, the polarity of pathogenic aggregated proteins was quantified by HaloTag bioorthogonal labeling technology in live cells. While much effort has been devoted to resolving the morphology of pathogenic aggregated proteins, this work provides quantitative hints regarding the chemical information at this disease-related protein interphase.