Biological Imaging with Medium‐Sensitive Bichromatic Flexible Fluorescent Dyes

Abstract A family of environment‐sensitive shape‐shifting molecules have been developed as flexible fluorescent (FlexFluor) dyes for biological imaging applications. These compounds feature a flexible bithiophene‐based fluorophore that gives rise to different emission colors in lipophilic or hydrophilic environments, as well as side groups that can be synthetically modified with ease. FlexFluor dyes are the first fluorescent dyes in which emission color can be used to indicate lipid/water environments. The behavior of these dyes in different solvents was studied, and used to simultaneously highlight lipid and water contents in adipose and brain tissues using optical fluorescence microscopy.