MediaChrom: a new class of versatile polarity-sensitive dyes for imaging applications

Modern biological research needs a continuous development of new fluorescent dyes, to be used as markers or probes, characterized by improved performances. These molecules should allow a highly specific and sensitive monitoring for a wide range of biological processes. A particular class of dyes, called environment-sensitive dyes, are able to change their spectroscopical properties in response to the change of physico-chemical features of their environment. Among them, polarity-sensitive dyes (also called solvatochromic dyes) have the unique feature to display a different emission maximum as a function of the environment polarity. This property makes them the ideal probes to monitor the local properties of particular cell districts, as well as different types of biomolecular interactions (e.g., peptide-nucleic acid, protein-protein, and peptide-lipid interactions). Several polarity-sensitive dyes have been developed, but most of them are far to meet simultaneously all the optimal spectroscopic requirements for biological applications, i.e., a strong solvatochromism, absorption in the visible range, high extinction coefficient, high quantum yield, good photostability. We designed a new class of polarity-sensitive dyes, named MediaChrom, that absorb and emit light in the visible range with good extinction coefficient and quantum yield. MediaChrom proved to be highly sensitive to the environment polarity and easily conjugated to proteins and peptides for directing them to defined biological targets.