Analyte-Driven Disassembly and Turn-On Fluorescent Sensing in Competitive Biological Media.

Many indicator displacement assays can detect biological analytes in water, but these often have reduced performance in the presence of an unavoidable component: NaCl. We report here a new self-assembled sensor, DimerDye, that uses a novel photochemical guest-sensing mechanism and that is intrinsically tolerant of cosolutes. We synthetically integrated a dye into a calixarene macrocycle, forming two new merocyanine calixarenes (MCx-1 and MCx-2). Both compounds self-assemble into nonemissive dimers in water. The addition of good guests like trimethyllysine induces a turn-on fluorescence response of MCx-1 due to simultaneous dimer dissociation and formation of an emissive host-guest complex. DimerDyes remain functional in solutions containing the various salts, metal ions, and cofactors that are needed for enzymatic reactions. MCx-1 provides a real-time, turn-on fluorescence signal in response to the lysine methyltransferase reaction of PRDM9.