Thiomaleimide Functionalization for Selective Biological Fluorescence Detection of Peroxynitrite as Tested in HeLa and RAW 264.7 Cells

The role of fluorescent molecules in diagnosis, treatment as well as in biomedical research has great current medicinal significance and is the focus of concentrated effort across the scientific research spectrum. Related research continues to reveal new practical sensing systems that bear enhanced features for interfacing of substituted molecules with biological systems. As part of an effort to better understand chalcogenide systems, a new dithiomaleimide BODIPY (BDP‐NGM) probe has been designed, synthesized and characterized. The fluorescence of BDP‐NGM was quenched by the incorporation of [3,4‐bis(phenylthio)] on the maleimide‐4‐phenyl moiety which is, in turn, placed at the meso‐position of the BODIPY system. The probe shows a turn‐on fluorescence response upon reaction with ONOO−; mass spectral evidence reveals peaks in agreement with products involving oxidation of the sulfur groups to sulfone groups. An about 18.0‐fold emission intensity enhancement was found. By comparison, the emission signal from another ROS/RNS, superoxide, gave a modest turn on signal (≈5.0‐fold). The reaction is complete within 10 min, judging from the monitoring of the turn‐on fluorescence process; the detection limit was found to be 0.4 μm. BDP‐NGM can be used for the detection of ONOO− under both acidic and basic conditions. Live cell imaging showed that the current probe can be used for the selective detection of ONOO− in living systems. What a response! A dithiomaleimide BODIPY (BDP‐NGM) turn‐on fluorescence probe for the selective detection of peroxynitrite over other competing reactive oxygen and nitrogen species (ROS/RNS) is reported. The BDP‐NGM probe showed a selective and sensitive turn‐on response with endogenous peroxynitrite in live HeLa and RAW264.7 cells, as confirmed by confocal microscopy imaging.