Development of a Fluorescent Probe for Measurement of Singlet Oxygen Scavenging Activity of Flavonoids.

A turn-on fluorescent probe, HOCD-RB, for monitoring singlet oxygen (O) was developed by linking rhodamine B as fluorophore with dimethylhomoocoerdianthrone (HOCD) as O reaction site and fluorescence quencher due to the intramolecular energy transfer (ET) between rhodamine B and HOCD moieties. Upon exposure to O it rapidly forms endoperoxide with HOCD and turns on the fluorescence of rhodamine B by 18-fold. Taking advantage of the HOCD-RB probe that shows fast response, high sensitivity, and selectivity for O, it is applied for imaging of endogenous O in living cells and the fluorometric assay for evaluating O quenching activity of selected common flavonoids found in our daily diets.

Highly selective and sensitive near-infrared-fluorescent probes for the detection of cellular hydrogen sulfide and the imaging of H2S in mice.

Herein, we report the development of two fluorescent probes for the highly selective and sensitive detection of H2S. The probes take advantage of a Cu(II)-cyclen complex, which acts as a reaction center for H2S and as a quencher of BODIPY (boron-dipyrromethene)-based fluorophores with emissions at 765 and 680 nm, respectively. These non-fluorescent probes could only be turned on by the addition of H2 S, and not by other potentially interfering biomolecules, including reactive oxygen species, cysteine, and glutathione.

Nickel(II) dithiocarbamate complexes containing sulforhodamine B as fluorescent probes for selective detection of nitrogen dioxide.

We synthesized complexes of Ni(II) with dithiocarbamate ligands derived from the ortho and para isomers of sulforhodamine B fluorophores and demonstrated they are highly selective in reactions with nitrogen dioxide (NO2). Compared with the para isomer, the ortho isomer showed a much greater fluorescence increase upon reaction with NO2, which led to oxidation and decomplexation of the dithiocarbamate ligand from Ni(II). We applied this probe for visual detection of 1 ppm NO2 in the gas phase and fluorescence imaging of NO2 in macrophage cells treated with a nitrogen dioxide donor.