Deyan Gong

A fluorescence enhancement probe based on BODIPY for the discrimination of cysteine from homocysteine and glutathione.

Herein, a fluorescent probe BODIPY-based glyoxal hydrazone (BODIPY-GH) (1) for cysteine based on inhibiting of intramolecular charge transfer (ICT) quenching process upon reaction with the unsaturated aldehyde has been synthesized, which exhibits longer excitation wavelength, selective and sensitive colorimetric and fluorimetric response toward cysteine in natural media. The probe shows highly selectivity towards cysteine over homocysteine and glutathione as well as other amino acids with a significant fluorescence enhancement response within 15min In the presence of 50 equiv. of homocysteine, the emission increased slightly within 15min and completed in 2.5h to reach its maximum intensity. Therefore, the discrimination of cysteine from homocysteine and glutathione can be achieved through detection of probe 1. It shows low cytotoxicity and excellent membrane permeability toward living cells, which was successfully applied to detect and image intracellular cysteine effectively by confocal fluorescence imaging.

A Phenylselenium-Substituted BODIPY Fluorescent Turn-off Probe for Fluorescence Imaging of Hydrogen Sulfide in Living Cells

Herein a phenylselenium-substituted BODIPY (1) fluorescent turn-off sensor was developed for the purpose to achieve excellent selectivity and sensitivity for H2S detection based on the substitution reaction of the phenylselenide group at the 3-position with H2S. The excess addition of hydrogen sulfide promoted further substitution of the phenylselenide group at the 5-position of the probe and was accompanied by a further decrease in fluorescence emission intensity. Sensor 1 demonstrated remarkable performance with 49-fold red color fluorescence intensity decrease at longer excitation wavelength, a low detection limit (0.0025 μM), and specific fluorescent response toward H2S over anions, biothiols, and other amino acids in neutral media. It showed no obvious cell toxicity and good membrane permeability, which was well exploited for intracellular H2S detection and imaging through fluorescence microscopy imaging.

Fast and Selective Two-Stage Ratiometric Fluorescent Probes for Imaging of Glutathione in Living Cells

Two fluorescent, m-nitrophenol-substituted difluoroboron dipyrromethene dyes have been designed by nucleophilic substitution reaction of 3,5-dichloro-4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY). Nonsymmetric and symmetric probes, that is. BODIPY 1 (with one nitrophenol group at the position 3) and BODIPY 2 (with two nitrophenol groups at the positions 3 and 5) were applied to ratiometric fluorescent glutathione detection. The detection is based on the two-step nucleophilic aromatic substitution of the nitrophenol groups of the probes by glutathione in buffer solution containing CTAB. In the first stage, probe 1 showed ratiometric fluorescent color change from green (λem = 530 nm) to yellow (λem = 561 nm) because of monosubstitution with glutathione (I561nm/I530nm). Addition of excess glutathione caused the second stage of ratiometric fluorescent color change from yellow to reddish orange (λem = 596 nm, I596nm/I561nm) due to disubstitution with glutathione. Therefore, different concentration ranges of glutathione (from less to excess) could be rapidly detected by the two-stage ratiometric fluorescent probe 1 in 5 min. While, probe 2 shows single-stage ratiometric fluorescent detection to GSH (from green to reddish orange, I596nm/I535nm). Probes 1 and 2 exhibit excellent properties with sensitive, specific colorimetric response and ratiometric fluorescent response to glutathione over other sulfur nucleophiles. Application to cellular ratiometric fluorescence imaging indicated that the probes were highly responsive to intracellular glutathione.

BODIPY-based fluorescent sensor for imaging of endogenous formaldehyde in living cells

A new highly selective fluorescent chemosensor for formaldehyde (FA) has been synthesized based on boron dipyrromethene as fluorophore and o-phenylenediamine (OPDA) as reaction group. When FA is added, the fluorescence emission band of the chemosensor red shift (from 525 nm to 548 nm) accompanied by an increase in intensity with strong green fluorescence was observed. This chemosensor also exhibited the lowest detection limit (0.104 μM) distinguished with other articles that have been reported. The application to cellular fluorescence imaging or test papers detection both indicated that the probe was highly responsive to the FA in endogenous cells and in the gaseous environment.