A novel ratiometric fluorescence probe based on the FRET-ICT mechanism for detecting fluoride ions and viscosity.

Fluoride ion is not only important for dental health, but also a contributing factor in a variety of diseases. At the same time, fluoride ions and cell viscosity are both important to the physiological environment of mitochondria. We developed a dual-response ratiometric fluorescent probe BDF based on Förster resonance energy transfer (FRET) and intramolecular charge transfer (ICT) mechanism for the detection of F- and viscosity. BDF has an outstanding intramolecular energy transfer efficiency of 97.7% and shows excellent performance for fluorine ion detection. In addition, when the system viscosity increases, the fluorescence emission intensity of BDF is greatly heightened, indicating the possibility of viscosity detection. Finally, based on the fluorescence properties of BDF, we used the probe to detect F- in the toothpaste sample and image exogenous fluoride ions in HeLa cells.

A spectroscopic probe with FRET-ICT feature for thiophenol monitoring in real water samples.

Thiophenol (PhSH) is widely used in industry, however, it is extremely harmful to the environment and human health due to its high toxicity. In this work, we developed a new FRET-ICT-based ratiometric fluorescent and colorimetric probe (DMNP) for detecting PhSH. DMNP had an ultrahigh energy transfer efficiency (99.7%) and clear spacing of two emission peaks (133 nm). DMNP achieved a fast response to PhSH and exhibited drastic enhancement (over 2100 folds) of the fluorescence intensity ratio upon addition of PhSH. DMNP showed good linear response in the PhSH concentration ranges of 0.5-13 µM and 17.0-22.0 µM. Meanwhile, DMNP could also be applied to monitor PhSH in a variety of real water samples.

A new turn-on fluorescent probe for sensing 4-methylbenzenethiol in real water samples.

A new fluorescent probe (MBT) for the detection of 4-methylbenzenethiol (p-MePhSH) was developed by using 4-(benzo[d]thiazol-2-yl)-3-methoxyphenol as the fluorophore and 2,4-dinitrophenyl ether as the sensing moiety. Probe MBT displayed good selectivity toward p-MePhSH in DMSO/PBS buffer (5/5, v/v) solution and anti-interference over other competitive species via nucleophilic aromatic substitution. The fluorescence intensities of the probe responded p-MePhSH showed a 22-fold enhancement and good linearity with p-MePhSH concentration collected in the range of 0-15 µM. Moreover, the probe is sensitive to p-MePhSH and the limit of detection is 45 nM. The sensing mechanism of probe MBT was verified by high-resolution mass spectrometry and fluorescence lifetime. Furthermore, the probe was used to the detection of p-MePhSH in real water samples.