Novel triphenylamine-based fluorescent chemo-sensors for fast detection of thiophenols in vitro and in vivo

Two red/blue-emitting fluorescent probes for quick, portable, and selective detection of thiophenol in food, soil and plant samples, and their applications in bioimaging

Thiophenol (PhSH), which is widely used in many industries, poses significant health risks owing to its acute toxicity and irritating effects. Thus, the detection of PhSH is crucial for ensuring environmental and food safety. There is significant room for improvement in the sensing properties of the reported analytical methods, such as response time, detection limit, selectivity, and portable detection. Herein, we present two new red/blue fluorescence-emissive sensors (NS1 and NS2) for PhSH detection. After reacting with PhSH, NS1 exhibited a low detection limit (66.7 nM), red emission, fast response time of just 10 s, and large Stokes shift (240 nm). NS2 could detect PhSH with a low detection limit (75.8 nM), fast response time of 20 s, and blue emission. The noticeable color response and portability of the two probes made them suitable for on-site detection of PhSH in various samples, such as water, soil, plant, food samples, and living cells. Moreover, it has been shown that these probes could be used to determine PhSH content in smartphone applications, thin layer chromatography kits, and polysulfone capsule kits. Prepared probes have low cytotoxicity and show good permeability in tested living cells, which is important for early diagnosis, disease research, and emergency analysis. Compared with other studies, the proposed approach has remarkable advantages in terms of detection limit, portability, response time, and low cytotoxicity. Thus, it meets the crucial demand for ensuring health, environmental and food safety, and adherence to regulatory standards.

Vinyl substituted triphenylamine based turn-off fluorescent probe for selective and sensitive detection of mercury (II) in water and live cells

Here, we report vinyl substituted triphenylamine (TPA-alk) fluorescent probe for the rapid and efficient detection of mercury ion (Hg²⁺) in water and biological environment. TPA-alk detects Hg²⁺ selectively over a wide range of competitive metal ions with a blue shift of 43 nm in the UV absorbance spectrum. The detection limit is found to be 0.146 µM (29.2 ppb) with high selectivity over a wide range of competitive metal ions. DFT study explains the blue shift in the UV-vis absorption band of the optical probe upon the addition of Hg²⁺. Cell viability assay illustrates that the probe is biocompatible and it has low cytotoxicity even at its higher concentration. Cell imaging studies demonstrate the efficiency of the TPA-alk probe for the micromolar detection of mercury (II) in live BMG1 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 ratiometric fluorescent probe for selective detection of thiophenol derivatives

Though a number of on-off or off-on fluorescent probes have been developed for the detection of thiophenol by using its unique recognition groups, such as 2, 4-dinitrophenyl ether, 2, 4-dinitrophenyl sulfonamide, and 2, 4-dinitrophenyl sulfonate, up to now, there are few probes that can detect thiophenol by the proportional fluorescence signal. We developed a ratiometric fluorescent probe with coumarin pyridine derivative as fluorophore and 2, 4-dinitrophenyl ether moiety as the sensing unit which could be used to detect thiophenol derivatives by the aromatic nucleophilic substitution reaction. This probe (CPBPN) displayed significant change in fluorescence ratio (256 fold) to result in a more reliable analysis by self-calibration and a relatively low detection limit of 24 nM toward 4-methylthiophenol (MTP) within 30 min to achieve more sensitivity. Besides, the probe was also applied to detect the presence of thiophenol derivatives in actual water samples and fluorescence imaging in living cells. The present work is of great importance for monitoring environmental pollutants and studying their biological function.

Triphenylamine-based small-molecule fluorescent probes

Ammonia with the three hydrogens substituted by phenyls is known as triphenylamine (TPA), and is one of the most useful compounds because of its vast practical applications. Chemists have produced thousands of TPA derivatives to date. Because of its biocompatibility and structural features, it has been widely used in the fields of molecular recognition, molecular imaging, materials chemistry, and also in biology and medical science. Its strong electron-donating ability encourages scientists to produce different types of probes for molecular recognition. This review is based on recent developments and advances in TPA-based small molecular fluorescent probes within the time period 2010-2021. This extensive review may expedite improvements in more advanced fluorescent probes for vast and stimulating applications in the future.

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.