Search

A novel ratiometric fluorescence probe for hypochlorous acid was constructed by coumarin and pyridinium fluorophore based on the Forster resonance energy transfer (FRET) and intramolecular charge transfer (ICT) platform. In this ICT/FRET system, the energy transfer efficiency is high to 94.3%. Moreover, the probe could respond to hypochlorous acid with high selectivity and sensitivity, and exhibited a large Stokes shift. It was interesting to find that the probe could recognize hypochlorous acid via a new mechanism, in which the α-position of carbonyl group was oxidized to form a diketone derivative. More importantly, the probe was successfully applied to the ratiometric imaging of both exogenous and endogenous hypochlorous acid in living RAW 264.7 cells, with low toxicity and high photo-stability. Image 1 • A ratiometric fluorescent probe ZPAC for rapidly monitoring hypochlorous acid. • A new mechanism, α position of carbonyl group was oxidized to form a diketone derivative. • FRET-based ZPAC displayed larger gap between two emission spectrum. • ZPAC was applied to image exogenous and endogenous hypochlorous acid in living RAW264.7 cells. [ABSTRACT FROM AUTHOR]

Cyanide detection methods are urgently needed due to the highly lethal to human beings. Herein, we report two fluorescence probes (Probe 1 and Probe 2) based on cyanoethylene group for cyanide anion (CN−) detection. The selective recognition for CN− was confirmed by the completely opposite green fluorescence of Probe 1 and red fluorescence of Probe 2 observed by fluorescence spectra and naked eyes. The probes take advantages of the large Stokes shift (~160 nm), rapid response (30 s), anti-interference performance and low detection limit (Probe 1 : 12.4 nM, Probe 2 : 101 nM). The sensing mechanism is certificated to the nucleophilic attack of CN− to electron-deficient cyanoethylene group of probes, which was demonstrated by 1H NMR titration, HR-MS, Job's plot and IR spectroscopy. Density functional theory (DFT) calculations were carried out to analyze the mechanism in theory. Further, practical applications were studied. Easy-to-use test strips treated with Probe 1 or Probe 2 are capable of CN− detection in pure drinking water. The good biocompatibility and membrane penetrability have achieved the bioimaging capability of Probe 1 and Probe 2 in living HepG-2 cells, making the probes promising for use in real lives. [Display omitted] • Probes show high selectivity towards cyanide (CN−) and good anti-interference ability against other competing anions. • Probes show high reactivity in aqueous media, making them can be used in actual environment and biological system. • Probes are capable of CN− detection by easy-to-use test in pure drinking water. • Probes have large Stokes shifts and low cytotoxicity so that they can be utilized as CN− sensors in living cells. [ABSTRACT FROM AUTHOR]

Scutellaria baicalensis is one of the widely used Chinese traditional medicines, and wogonin is one of major active components in it. However, the mechanism of action of wogonin has largely remained unclear. In this work, we designed a fluorescent probe, namely ATTO565-WGN, by conjugating wogonin with the fluorophore ATTO565 based on Mannich reaction via a flexible chain linker. In vitro assays verified that the ATTO565-WGN conjugate has a similar anti-proliferative activity to wogonin against human A549 and HeLa cancer cell lines. Combining co-localization and competition studies, confocal fluorescence imaging clearly demonstrated that the fluorescent wogonin probe predominantly located in mitochondrial area of living cells, indicating that wogonin acts at mitochondrion to exert its pharmacological functions. Significantly, the conjugated ATTO565 fluorophore conferred the wogonin probe STED (Stimulated Emission Depletion) feature, enabling STED fluorescence living cell imaging with a 55 nm of ultrahigh spatial resolution. This will greatly beneficial for the in situ investigation of interactions between wogonin and biological targets at the finely organized and dynamic mitochondria of living cells. Moreover, this work also provides novel insights into rational design of mitochondrion targeting fluorescence probes for ultrahigh resolution living cell imaging. [Display omitted] • A fluorescent probe of wogonin was synthesized and applied for living cell imaging. • ATTO565 conferred the probe STED feature without altering bioactivity of wogonin. • CLSM imaging unraveled that wogonin predominantly targets mitochondrion. • STED feature enabled localization of wogonin under ultrahigh spatial resolution. [ABSTRACT FROM AUTHOR]

Long and real time imaging of cell membrane is very important for better understanding of cell performances in physiological and pathological processes. Nowadays, fluorescence probe analysis has become an indispensable tool for monitoring cell membrane. Herein, a novel fluorescent probe based on specific recognition of GABA A receptor was developed for imaging cell membrane. The probe synthesized in this work has been successfully applied to image different kinds of cell membrane with some advantages over the reported probes. Moreover, the probe also showed good superiority in the preliminary screening GABA A drugs. Image 1 • A novel fluorescent probe based on GABA A receptor was developed for imaging membrane. • The probe was successfully applied to image many kinds of cell membrane. • The probe shows many advantages over reported probes designed for imaging membrane. • The probe was attempted preliminarily to use as a tool for screening GABA A drugs. [ABSTRACT FROM AUTHOR]

Intracellular pH is a key physiological factor for controlling the activities and functions of cells and lysosome is a vital subcellular organelle. Thus, developing a novel lysosome-targeting fluorescence probe for selective and sensitive detection of lysosomal pH in living cells is very important. In this work, we synthesized a series of fluorescence probes based on imidazole-fused benzothiadiazole. The optical properties of these probes were easily adjusted by modifying the substituents with different electron-withdrawing/donating ability in imidazole moiety. All of them showed acid-response and decreased fluorescence intensity during pH values changing from 4.0 to 8.5. The introduction of morpholine group allowed them to specifically respond to the changes of lysosomal pH. Among them, probe MIBTAA possessed a suitable p K a value (5.3) and showed good linear response to pH (R2 = 0.9918) with red emission when pH changed from 4.4 to 5.6. The probe was successfully applied for monitoring pH variation in living cells induced by proton-pump inhibitor Baf-A1 and chloroquine, indicating its great potential for pH imaging in biological applications. A series of fluorescence probes based on imidazole-fused benzothiadiazole scaffold were developed for pH sensing. Image 1 • A series of fluorescence probes were designed and synthesized for pH measurement. • The probes were based on imidazole-fused benzothiadiazole molecular skeleton. • The optical properties of fluorescence probes were regulated by different electron-withdrawing/donating substituents. • The lysosomal pH changes were successfully monitored by probe MIBTAA. [ABSTRACT FROM AUTHOR]

Developing a specific and sensitive method for endogenous hydrazine detection in living systems is valuable to understand its various pathological events. In this work, two novel fluorescent chemosensors (C1, C3) based on triphenylamine Schiff-base derivative and reference dyes (C2, C4) were prepared in relatively high yield (more than 72% yield). The aggregation induced emission (AIE) properties of sensors were investigated through UV–Visible, dynamic light scattering, X-ray diffraction, fluorescence spectrophotometric analyses as well as scanning electron microscope images (SEM). The results indicated that probes C1 and C3 exhibited strong AIE property in DMF/H 2 O (1:1, v/v) mixture system with brilliant yellow fluorescence emission (560 nm) observed under 365 nm UV lamp. The experiments of sensing indicated that probes C1 and C3 possessed the sequentially detecting abilities for hydrazine with high sensitivity, specificity as well as an extremely low detection limit (55.1 nM), which was due to blocking of AIE process of probes C1 and C3 by special chemical reaction (-CH N- moiety transformed into –CH 2 -NH- group) after hydrazine addition, resulting in the increase in water solubility and a weak emission in aqueous media. Furthermore, 1H NMR, SEM and fluorescence titration experiment was also conducted to confirm the sensing mechanism. For biological application, probes C1 and C3 presented a good bio-imaging performance and showed the similar fluorescence quenching after adding hydrazine. Therefore, the probes are suitable for the fluorescence imaging of exogenous hydrazine in HeLa cells. Image 1 • Synthesis of conjugated chromophores carrying ESIPT segments. • A novel 'turn-on' probes for hydrazine based on ESIPT segments with AIE properties have been successfully obtained. • Detection abilities for hydrazine with high sensitivity, specifity and lower limit of detection (LOD). • The sensitivity of probe is demonstrated successfully for selective imaging of hydrazine in living cells. [ABSTRACT FROM AUTHOR]