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• Development of a novel red-emitting fluorescent probe (HSA) for the detection of Cys. • The probe can high sensitivity detect Cys with a low LOD. • Successfully verified the experimental results by the theoretical calculation study. • The probe can be used for exogenous Cys monitoring and endogenous Cys cell imaging experiments. Herein, we synthesized a red-emitting fluorescence turn-on probe (HSA) for specific detection of cysteine (Cys) over other biothiols (glutathione (GSH) and homocysteine (Hcy)). The acrylate group was chosen as the recognition site for specific discrimination of Cys. Absorption and emission spectra display a high selectivity towards Cys over GSH/Hcy, organic small-molecule interfering substances and anions, with a high sensitivity towards Cys (0.12 μM) in 1% ethanol-containing PBS buffer solution (25 mM, pH = 7.4). Density functional theory (DFT) and time-dependent DFT (TDDFT) calculations were conducted to clarify the luminescence mechanism of the probe. Furthermore, the probe was successfully applied to the determination of free Cys in human serum and the fluorescence imaging of endogenous Cys in living cells. [ABSTRACT FROM AUTHOR]

Singlet oxygen plays an important role in cancer chemotherapy and biology of reactive oxygen species. In recent years, there are some reports of selective fluorescent probes for detection and imaging of singlet oxygen but the existing probes have some major drawbacks including complicated synthetic routes, poor fluorescence enhancement effects. We report herein that anthracenylmethyl modified non-fluorescent derivatives of fluorescein and rhodamine-6G can reacts with 1 O 2 , which resulted in C C bond cleavage that detach anthracene unit from the fluorophores resulting in strong fluorescence enhancement. These probes exhibit high selectivity and sensitivity in detection and imaging of 1 O 2 in chemical and in living cells. Our approach makes it simple and flexible for development of reaction-based 1 O 2 fluorescent probes for broad application in chemical, biomedical, and environmental sciences. [ABSTRACT FROM AUTHOR]

A novel dual site controlled probe has been developed on the basis of rhodamine and biphenylcarbonitrile unit. The probe showed not only rapid fluorescence response to pH, but also good colorimetric recognition performance for copper ions in the HEPES buffer solution (pH 7.0). The optimal geometric configuration of the probe RhB-H with different structures and the [RhB-H-Cu 2+ ] complex were calculated at B3LYP level by DFT method. On this basis, the response mechanism of pH was analysed combining with the 1 H NMR titration experiment. Moreover, the cytotoxicity studies indicated that the probe had good biocompatibility and low toxicity. Then the probe was also successfully applied on real-time monitoring of the intracellular pH changes by exhibiting different fluorescence and emission intensity. These results demonstrated that the probe could be usefully involved in biological and biomedical research. [ABSTRACT FROM AUTHOR]

Lipid droplets (LDs) are critical cellular organelles associated with various physiological processes in eukaryotic cells. To visualize LDs and research their complex physiological functions, various fluorescence imaging models including the confocal imaging, the lambda scan imaging and the stimulated emission depletion (STED) super-resolution imaging have been successfully employed in recent years. However, since different fluorescence imaging models have different requirements for fluorescent probes, it is very challenging to employ single fluorescent probe for multimodal fluorescence imaging. Herein, an advanced organic fluorescent probe Lipi-DSBOMe has been sophisticatedly developed for purpose. Featuring with the advantages of high staining selectivity towards LDs, polarity sensitive luminescence, high photostability and low STED saturation intensity, this fluorescent probe is well suited for multimodal fluorescence imaging. For instance, employed with this probe for three-dimensional (3D) confocal imaging to quantitatively determine the change of number of LDs under the oleic acid stimulation, lambda scan imaging to precisely measure the polarity of LDs in different types of cells, and STED imaging to measure the size of LDs with the state-of-the-art resolution (42 nm). In overall, employing this single fluorescent probe for multimodal fluorescence imaging has allowed to provide abundant information about LDs, thus effectively promoting the LDs biology studies. [Display omitted] • An advanced fluorescent probe was developed for multimodal imaging of LD. • Abundant information about LD could be provided by multimodal fluorescence imaging. • The highest resolution (42 nm) of LD was achieved in STED super-resolution imaging. [ABSTRACT FROM AUTHOR]

An imidazo[1,5-α]pyridine-based fluorescence probe NIPY-DNP with a large Stokes shift (193 nm) has been successfully developed for highly selective, sensitive and rapid detection of H 2 S. The selective deprotection of 2,4-dinitrophenyl ether group of NIPY-DNP by H 2 S led to a dramatic fluorescent enhancement (273-fold) at 505 nm within 5 min in PBS buffer solution. The sensing mechanism is proposed on the basis of the thiolysis reaction by H 2 S, which has been confirmed by HPLC and HRMS. The detection limit is 0.36 μM, which is superior to the other reported H 2 S probes. Additionally, cell imaging studies demonstrated that NIPY-DNP could be used to visualize H 2 S in living cells. [ABSTRACT FROM AUTHOR]

An efficient and highly selective dihydrazone based fluorescent probe N ′, N ′–bis((2–hydroxynaphthalen–1–yl)methylene)malonohydrazide (H 2 nmh), has been synthesized for selective detection of Al 3+ ions and characterized by different physico–chemical and spectroscopic techniques. The probe shows an enhanced fluorescence in the presence of Al 3+ ions in ethanol–water (2:3 v/v) solution which is not observed in the presence of other cations (Na + , K + , Mg 2+ , Ca 2+ , Mn 2+ , Fe 3+ , Co 2+ , Ni 2+ , Cu 2+ , Zn 2+ , Pb 2+ , Cd 2+ and Hg 2+ ). The binding modes of H 2 nmh with Al 3+ were studied by UV–vis, fluorescence and 1 H NMR titrations. The probe act as dibasic hexa–dentate ligand and interacts with two Al 3+ ions with a binding constant K B = 5.74 × 10 9 M −1 and detection limit 5.78 × 10 −8 M. Detailed insights of probe–metal interaction mechanism were studied by mean of density functional theory (DFT) as well as time dependent–DFT calculation. MTT assay on live MCF–7 cells has been performed to evaluate the cytotoxicity of the probe which suggests viability of the probe to MCF–7 cells even at higher concentration (100 μM) with no serious cytotoxicity in cells. Live cell imaging study clearly indicates that the accumulation of Al 3+ in the cytoplasm of cells can be detected by H 2 nmh. [ABSTRACT FROM AUTHOR]

Herein, a simple and green method was developed for the construction of water soluble fluorescent gold nanoclusters (Au NCs) with the assistance of l -carnosine as both a protecting ligand and a weak reducing agent. The as-prepared Au NCs, with the smaller size (2.31 nm) and longer fluorescence lifetime (7.48 ns), exhibited bright blue photoluminescence under UV light (365 nm) with a quantum yield of 3.4%, excellent stability, and low toxicity for cancer HeLa cell imaging. [ABSTRACT FROM AUTHOR]

A red-emitting (above 600 nm) fluorescent probe based on 3-hydroxyflavone has been developed for the detection of hydrogen sulfide with high sensitivity, good selectivity and a large Stokes shift (162 nm). When the probe was treated with hydrogen sulfide, a remarkable fluorescence enhancement (112-fold) was obtained. Application of this probe was successfully demonstrated by imaging intracellular hydrogen sulfide in living RAW264.7 cells. [ABSTRACT FROM AUTHOR]

• A novel fluorescent probe was synthesized for the detection of ONOO− by conjugating dicyano-vinyl with benzopyran-chromone. • The probe shows specifically selectivity over other biologically relevant ROS/RNS/RSS. • The sensing mechanism is the cleavage of the carbon-carbon double bond by the nucleophilicity and oxidation of peroxynitrite. • The probe has a certain mitochondrial targeting and localization effect. • BC-PN-2 can accurately identify ONOO− in mitochondria by imaging of exogenous ONOO− in HepG2 cells. A novel fluorescent probe (BC-PN-2) for the detection of ONOO− was synthesized by conjugating dicyano-vinyl with benzopyran-chromone. The dicyano-vinyl group can be destructed by ONOO− to generate an aldehyde group resulting in strong fluorescence. Compared with the general fluorescence probes, a novel reactive site to detect ONOO− in mitochondria is used in this probe and the results show short response time, high sensitivity and excellent selectivity toward ONOO− among reactive oxygen species (ROS) and reactive nitrogen species (RNS) in PBS. Subsequent fluorescence imaging shows the high membrane permeability, a certain mitochondrial targeting and localization effect of the probe. In addition, the product BC-aldehyde cannot permeate through the membrane. Meanwhile, BC-PN-2 can accurately identify ONOO− in mitochondria by imaging of exogenous ONOO− in HepG2 cells and prove detected ONOO− are from mitochondria. [ABSTRACT FROM AUTHOR]

• We have developed a sensor that detects N 2 H 4 in 99 % water environment referening drug molecular design methods. • A reasonable strategy for the construction of water-soluble fluorescent sensors was developed. • The measurement scope of this sensor is 0.28∼120μM, LOD = 1.22ppb. • Long stokes shift (91nm) can effectively eliminate the inherent bioluminescence interference in short wavelengths. Hydrazine is a serious hazard for humans; therefore, the detection of N 2 H 4 is extremely important. In recent years, fluorescence sensing, which is a simple and efficient method, has attracted immense attention. Although sensors for hydrazine have been reported, only a few have successfully worked in almost pure water media, Therefore, organic cosolvents are required, however, they are known to interfere with the analysis of the real sample. Furthermore, a few currently known hydrazine sensors have emission wavelengths smaller than the size of the organism itself, thereby making it difficult to eliminate the inherent bioluminescence interference at short wavelengths. In order to solve these problems, we have developed a new type of water-soluble(LogP (Oct/buff) = 1.68, LogD7.4=-1.97), fluorescent, colorimetric sensor. This sensor is based on the ICT mechanism to specifically detect N 2 H 4 in colorimetric and proportional modes (measurement scope is 0.28–120 μM, LOD = 1.22 ppb). In addition, it was successfully used to image A549 cells and detect hydrazine in river water samples and water vapor. [ABSTRACT FROM AUTHOR]