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A series of novel near-infrared (NIR) xanthene-chalcone fluorophores were constructed through a modular synthesis with the electron-donating xanthene moiety and the electron-withdrawing chalcone moiety. These fluorophores are convenient for fluorescence imaging in living cells, benefiting from their NIR emissions (650–710 nm), large Stokes shifts (>100 nm), moderate quantum yields and low cytotoxicity. The substituted hydroxyl group of the xanthene-chalcone fluorophore HCA-E facilitates the development of multifunctional fluorescent probes. As an example, a highly sensitive and selective probe N-HCA-E for glutathione (GSH) detection was developed based on the fluorophore HCA-E. A 4-nitrobenzenesulfonyl (4-Ns) group was introduced to cage the hydroxyl group of HCA-E, which was used as a selective recognition site for the thiol of GSH and an effective fluorescence quencher. Probe N-HCA-E revealed NIR "turn-on" fluorescence (709 nm) for endogenous and exogenous GSH detection in lysosomes with a large Stokes shift (129 nm) and high anti-interference ability. [ABSTRACT FROM AUTHOR]

Hydrazine has been identified as an environmental contaminant and a probable human carcinogen for its high toxicity. Thus, the development of detection methods for mapping hydrazine in solution and biosystems, particularly in vivo , is of great significance. Here, through firstly exploited 2-thiophenecarbonyl moiety as a recognition unit for hydrazine, a novel near-infrared (NIR) fluorescent probe CyOS is obtained based on hemicyanine. The probe shows high selectivity towards hydrazine over various amino acids and common ions with a significant fluorescence enhancement at 701 nm in the presence of hydrazine. Further, it has a sufficiently low detection limit (0.78 ppb). And most importantly, due to its good cell membrane permeability and low cytotoxicity, CyOS has been applied to monitor and image hydrazine in living cells, tissues and mice. To the best of our knowledge, it is the first time to visualize hydrazine in deep living tissues (∼90 μm). [ABSTRACT FROM AUTHOR]

Two functionalized rhodamine based probes have been rational designed and synthesized. The probes have sufficiently high selectivity and sensitivity for the detection of Fe 3+ ion both by fluorescence and ultraviolet spectroscopy with strong ability of anti-interference performance. The detection process has been shown to be reversible and involves the fluoran ring-opening upon complexation with Fe 3+ . The obvious fluorescence image obtained from confocal laser scanning microscopy of the detection of Fe 3+ in living L929 cells demonstrate that the probes could contribute to significant breakthroughs in understanding the critically important functions of Fe 3+ in related cells and biological organs. [ABSTRACT FROM AUTHOR]

A dual-emission ratiometric fluorescence sensor (CDs@CdTe@MIP) with a self-calibration function was successfully constructed for AMO detection. In the CDs@CdTe@MIP system, non-imprinted polymer-coated CDs and molecule-imprinted polymer-coated CdTe quantum dots were used as the reference signal and response elements, respectively. The added AMO quenched the fluorescence of the CdTe quantum dots, whereas the fluorescence intensity of the CDs remained almost unchanged. The AMO concentration was monitored using the fluorescence intensity ratio (log(I647/I465)0/(I647/I465)) to reduce interference from the testing environment. The sensor with a low detection limit of 0.15 μg/L enabled detection of the AMO concentration within 6 min. The ratiometric fluorescence sensor was used to detect AMO in spiked pork samples; it exhibited a high recovery efficiency and relative standard deviation (RSD) of 97.94–103.70% and 3.77–4.37%, respectively. The proposed highly sensitive and selective platform opens avenues for sensitive, reliable, and rapid determination of pharmaceuticals in the environment and food safety monitoring using ratiometric sensors. [ABSTRACT FROM AUTHOR]

A novel rhodamine based 2-guanidinobenzimidazole functionalized probe RhoG was rationally designed and synthesized for the detection of tetravalent tin in environmental, geological, and biological samples with excellent selectivity, sensitivity, photostability and anti-interference performance. The mechanism investigation confirmed that guanidinobenzimidazole provided binding sites for Sn 4+ and facilitate the formation of the complex. Successfully fluorescent imaging experiments in living L929 cells and MG-63 cells by confocal laser scanning microscopy presented a promising candidate for tracking tetravalent tin in biological organisms and processes thus contribute to significant breakthroughs in understanding the critically important functions of tetravalent tin. [ABSTRACT FROM AUTHOR]

Tetracyclines (TCs) residues in animal-based foods may cause consumer poisoning or allergic reactions, as well as resistance of pathogenic microorganisms. Therefore, a method to accurately monitor TCs is urgently needed. Here, a sensitive and greenificated molecularly imprinted fluorescent sensor (CDs@MIP) for detecting TCs residues using non-covalent imprinting binding method has been synthesized in a simple and safe manner. The sensor was demonstrated to contain specific adsorption sites and high adsorption capacity by static adsorption test results and Freundlich and Langmuir model analyses, and the maximum adsorption capacity was 45.8 mg/g. Moreover, the sensor exhibited intense blue-green fluorescence under UV light, and the fluorescence was gradually quenched as TCs was adsorbed to achieve the detection. The fluorescent spectrum experiment demonstrated that the prepared sensor has good recognition and detection performance for TCs with a linear range of 0.02–50 mg/L and a detection limit of 0.18 μg/L. Furthermore, This sensor is recyclable and can be used to determine TCs content in pork with a recovery rate of 98 %–108 %. Therefore, the constructed sensor provides a new convenient strategy for detecting TCs residues. [Display omitted] • A sensor (CDs@MIP) that specifically recognizes TCs was constructed. • Preparation and use of CDs@MIP comply with GREENIFICATION requirements. • CDs@MIP has good reusability, wide linear range, and low detection limit. • CDs@MIP has good anti-interference ability and can detect TCs residues in pork. [ABSTRACT FROM AUTHOR]

Three congeneric fluorescent sensors that utilize Rhodamine B were developed for the detection of mercury (II) ions. This series of sensors are functionalized by various differently substituted cinnamyl aldehyde, with C N Schiff base and C S structural motif as their core segment. The performance of these sensors adjusted by steric hindrance were investigated by absorption and fluorescence spectrum, and illuminated, summarized and confirmed using DFT calculations by frontier orbital theory and Fukui- function. In addition, living cell and living mice imaging demonstrated that all the sensors could serve as a potential fluorescent agent for quantitative mercury (II) ion imaging in living organism. The obvious morphology change reveal that the coordination of HgCl 2 upon these sensors may have a great influence on the material performance to a certain extent. This approach provides a significant strategy for studying structure-property relationships and guiding the synthesis of sensors with various optical properties. [ABSTRACT FROM AUTHOR]