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Abstract: New rhodamine derivatives bearing binaphthyl group were synthesized as selective fluorescent and colorimetric sensors for Cu2+. Highly selective “off–on” type fluorescent changes were observed upon the addition of Cu2+. Selective fluorescent enhancement of two rhodamine derivatives was attributed to ring opening from the spirolactam (nonfluorescent) to ring-opened amide (fluorescent). A chemo-sensing based on rhodamine derivative was further applied to the microfluidic system. [Copyright &y& Elsevier]

• The first fluorescent sensor for ratiometric detection of carprofen was reported. • This sensor exhibited the rapid response, high sensitivity and high selectivity. • The limit of detection for carprofen was 0.196 mg/kg. • The sensing mechanism was studied using mass spectra and molecular docking. • This sensor successfully achieved monitoring of carprofen in real food samples. Carprofen (CPF) is a non-steroidal anti-inflammatory drug that has been widely used in livestock for the treatment of fever and inflammation. Yet the massive use of CPF comes at the cost of its residue ubiquitous in the environment thus leading to a huge risk to human health. Therefore, development of a convenient analytical method for monitoring CPF is of considerable importance. In this study, a dual-emissive supramolecular sensor was facilely constructed using bovine serum albumin as the host and an environmentally sensitive dye as the guest. This sensor, for the first time, successfully realized the fluorescent detection of CPF with a rapid response, high sensitivity and selectivity. More importantly, this sensor exhibited a very unique ratiometric response to CPF, which endowed this method with satisfactory detection accuracy for food analysis. To the best of our knowledge, this is the first fluorescent method for fast determination of CPF in food. [ABSTRACT FROM AUTHOR]

This paper describes the design and synthesis of a benzothiazole-based fluorescent probe ( H 1 ) for zinc and cadmium ion detection and discrimination, using cysteine as an auxiliary reagent. Among the various metal ions tested, zinc and cadmium ions induced blue-shifted emissions of probe H 1 from 573 nm to 520 nm and 540 nm, respectively. The addition of cysteine caused the emission of H 1 -Cd 2+ to red-shift back to 573 nm. In contrast, the emission of H 1 -Zn 2+ with the addition of cysteine only decreased without any red-shift of wavelength. Furthermore, confocal laser scanning micrographs of HeLa cells demonstrated satisfactory cell permeability of H 1 and selectivity toward zinc and cadmium ions in living cells. Test strip experiments suggest that probe H 1 can recognise zinc and cadmium ions together by a remarkable fluorescence change, thus providing a convenient method for tracking zinc and cadmium ions in biological systems. [ABSTRACT FROM AUTHOR]

In this paper, a new rhodamine derivative bearing thiazole and thiocarbonyl moieties 1 was synthesized and its sensing behaviors toward various metal ions were investigated by fluorescence spectroscopies and UV/Vis. The ring-opening process of spirolactam enables the selective fluorescence enhancement and colorimetric change for Hg 2+ in CH 3 CN-HEPES buffer (0.01 M, pH 7.4) (3:7, v/v). The selectivity and sensitivity of 1 towards Hg 2+ lead to sensor 1 applied to microfluidic device and even used to functions Hg 2+ sensing in Hela cells. [ABSTRACT FROM AUTHOR]

In the current study, we report the first example of polydiacetylenes (PDAs), where our PDA-based system acts as both a sensing probe and killer for bacteria. The contact of imidazolium and imidazole-derived PDA with various bacterial strains including MRSA (methicillin-resistant Staphylococcus aureus ) and ESBL-EC (extended-spectrum β-lactamase-producing Escherichia coli ) results in a distinct blue-to-red colorimetric change of the solution as well as a rapid disruption of the bacterial membrane, which is demonstrated by transmission electron microscopy and confocal microscopy. Zeta potential analysis supports that antibacterial activity of the PDA solution originates from an electrostatic interaction between the negatively charged bacterial cell surface and the positively charged polymers. These results suggest that the PDA has a great potential to carry out the dual roles of a probe and killer for bacteria. [ABSTRACT FROM AUTHOR]

Polydiacetylenes (PDAs), as smart materials with very unique properties, are widely used for sensing various analytes. Derived from the monomers 1-(1,4,7,10,13-pentaoxa-16-aza-cyclooctadec-16-yl)-pentacosa-10,12-diynamide (PCDA-L) and 10,12-pentacosadiynoic acid (PCDA), we report a conjugated polymer (poly-PDA-L) for lead ions detection. The PDA sensing system showed rapid fluorescent and colorimetric response and high sensitivity to Pb 2+ in 100% aqueous solution, as well as the color change was obvious to the naked eye. Excellent fluorescence response change and a good linear relationship between fluorescent PDA intensity and Pb 2+ amount were observed based on fluorescence microscope images, with a detection limit of 1 μM. The fluorescent and colorimetric responses were attributed to the binding between the moiety 1-aza-18-crown-6-ether of poly-PDA-L and Pb 2+ . This interaction further disturbs the backbone of the PDA polymer, allowing the release of the strain energy imposed on the alkyl side chains generated during polymerization, leading to the observed change in optical properties. [ABSTRACT FROM AUTHOR]

Abstract: A new fluorescent probe based on fluorescein fluorophore displays an excellent selectivity and sensitivity for GSH in buffer solution containing CTAB. The fluorescence intensity of sensor is linearly proportional to GSH concentrations ranging from 0 to 10μM, and as low as 22nM concentration of GSH was evaluated with 3.3 σ/s. The optical changes are attributed to the release of free fluorescein after the electron withdrawing dinitrophenyl ether reacted efficiently with GSH in CTAB micelles. The enhanced selectivity toward GSH over Cys and Hcy considered to be related to the carboxyl groups in thiols. The confocal microscopy experiments implied that this probe is a promising candidate for imaging of GSH in living cells. [Copyright &y& Elsevier]

Abstract: A quinoline-based fluorescent chemosensor was reported for the simultaneous detection of Zn2+ and Cd2+ in aqueous solution. In HEPES buffer, among various metal ions, only Zn2+ and Cd2+ exhibited fluorescence enhancement at 497nm accompanied by the red-shift emission wavelength. The mechanism was proposed that internal charge transfer effect induced by binding with Zn2+ or Cd2+ produced the fluorescence changes. With the addition of cysteine, the fluorescent solution containing sensor and Cd2+ show the decreased fluorescence at 497nm and the increased fluorescence at 420nm, which was attributed to the dissociation of the complex formed by sensor and Cd2+. In contrast, the fluorescence of solution containing sensor and Zn2+ is unchanged with the addition of Cys. Furthermore, the confocal microscopy experiments indicated that this sensor can provide real-time detection for intracellular Zn2+ and Cd2+. [Copyright &y& Elsevier]

Abstract: Hydrogen sulfide (H2S) is an important gaseous mediator in cellular physiology and pathology. For understanding the biological action of H2S to both healthy and disease states, it is important to develop H2S-selective sensor. Herein we report a colorimetric and fluorescent probe, which employs an NBD moiety as fluorophore, and is equipped with azide group as H2S-active unit. The probe exhibits selective and sensitive response to H2S in aqueous solution. By employing 1 μM sensor, the detection limit was evaluated to be 680 nM with a signal-to-noise ratio of 3. Confocal microscopy imaging experiments demonstrate the probe has potential as a powerful tool for the imaging of hydrogen sulfide in living cells. [Copyright &y& Elsevier]

Abstract: A fluorescein-based sensor bearing nitroolefin moiety for the detection of thiols was prepared. Upon addition of thiols, such as cysteine (Cys), homocysteine (Hcy) and glutathione, the solution containing sensor showed an increase of absorption intensity at 497 nm with a slight blue-shift as well as the enhancement in fluorescence intensity at 520 nm. The fluorescence enhancement and absorption change are attributed to the Michael addition of thiols to the double bond of nitroolefin moiety in sensor. The probe displays a fast response to Cys with the rate constant (k obs) of 2.3 min−1 and the detection limit to Cys was evaluated to be 0.2 μM. The confocal microscopy experiments demonstrate that this sensor is potential for the imaging of thiols in living cells. [Copyright &y& Elsevier]

The nicotinamide adenine dinucleotide derivatives (NADPH, NADP+, NADH, and NAD+) are important redox cofactors that involve in many biological activities, and their concentration levels are associated with a variety of diseases. In this work, an imidazolium functionalized polydiacetylenes sensing system (IM-PDAs) is reported to selectively detect the reduced form of nicotinamide adenine dinucleotide phosphate (NADPH). Depending on the electrostatic attraction between the positively charged imidazolium heads and the negatively charged phosphate groups, the sensing system exhibits colorimetric and fluorescent responses when exposed to NADPH and its oxidized form (NADP+); while the system does not respond to the less negatively charged NADH and NAD+ at the concentration range tested in this study. Owing to the positively charged nicotinamide of NADP+, the detection sensitivity of IM-PDAs towards NADP+ is much lower than that towards NADPH, successfully differentiating NADPH from the rest three cofactors. Furthermore, IM-PDAs loaded paper-based sensor is constructed and demonstrates the potentials of IM-PDAs based sensing device for practical applications in NADPH detection. Image 1 • A polydiacetylenes-based sensing system was constructed for selective detection of NADPH. • The sensing system owns an ultralow detection limit of 23.5 nM towards NADPH. • The paper-based PDAs sensing device also demonstrated the ability of selectively detecting NADPH. [ABSTRACT FROM AUTHOR]