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A novel highly selective chemosensor Z based on rhodamine B hydrazone derivatives was designed and synthesized, and it showed both colorimetric and “turn-on” fluorescence responses for CN− in an aqueous solution. The results showed that after adding CN− ions in aqueous solution, the chemosensor Z showed significant color change from colorless to pale-yellow, which was visible to the naked eye, and it rapidly produced strong green fluorescence. The probe could distinguish CN− by deprotonation and intramolecular charge transfer (ICT) mechanisms, as evidenced by 1H-NMR titration and DFT calculations. In addition, the detection limit of the fluorescence response of the sensor for CN− was 5.81 × 10−8 M, which was measured by titration. The chemosensor Z has been successfully used to detect CN− in sprouting potatoes. Z-containing test strips have also been prepared, and they can be used as a colorimetric tool for CN− detection in potential applications. [ABSTRACT FROM AUTHOR]

A chlorinated coumarin-aldehyde was developed as a colorimetric and ratiometric fluorescent probe for distinguishing glutathione (GSH), cystenine (Cys) and homocysteine (Hcy). The GSH-induced substitution-cyclization and Cys/Hcy-induced substitution-rearrangement cascades lead to the corresponding thiol-coumarin-iminium cation and amino-coumarin-aldehyde with distinct photophysical properties. The probe can be used to simultaneously detect GSH and Cys/Hcy by visual determination based on distinct different colors – red and pale-yellow in PBS buffer solution by two reaction sites. From the linear relationship of fluorescence intensity and biothiols concentrations, it was determined that the limits of detection for GSH, Hcy and Cys are 0.08, 0.09 and 0.18 μM, respectively. Furthermore, the probe was successfully used in living cell imaging with low cell toxicity. [ABSTRACT FROM AUTHOR]

The fluorescent probe is constructed by incorporating an α, β-unsaturated pyridinium to a pyrene fluorophore. The chemodosimeter has shown a selective and sensitive response to sulfite anion over other various anions and biological thiol through a Michael addition of the sulfite to the alkene of the probe. Meanwhile, it can be easily observed that the color of the probe for sulfite changes from yellow to colorless by the naked eye, and from yellow to blue under UV lamp immediately after the sulfite is added. [ABSTRACT FROM AUTHOR]

In this paper, we report a highly selective and sensitive ratiometric NIR fluorescent probe that can be used for real-time detection of the biologically important hypochlorite with colorimetric and significant NIR fluorescent turn-on signal changes at NIR excitation wavelength. In addition, experiments showed that this probe can be applied to detect hypochlorite in tap water, serum samples, and living cells with low cytotoxicity. [ABSTRACT FROM AUTHOR]

An ultrasensitive method for the detection of protein is critically important in fundamental research and practical applications due to the low abundance of disease markers in body fluids or tissues. To detect the trace levels of disease markers with high sensitivity and specificity, a sensitive colorimetric biosensor for protein assay was developed using gold nanoparticles (AuNPs) and rolling circle amplification (RCA). After binding the biotinylated primer/circular template to the streptavidin-conjugated sandwich ELISA immunocomplex, the biotinylated primer was isothermally extended to generate single-stranded DNA (ssDNA). Sequentially, the padlock DNA was added and hybridized with the RCA products. The aggregation of the additional AuNPs in the supernatant containing the surplus padlock DNA and a certain concentration of salt could then be observed. The established sensor allowed for the specific detection of α-fetoprotein (AFP) with a detection limit of 33.45 pg mL−1. It was also demonstrated that this method could distinguish 500 pg mL−1 AFP with the naked eye. In addition, this biosensor could be applied to complex sample analysis and could be further used as a universal method for any protein or virus determination by changing the corresponding antibodies. [ABSTRACT FROM AUTHOR]

A new ‘‘naked-eye’’ ratiometric colorimetric and fluorometric chemodosimeter (PBF) was constructed to enable trace vapor detection of hydrazine. This probe utilizes an irreversible and fast hydrazine-promoted cleavage of the ester linkage in PBF. This probe was shown to be highly selective for hydrazine, and showed real time response as well as a positive linear relationship to hydrazine concentration. The probe also shows an excellent performance in the ‘‘dip stick’’ method. [ABSTRACT FROM AUTHOR]