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[Display omitted] • A responsive probe EHDI for ratiometric fluorescence analysis of bisulfite (HSO 3 -) and sulfite (SO 3 2-) is developed. • The probe EHDI exhibits blue shifts in both the UV–Vis and emission spectra upon responding to HSO 3 -. • The probe EHDI features high sensitivity and selectivity for HSO 3 - detection in buffer and imaging in live cells. • Detection of HSO 3 - in beef samples by probe EHDI is validated by HPLC. The development of reliable probe technology for the detection of bisulfite (HSO 3 -) in situ in food and biological samples is contributing significantly to food quality and safety assurance as well as community health. In this work, a responsive probe, EHDI, is developed for ratiometric fluorescence detection of HSO 3 - in aqueous solution, meat samples, and living cells. The probe is designed based on the HSO 3 - triggered 1,4-addition of electron deficit C = C bond of EHDI. As a result of this specific 1,4-addition, the π-conjugation system was destructed, resulting in blue shifts of the emission from 687 to 440 nm and absorption from 577 to 355 nm. The probe has good water solubility, high sensitivity and selectivity, allowing it to be used for imaging of HSO 3 - internalization and production endogenously. The capability of probe EHDI for HSO 3 - was then validated by traditional HPLC technology, enabling accurately detect HSO 3 - in beef samples. The successful development of this probe thus offers a new tool for investigating HSO 3 - in situ in food and biological conditions. [ABSTRACT FROM AUTHOR]

Naphthyridine-based fluorescent probe H1 was synthesized and characterized for the quantification and selective detection of Uric Acid ( UA ) in live cell. In presence of UA , H1 forms the specific host-guest complex mainly through intermolecular hydrogen bonding and aromatic stacking which produces “turn-off” fluorescence. The probe and UA is found to be 1:1 stoichiometry on the basis of absorption and fluorescence titrations. The probe H1 has been shown to detect UA up to 0.6 µM at pH 7.4. DFT-TDDFT calculations were performed in order to demonstrate the sensing mechanism and the electronic properties of the receptor-donor complex. The selectivity was evaluated in Vero cells in the presence of UA with other purine derivatives, structurally similar to UA . It was found to exhibit no cytotoxicity effect in tested concentration of H1 and good membrane permeability for the detection of UA in living cell system. The unknown concentration of UA in serum and urine can be measured easily using the fluorescence property of probe H1 . [ABSTRACT FROM AUTHOR]

Viruses represent an important class of pathogens that have had an enormous impact on the health of the human race. They are extraordinarily diverse; viral particles can range in size from ∼80 nm to ∼10 μm in length, and contain genomes with RNA or DNA strands. Regardless of their genome type, RNA species are frequently generated as a part of their replication process, and for viruses with RNA genomes, their loading into the virion represents a critical step in the creation of infectious particles. RNA imaging tools represent a powerful approach to gain insight into fundamental viral processes, including virus entry, replication, and virion assembly. Imaging viral processes in live cells is critical due to both the heterogeneity of these processes on a per cell basis, and the inherent dynamics of these processes. There are a number of methods for labeling RNA in live cells; we’ll introduce the myriad of methods and then focus on one approach for labeling viral RNA, using multiply-labeled tetravalent RNA imaging probes (MTRIPs), which do not require engineering of the target RNAs. We feel this approach is advantageous given many viral genomes may not tolerate large nucleotide insertions into their sequences. [ABSTRACT FROM AUTHOR]

Abstract: There is increasing interest in using live cell imaging to monitor not just individual intracellular endpoints, but to investigate the interplay between multiple molecular events as they unfold in real time within the cell. A major impediment to simultaneous acquisition of fluorescent signals from multiple probes is that emission spectra of many fluorophores overlap, often with maxima that are only a few nanometers apart. Spectral acquisition of mixed fluorescence signals captured within a dedicated scanning range can be used to quantitatively separate signals into component spectra. We report here the development of a novel live cell application of spectral unmixing for the simultaneous monitoring of intracellular events reported by closely-emitting fluorophores responding dynamically to external stimuli. We validate the performance of dynamic spectral unmixing microscopy (DynSUM) using genetically encoded sensors to simultaneously monitor changes in glutathione redox potential (Egsh) and H2O2 production in living cells exposed to oxidizing and reducing agents. We further demonstrate the utility of the DynSUM approach to observe the relationship between the increases in Egsh and H2O2 generation induced in airway epithelial cells exposed to an environmental electrophile. [Copyright &y& Elsevier]

Fluorescence in situ hybridization is a widely used technique in cell biology providing insight into the spatial organization of specific RNA transcripts in the cell nucleus. However, to further investigate the dynamics of the transcription process and the transport rates of RNAs through the nucleus, RNAs need to be visualized and tracked in the living cell. In past years, various methods have been developed with the aim of tagging specific RNAs with a fluorescent moiety without interfering with cell vitality. These methods include the delivery of probes into a living cell, the in vivo hybridization of fluorescent oligonucleotide probes to endogenous RNAs, and the microscopic imaging of the tagged RNAs in living cells. In this article, we review a number of methods for tagging and visualizing endogenous RNAs in living cells. In addition, a protocol is described that allows detection of various RNA types using fluorochrome-labeled 2′-O-methyl oligoribonucleotide (2′-OMe RNA) probes. Compared with conventional oligodeoxynucleotide probes, 2′-OMe RNA probes are not degraded by nucleases, form stable hybrids with structured RNAs, and do not interfere with cell vitality. [Copyright &y& Elsevier]