The whole picture: Carbon nanodots labeled with two fluorescent dyes have been developed as a tunable ratiometric pH sensor to measure intracellular pH. The nanosensor shows good biocompatibility and cellular dispersibility. Quantitative determinations on intact HeLa cells and pH fluctuations associated with oxidative stress were performed.
Solar CO reduction efficiency is largely limited by poor photoabsorption, sluggish electron-hole separation, and a high CO activation barrier. Defect engineering was employed to optimize these crucial processes. As a prototype, BiOBr atomic layers were fabricated and abundant oxygen vacancies were deliberately created on their surfaces. X-ray absorption near-edge structure and electron paramagnetic resonance spectra confirm the formation of oxygen vacancies. Theoretical calculations reveal the creation of new defect levels resulting from the oxygen vacancies, which extends the photoresponse into the visible-light region. The charge delocalization around the oxygen vacancies contributes to CO conversion into COOH* intermediate, which was confirmed by in situ Fourier-transform infrared spectroscopy. Surface photovoltage spectra and time-resolved fluorescence emission decay spectra indicate that the introduced oxygen vacancies promote the separation of carriers. As a result, the oxygen-deficient BiOBr atomic layers achieve visible-light-driven CO reduction with a CO formation rate of 87.4 μmol g h , which was not only 20 and 24 times higher than that of BiOBr atomic layers and bulk BiOBr, respectively, but also outperformed most previously reported single photocatalysts under comparable conditions.
Heat stroke is a life-threatening condition, featuring a high body temperature and malfunction of many organ systems. The relationship between heat shock and lysosomes is poorly understood, mainly because of the lack of a suitable research approach. Herein, by incorporating morpholine into a stable hemicyanine skeleton, we develop a new lysosome-targeting near-infrared ratiometric pH probe. In combination with fluorescence imaging, we show for the first time that the lysosomal pH value increases but never decreases during heat shock, which might result from lysosomal membrane permeabilization. We also demonstrate that this lysosomal pH rise is irreversible in living cells. Moreover, the probe is easy to synthesize, and shows superior overall analytical performance as compared to the existing commercial ones. This enhanced performance may enable it to be widely used in more lysosomal models of living cells and in further revealing the mechanisms underlying heat-related pathology.
A new rhodamine B-based fluorescent probe for the hypochlorite anion (OCl(-)) has been designed, synthesized, and characterized. The probe comprises a spectroscopic unit of rhodamine B and an OCl(-)-specific reactive moiety of dibenzoylhydrazine. The probe itself is nearly nonfluorescent because of its spirolactam structure. Upon reaction with OCl(-), however, a largely enhanced fluorescence is produced due to the opening of the spirolactam ring by the oxidation of the exocyclic hydrazide and subsequently the formation of the hydrolytic product rhodamine B. Most notably, the fluorescence-on reaction shows high sensitivity and extremely high selectivity for OCl(-) over other common ions and oxidants, which makes it possible for OCl(-) to be detected directly in their presence. In addition, the reaction mechanism has been investigated and proposed. The OCl(-) anion selectively oxidizes the hydrazo group in the probe, and forms the analogue of dibenzoyl diimide, which in turn hydrolyzes and releases the fluorophore. The reaction mechanism that is described here might be useful in developing excellent spectroscopic probes with cleavable active bonds for other species.
A highly selective and sensitive fluorescence probe, 7-[(5-nitrofuran-2-yl)methoxy]-3H-phenoxazin-3-one (1), is developed for imaging the hypoxic status of tumor cells via the indirect detection of nitroreductase. The detection mechanism is based on the fact that nitroreductase can selectively catalyze the reduction of the nitro group in 1 to a hydroxylamine or amino group in the presence of reduced nicotinamide adenine dinucleotide as an electron donor that is indispensable, followed by the 1,6-rearrangement-elimination and the release of resorufin. As a result, the reaction produces a distinct color and fluorescence change from almost colorless and nonfluorescent to pink and strong red fluorescence. The fluorescence increase of probe 1 at λ(550/585 nm) is directly proportional to the concentration of nitroreductase in the range of 15-300 ng/mL, with a detection limit of 0.27 ng/mL. The ready reduction of the nitro group in 1 under hypoxic conditions leads to the establishment of a sensitive and selective fluorescence method for imaging the hypoxic status of tumor cells, and with this method Hela and A549 cells under normoxic and hypoxic conditions (even for different extents of hypoxia) can be differentiated successfully. This method is simple and may be useful for the imaging of disease-relevant hypoxia.
sulfur species have received considerable attention due
to their various biological functions. Among these molecules, hydrogen
polysulfides (H2Sn, n > 1) are recently suggested to be the actual signaling
molecules derived from hydrogen sulfide (H2S). Hydrogen
polysulfides may also have their own biosynthetic pathways. The research
on H2Sn is rapidly growing.
However, the detection of H2Sn is still challenging. In this work we report a H2Sn-mediated benzodithiolone formation under
mild conditions. Based on this reaction, specific fluorescent probes
for H2Sn are prepared and evaluated.
The probe DSP-3 shows good selectivity and sensitivity
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