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A fluorescence-enhanced and lysosome-targeted Al3+ probe (1) based on a pyrazole-containing hydrazone was developed in this work. The fluorescent probe 1 displays an OFF–ON fluorescence response to Al3+ in the lysosome pH environment. In addition, the resultant 1 –Al3+ complex could act as an ON–OFF fluorescence sensor for F−. Fluorescence imaging shows that 1 is suitable for visualization of Al3+ in lysosomes of HeLa cells. Image 1 • A quite simple hydrazone-based fluorescent probe for Al3+ has been developed. • The probe displayed an OFF-ON response toward Al3+ in aqueous solution. • The resultant Al3+ complex of the probe could act as an on-off fluorescent sensor for F−. • The probe has been used for imaging of Al3+ in lysosomes of HeLa cells. [ABSTRACT FROM AUTHOR]

Abstract A new fluorescent probe was designed and synthesized according to the photo-induced electron transfer theory (PET) and the results of density functional theory calculation. The synthesized probe had a larger Stokes shift (130 nm) and double emission peak in response to highly toxic thiophenols, which could be applied in rapid and high sensitive detection of thiophenol in aqueous solution. A 25-fold fluorescence intensity enhancement was achieved and the fluorescent intensity at 460 nm had a linear relationship to the thiophenol in concentration range of 0–2.0 μM. Furthermore, a remarkable detection limit (6 nM) could be achieved. 50-fold other species have no interference to the detection. The practical utility of the probe was demonstrated by live HeLa cells imaging and thiophenol detection in real water samples. In linear range of 0–2.0 μM, the probe showed good recoveries (from 95% to 108%) for thiophenol detection in natural water samples. This method possesses high sensitivity, lower detection limit and fast response (i.e., 10 min, which is shorter than the average time response of other reported methods), indicating that the synthesized probe would be promising for real-time detection of thiophenols. Graphical abstract fx1 Highlights • DFT calculations were used to design a thiophenol sensor and understand the mechanism. • A novel double emission fluorescent probe BIN-T was synthesized and characterized. • BIN-T possesses high fluorescence quantum yield and fast response to thiophenol. • The probe can be applied in thiophenol assay in real water samples and bioimaging. [ABSTRACT FROM AUTHOR]

A simple naphthalene-based fluorescent probe ( AENO ) for formaldehyde (FA) was successfully synthesized, which exhibited a significant fluorescence turn-on response towards FA in aqueous solution. The probe could quantitatively determine the concentration of FA (0–1.0 mM) with excellent selectivity, high sensitivity and low limit of detection (0.57 µM). The sensing mechanism was proposed as 2-aza-Cope rearrangement for AENO after reaction with FA, which was confirmed by 1 H NMR, HR-MS, FT-IR, UV–vis and fluorescence spectra. The probe has been employed to determine the FA contents in several commercially available toffee samples with satisfactory performance. Thus, AENO might be used as a promising tool for quantitative detection of FA in food. Furthermore, fluorescence imaging of HeLa cells indicated that the probe was cell membrane permeable and could be used for visualizing/imaging the FA trace/transportation in cancer cells. [ABSTRACT FROM AUTHOR]