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Monitoring hydrogen sulfide (H2S) in living organisms is very important because H2S acts as a regulator in many physiological and pathological processes. Upregulation of endogenous H2S concentration has been shown to be closely related to the occurrence and development of tumors, atherosclerosis, neurodegenerative diseases and diabetes. Herin, a novel fluorescent probe HND with aggregation-induced emission was designed. Impressively, HND exhibited a high selectivity, fast response (1 min) and low detection limit (0.61 μM) for H2S in PBS buffer (10 mM, pH = 7.42). Moreover, the reaction mechanism between HND and H2S was conducted by Job's plot, HR-MS, and DFT. In particular, HND was successfully employed to detect H2S in HeLa cells. [ABSTRACT FROM AUTHOR]

Biothiols, including cysteine (Cys), homocysteine (Hcy), and glutathione (GSH), play key roles in biological processes, and detecting such thiols selectively is critical for understanding functions of biothiols. In this work, a pyridazine annelated perylene–based fluorescent probe PAPC is synthesized for highly selective detection of Cys. PAPC exhibits strong blue emission in PBS, while the red emission at 605 nm can be observed in the presence of Cys. The probe PAPC shows ratiometric fluorescence (I605/I460) detection of Cys with wide linear range of 1–120 μM and low detection limit of 0.19 μM. Super large Stokes shift (170 nm) and ratiometric fluorescence endow the probe low background signal. The discrimination of Cys over Hcy and GSH can be achieved through the difference of the ratiometric fluorescence. In addition, the probe has been proven to track Cys in real samples such as urine and HeLa cells. Therefore, PAPC probe is a promising candidate for detecting Cys in practical application. [ABSTRACT FROM AUTHOR]

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]

A new colorimetric and fluorescence probe NRSH based on Nile-red chromophore for the detection of biothiols has been developed, exhibiting high selectivity towards biothiols over other interfering species. NRSH shows a blue shift in absorption peak upon reacting with biothiols, from 587 nm to 567 nm, which induces an obvious color change from blue to pink and exhibits a 35-fold fluorescence enhancement at 645 nm in red emission range. NRSH displays rapid (<1 min) response for H2S, which is faster than other biothiols (>5 min). The detection limits of probe NRSH towards biothiols are very low (22.05 nM for H2S, 34.04 nM for Cys, 107.28 nM for GSH and 113.65 nM for Hcy). Furthermore, NRSH is low cytotoxic and can be successfully applied as a bioimaging tool for real-time monitoring biothiols in HeLa cells. In addition, fluorescence mechanism of probe NRSH is further understood by theoretical calculations. [ABSTRACT FROM AUTHOR]

A colorimetric and ratiometric fluorescent probe DTF for HSO 3 − was synthesized from natural and renewable nopinone. The fluorescent probe DTF can quantitatively detect HSO 3 − with high selectivity, sensitivity and fast response time (60 s). The detection process was accompanied with the visible color change from yellow to colorless and the fluorescent color change from green to blue. The fluorescence intensity ratio (F 430 /F 520) was linear with the concentration of HSO 3 − in the range of 0–80 μM, with a limit detection of 79.2 nM. The sensing mechanism was confirmed by 1H NMR and HRMS spectra. Above all, the novel fluorescent probe DTF was successfully applied to determine the concentration of HSO 3 − in food samples and HeLa cells. In this manuscript, we designed and synthesized a novel nopinone-based fluorescence probe for colorimetric and ratiometric detection of HSO 3 −, with high sensitivity, good selectivity and fast response time. The novel probe DTF was successfully applied for detection of the concentration of HSO 3 − in food samples and living HeLa cells. Image 1 • This is the first report that the synthesis of HSO 3 −-specific fluorescence probe based on nopinone. • The colorimetric and ratiometric fluorescent probe DTF can quantitatively detect HSO 3 − with high selectivity, sensitivity and fast response time. • Probe DTF was successfully applied for detection of the concentration of HSO 3 − in food samples and living HeLa cells. [ABSTRACT FROM AUTHOR]