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Fluorescent hypochlorite probes with ratiometric imaging ability are highly desirable for imaging hypochlorite in biological systems. However, it is still challenging to develop new scaffolds for these probes. In this study, we demonstrate that phenothiazine-fused boron complexes are promising scaffolds for the design of ratiometric fluorescent hypochlorite probes. The synthesized complexes based on the scaffold show ultrafast and ratiometric absorption/fluorescence changes for hypochlorite. We also developed an endoplasmic reticulum-targeting probe and demonstrated that it has excellent real-time imaging ability for both endogenous and exogenous hypochlorite in the endoplasmic reticulum of living cells. [ABSTRACT FROM AUTHOR]

Fluorescent sensing of formaldehyde (FA) in the environment is of great significance for human health. However, the development of ratiometric fluorescent probes for ultrasensitive FA detection is challenging due to the lack of suitable strategies. In this study, we demonstrate that ratiometric FA nanoprobes can be facile constructed by integrating two simultaneously excitable fluorophores into a polymer matrix. Using this strategy, we developed a ratiometric fluorescent nanoprobe (Nano‐FAP‐1) for the highly sensitive detection of FA in environmental samples by incorporating a 4‐hydrazino‐1,8‐naphthalimide derivative (Na‐FA) as the receptor and 7‐diethylaminocoumarin‐3‐carboxyl ethyl acetate (Cou‐1) as the reference into a Pluronic F‐127 matrix. The probe achieved a highly sensitive and selective response to low concentrations of FA, with a response time of fewer than 5 s and a detection limit of 0.407 μM. It is worth noting that the probe can be used for the determination of FA in wood and food samples, demonstrating its potential application in the field of toxic gas monitoring and environmental protection. [ABSTRACT FROM AUTHOR]

A novel fluorescent probe 2-(4-(diethylamino)-2-hydroxybenzylidene)-N-(2,3,3-trimethylbicyclo[2.2.1]heptan-2-yl)hydrazinecarbothioamide (HT) was prepared in this study by a condensation reaction. HT has been confirmed to possess high specificity toward Ga3+ over other metal ions (including Al3+ and In3+) via a distinct fluorescence light-up response. Moreover, HT exhibited good detection performances for Ga3+ including high selectivity, excellent anti-interference ability, a wide working pH range, and good reversibility. The association constant and limit of detection (LOD) were calculated to be 5.34 × 103 M−1 and 1.18 × 10−6 M, respectively. The detection mechanism of HT toward Ga3+ was proposed and confirmed by 1H NMR analysis, HRMS analysis, and DFT calculations. A simple test strip-based portable detecting device and a molecular INHIBIT logic circuit were established for improving its practical applicability. Furthermore, the desirable sensing performance of HT for Ga3+ was successfully reconfirmed in MCF-7 cells and zebrafish. [ABSTRACT FROM AUTHOR]

Reversible NIR luminescent probes with negligible photocytotoxicity are required for long-term tracking of cycling hypoxia in vivo. However, almost all of the reported organic fluorescent hypoxia probes reported until now were irreversible. Here we report a reversible arylazo-conjugated fluorescent probe (HDSF) for cycling hypoxia imaging. HDSF displays an off-on fluorescence switch at 705 nm in normoxia-hypoxia cycles. Mass spectroscopic and theoretical studies confirm that the reversible sensing behavior is attributed to the two electron-withdrawing trifluoromethyl groups, which stabilizes the reduction intermediate phenylhydrazine and blocks the further reductive decomposition. Cycling hypoxia monitoring in cells and zebrafish embryos is realized by HDSF using confocal imaging. Moreover, hypoxic solid tumors are visualized and the ischemia-reperfusion process in mice is monitored in real-time. This work provides an effective strategy to construct organic fluorescent probes for cycling hypoxia imaging and paves the way for the study of cycling hypoxia biology. Most fluorescence probes to measure hypoxia are irreversible. Here, the authors develop a near infrared luminescent probe to measure hypoxia which is reversible and use the probe to monitor hypoxia-reoxygenation in several animal models. [ABSTRACT FROM AUTHOR]

Due to the similar structure and reactivity of cysteine (Cys), homocysteine (Hcy) and glutathione (GSH), the simultaneous discrimination of Cys over Hcy and GSH by a single fluorescent sensor is still a great challenge. In this work, a benzothiazole-pyimidine-based boron difluoride complex ( BPB) was developed as a new fluorescent sensor for Cys. The sensor exhibits a highly selective 'turn-on' response to cysteine over Hcy, GSH and other amino acids in aqueous solution at physiological pH. The observed pseudo-first-order rate constant for the reaction of BPB with Cys was calculated to be about 0.062 min−1. The detection limit of this sensor for Cys was determined to be 332 n m, and bioimaging of exogenous Cys by this sensor was successfully applied in living cells, thus indicating that this sensor holds great potential for biological applications. [ABSTRACT FROM AUTHOR]

A BODIPY-based NIR fluorescent probe, NitroxylBDP , for the rapid and specific, detection of HNO has been designed and synthesized. The merits of NIR fluorescence, and stable fluorescence output against pH changes, and good membrane permeability, enable the probe to serve as an ideal indicator for tracking HNO in living systems. Unlabelled Image • A new NIR fluorogenic probe (NitroxyBDP) for detecting HNO was developed. • NitroxyBDP shows specific HNO-induced NIR emission "turn-on". • NitroxyBDP has been utilized to realize the HNO imaging in living HeLa cells. [ABSTRACT FROM AUTHOR]

Ratiometric near-infrared fluorescent probes are powerful tools for studying the biological roles of hypochlorite in biological systems. However, due to the lack of suitable fluorescent molecular platforms, the development of near-infrared ratiometric hypochlorite probes remains a challenge. Here, we report the design and synthesis of a near-infrared fluorescent probe PTZCy , which is constructed using a phenothiazine-hemicyanine hybrid framework. The incorporation of phenothiazine into the hemicyanine scaffold enables the probe to exhibit a near-infrared emission maximum at approximately 820 nm, along with a rapid and highly selective ratiometric response to hypochlorite. Importantly, PTZCy can be used to image both endogenous and exogenous hypochlorite in RAW264.7 cells, as well as to perform ratiometric imaging of hypochlorite during the acute liver injury process in living mice. [Display omitted] • A phenothiazine-hemicyanine hybrid framework was rationally designed for detecting ClO−. • The probe exhibited an emission maximum at 820 nm, along with a rapid and highly selective ratiometric response to ClO−. • The probe was employed for ratiometric imaging of ClO− in living cells and in mice experiencing acute liver injury. [ABSTRACT FROM AUTHOR]

Despite the huge contribution of membrane-based brine and wastewater purification systems in today's life, biofouling still affects sustainability of membrane engineering. Aimed at reducing membrane modules wastage, the need to study biofouling monitoring as one of contributory factors stemmed from the short time between initial attachment and irreversible biofoulant adhesion. Hence, a membrane for monitoring is introduced to determine the right cleaning time by using fluorescent sensing as a non-destructive and scalable approach. The classical solid-state emissive fluorophore, tetraphenylethylene (TPE), was introduced as a sustainable, safe and sensitive fluorescent indicator in order to show the potential of the method, and polyethersulfone (PES) and nonsolvent-induced phase separation method, the most popular material and method, are used to fabricate membrane in industry and academia. Since the employed filler has an aggregation-induced emission (AIE) characteristic, it can track the biofouling throughout the operation. The fabricated membranes have certain characterizations (i.e. morphology assessment, flux, antibiogram, flow cytometry, surface free energy, and protein adsorption) which indicate that hybrid membrane with 5 wt % of TPE has identical biofouling activity compared to neat PES membrane and its optimal luminescence properties make it an appropriate candidate for non-destructive and online biofouling monitoring. Image 1 • A multifunctional mixed matrix membrane for better understanding of biofouling is presented. • Employed filler has an aggregation-induced emission characteristic which can track the biofouling throughout the operation. • The obtained membranes revealed promising biofouling sensitivity. • The hybrid PES UF membrane with 5 wt % of TPE caused apparent biofouling detection. [ABSTRACT FROM AUTHOR]

As a reactive carbonyl molecule, formaldehyde (FA) plays an important part in plant physiological and pathological activities. It is necessary to probe FA in plant for the study of its functions. In this paper, we report DISE , a dicyanoisophorone-based turn-on near-infrared fluorescent probe, which exhibits a highly sensitive response to FA. In addition, confocal imaging experiments showed that DISE could image endogenous and exogenous FA in Arabidopsis root tissue. It demonstrates that the probe has the potential to be an imaging tool to research the FA's biological roles in plant. [Display omitted] • A new near-infrared fluorescence probe (DISE) towards to formaldehyde (FA) is reported. • DISE can selectively detect FA with a large Stokes shift and a large high emission enhancement factor. • DISE can monitor exogenous and endogenous FA in live Arabidopsis thaliana root tissues. [ABSTRACT FROM AUTHOR]

• A isophorone-based fluorescent probe for ratiometric imaging of methylglyoxal were developed. • The probes showed a highly sensitive and selective ratiometric response to methylglyoxal. • The probe has been applied in the ratiometric imaging of methylglyoxal in living cells. Fluorescent imaging of methylglyoxal (MGO) is essential for understanding the role of MGO played in cellular processes and pathogenesis. However, the development of fluorescent MGO probes with accurate imaging capabilities remains a challenge. In this study, we designed and synthesized an isophorone-based ratiometric fluorescent MGO probe for ratiometric imaging of MGO in living cells. The probe shows highly selective and sensitive response to MGO over other biological species. Notably, ratiometric fluorescent imaging of MGO in living HeLa cells demonstrates the promising imaging ability of the probe for studying the biological roles of MGO played in living cells. [ABSTRACT FROM AUTHOR]

Abstract Norfloxacin (NOR) in milk may influence mammalian cell replication and bring about a decrease in the efficiency for treating infection in humans. However, current techniques for detecting NOR usually require expensive instruments and trained personnel. In this work, we have developed a low-cost and simple method via paper-based fluorescent immunoassay for highly sensitive and selective detection of NOR in milk at picogram level. The NOR monoclonal antibody labeled with quantum dots is used as a detection probe to recognize the corresponding NOR, which can quantitatively detect NOR on paper-based devices. The detection limits in aqueous solution and milk are 1 pg/mL and 10 pg/mL, respectively. The developed paper-based method provides a cheap, sensitive, eco-friendly, and rapid approach for quantitative detection of trace NOR in milk, which may find wide applications in food safety inspection. Noteworthy, the method is especially suitable for applications at resource-limited and on-site settings. Graphical abstract fx1 Highlights • Paper-based fluorescent immunoassay using quantum dots-labeled antibody as probe. • Highly sensitive and selective detection of norfloxacin (NOR) in milk on paper. • The fluorescent intensity changes linearly with logarithm of NOR concentration. • The detection limits in solution and milk are 1 pg/mL and 10 pg/mL, respectively. • The paper-based method shows excellent selectivity for detection of NOR. [ABSTRACT FROM AUTHOR]

Hydrogen polysulfides (H 2 S n , n > 1) have attracted increasing attention in biological systems due to its redox signaling effect. To illustrate the process of the physiological and pathological roles played by H 2 S n , accurate detection is highly desired. In this work, we report a BODIPY-based fluorescent probe (BDP-PHS) for ratiometric H 2 S n sensing. BDP-PHS shows higher sensitivity and selectivity ratiometric response toward H 2 S n than various biological related species. Moreover, BDP-PHS has been successfully applied in imaging of H 2 S n in living cells. A new fluorescent probe, BDP-PHS , which exhibits a specific ratiometric response toward H 2 S n than various biological related species in both aqueous media and living cells was developed. Unlabelled Image • A new ratiometric fluorogenic probe (BDP-PHS) for detecting polysulfides was developed. • BDP-PHS shows specific polysulfides-induced emission shift from 574 to 593 nm. • BDP-PHS has been utilized to realize the in vivo ratiometric polysulfides imaging in living cells. [ABSTRACT FROM AUTHOR]