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[Display omitted] • A cyanine-based fluorescent probe (Cy-H) with built-in self-calibration ratio mode was successfully synthesized. • This probe Cy-H exhibits specific recognition performance for hypochlorite with an LOD of 0.49 μM. • The probe showed good biocompatibility and relatively low biological toxicity, and was successfully applied to the detection and analysis of ClO− labeled imaging in live cells and zebrafish. Hypochlorite (ClO−), a weakly acidic reactive oxygen species, plays a crucial role in antibacterial and anti-inflammatory defense mechanisms. However, elevated levels of ClO− or disruptions in endogenous sites can lead to tissue damage and various diseases including cardiovascular disease, neuronal degeneration, and arthritis. To address this, the development of a specific fluorescent probe with a built-in self-calibration ratio mode for the analysis and biological imaging of ClO− is essential. In this study, a cyanine-based fluorescent probe (Cy-H) was designed for ratiometric fluorescent detection of ClO−, utilizing its aggregation behavior as a novel approach in this field. Upon exposure to ClO−, the phenolic hydroxyl group in probe Cy-H was oxidized into benzoquinone, leading to the formation of cyanine products that displayed a strong tendency to aggregate. As a result, the maximum emission peak of the probe shifted from 700 nm to 485 nm. Notably, a linear relationship was observed between the peak intensity ratio (I 485 /I 700) and the concentration of hypochlorite, with a limit of detection (LOD) of 0.49 μM. Furthermore, this probe was successfully employed for imaging analysis of hypochlorite in living cells and zebrafish. [ABSTRACT FROM AUTHOR]

Reported here is a novel ratiometric and colorimetric fluorescent probe 1 for hypochlorite based on cyanobiphenyl and diaminomaleonitrile. This probe 1 was designed based on the mechanism that ClO− selectively cleaved the hydrazone bond (-C=N-) in this probe and released the fluorophore, 3'-formyl-4'-hydroxy-4-biphenylcarbonitrile. The addition of ClO− to the solution of probe 1 resulted in a very large blue-shift in both fluorescence (107 nm) spectra and an obvious fluorescence color change from red to green. Furthermore, this probe displays a rapid response (30 s) and a low detection limit (3.34 × 10−7 M, based on LOD = 3σ/slope) in detecting ClO−. Importantly, practical utility of this probe for the selective detection of ClO− in living cells has been successfully demonstrated, illustrating the great potential for biological analysis. Additionally, the probe 1 was also successfully applied to the detection of ClO− in real water sample. Unlabelled Image • A ratiometric and colorimetric fluorescent probe for ClO− was designed and synthesized. • The addition of ClO− resulted in a very large blue-shift in emission spectra and an obvious fluorescence color change. • This probe displays a rapid response and a low detection limit in detecting ClO−. • This probe for the selective detection of ClO− in living cells has been successfully demonstrated. • The probe 1 was also successfully applied to the detection of ClO− in real water sample. [ABSTRACT FROM AUTHOR]

Abstract A novel fluorescence probe L2 based on coumarin has been designed and synthesized. The probe L2 can be used for relay recognition of metal ions Al3+ and anion F− in the aqueous HEPES buffer (0.05 M, pH = 7.4), and build a OFF-ON-OFF detection system. The probe showed high selectivity and sensitivity to target ions in the process of relay recognition, and the corresponding detection limit could be as low as 0.014 μM (Al3+) and 0.03 μM (F−). Besides, the geometry optimizations of probe L2 and [L2 + Al3+] complex were carried out using the Gaussian 16 program based on DFT, and the identification mechanism of the probe was also discussed by the mass spectrometry and theoretical calculations. Moreover, the probe has also been successfully applied to detection of target ions in living cells. Graphical Abstract Unlabelled Image Highlights • A novel fluorescence probe L2 based on coumarin has been designed and synthesized. • The probe L2 can be used for relay recognition of metal ions Al3+ and anion F− and build an OFF-ON-OFF detection system. • The corresponding detection limit could be as low as 0.014 μM (Al3+) and 0.03 μM (F−) • The probe have also been successfully applied to detection of target ions in living cells. [ABSTRACT FROM AUTHOR]

A fluorescence probe (HBM) based on conjugation of 3′-formyl-4′-hydroxy-4-biphenylcarbonitrile to 2,4-dinitrophenylhydrazune for the detection of hypochlorite has been developed. The probe exhibited a highly sensitive and selective response toward hypochlorite (ClO − ) with a low detection limit of 49 nM. The sensing mechanism was considered that the hypochlorite triggered oxidative hydrolysis of probe HBM and the cyanobiphenyl fluorophore was released, which also have been evidenced by the MS analysis. Most notably, the response time of the probe HBM to the OCl − is only a few seconds. The probe was also successfully applied to fluorescence imaging of OCl − in the living cells. [ABSTRACT FROM AUTHOR]

At present, the design of multi ion sensing receptors is a new area of research due to their potential application in the recognition of analytes. Herein, a novel fluorescent probe for the detection of multi metal ions was designed and synthesized based on the fluorophores of biphenyl and rhodamine. Probe 1 exhibits multiple fluorescence responses to various metal ions (Zn2+, Al3+, Cr3+ and Fe3+) and is accompanied by different optical signal outputs. Moreover, the interference between the target ions can also be effectively solved by the introduction of probe 2 and the addition of the corresponding anions. Probe 1 was also successfully used to detect trace metal ions in real water samples and silicone plate test strips were prepared for the rapid qualitative detection of target metal ions. In addition, in order to better understand the multiple response mechanism of probe 1, geometry optimizations and electronic calculations were carried out at the B3LYP/6-31G*/LANL2DZ level of theory. And harmonic vibrational frequency calculations were also carried out to ensure that all optimized structures were at energy minima on the potential energy surface. [ABSTRACT FROM AUTHOR]

A simple relay identification fluorescence probe for Fe 3 + and phosphate anion with “on-off-on” switching was designed and synthesized based on the phenylthiazole and biphenylcarbonitrile. Probe 1 displayed highly selective and sensitive recognition to Fe 3 + in HEPES aqueous buffer (EtOH/H 2 O = 2:8, v/v, pH = 7.4) solutions. The optimized structures and HOMO and LUMO of probe 1 and [1-Fe 3 + ] complex were obtained by the density functional theory (DFT) calculations with B3LYP as the exchange and correlation functional using a suite of Gaussian 09 programs. The [1-Fe 3 + ] complex solution also showed a high selectivity toward PO 4 3 − . The lower limits of detection of probe 1 to Fe 3 + and [1-Fe 3 + ] complex to PO 4 3 − were estimated to 1.09 × 10 − 7 M and 1.86 × 10 − 7 M. Besides, the probe 1 also was used to detected the target ions in real water sample and living cells successfully. [ABSTRACT FROM AUTHOR]

A fluorescence probe has been designed and synthesized, and applied with a combined theoretical and experimental study. Research suggests that the probe can be used to sense Zn 2 + and Hg 2 + through selective turn-on fluorescence responses in the aqueous HEPES buffer (0.05M, pH = 7.4). The limit of detection (LOD) were determined as 1.46 × 10 − 7 M (Zn 2 + ) and 2.50 × 10 − 7 M (Hg 2 + ). Moreover, based on DFT, the geometry optimizations of probe 1, [1-Hg 2 + ] complex and [1-Zn 2 + ] complex were carried out using the Gaussian 09 program, in which the B3LYP function was used. The electronic properties of free probe 1 and the metal complexes were studied based on the Natural Bond Orbital (NBO) analyses. The probe 1 has also been successfully applied to detection of Zn 2 + and Hg 2 + in living cells. [ABSTRACT FROM AUTHOR]

A novel fluorescent probe XDS based on 4-methylumbelliferone and 2-picolylamine platforms has been designed and synthesized, which behaves fast relay recognition of Fe 3+ and PO 4 3− via a fluorescence “on−off−on” response signal. Probe XDS exhibited very high sensitivity and unique selectivity for Fe 3+ over other common metal ions, and the detection limit of was 3.2 × 10 −7 M. Moreover, the addition of the PO 4 3− ions could cause the recovery of fluorescence. This relay recognition feature of probe XDS has potential applications in the determination of trace amount of Fe 3+ and PO 4 3− in environmental systems. Interestingly, fluorescence imaging experiments demonstrated that the probe XDS can also be used to monitoring the intracellular Fe 3+ in RAMOS cells. [ABSTRACT FROM AUTHOR]

A new on-off fluorescent probe 1 for Cu 2+ based on Schiff base compound was designed and synthesized by one-step reaction. The single probe 1 exhibited strong green fluorescence emission. A fluorescence quenching effect and faint color change were observed as soon as the Cu 2+ was added to the probe system in H 2 O/EtOH (v/v = 8:2, HEPES buffer, 0.05 M, pH = 7.4) solution. Other common metal cations did not cause the changes in the fluorescence and color of the probe 1. The optical properties were studied by the fluorescence emission and UV–Vis spectra. Meanwhile, the geometry optimizations of probe 1 and the [1-Cu 2+ ] coordination complexes were also carried out by DFT using the Gaussian 09 program, in which the B3LYP function was used. Based on experimental measurement and theoretical analysis, we can know that the combination ratio of the probe and Cu 2+ is 2:1 and the limit of detection (LOD) is as low as 5.3 × 10 −9 M Besides, the probe 1 was also used to analyze the Cu 2+ in living cells. [ABSTRACT FROM AUTHOR]

A novel quinazolinone based turn-on fluorescence probe for sensitive monitoring hypochlorite was prepared using the mild condensation reaction between 2-(2′-hydroxyphenyl)-4(3H)-quinazolinone derivative and 4-methylbenzenesulfonyl hydrazide. The probe exhibited specific selectivity to ClO− with obvious optical signal changes from weak fluorescence at 560 nm to a strong fluorescence emission at 520 nm and color changes from colorless to yellow, which could be noticed by the naked eye. The detection limit toward hypochlorite is as low as 11.4 nM. Moreover, the probe could sensitively response to ClO− in living cells with satisfying imaging effect and has been successfully applied to the determination of ClO− in practical water samples, which indicated that the probe has certain application potential for hypochlorite monitoring. Unlabelled Image • A quinazolinone based fluorescent probe for detection of ClO− was designed and synthesized. • Probe QBH showed a rapid and remarkable fluorescence "turn-on" response to ClO−. • The QBH could detect ClO− quantitatively with a detection limit as low as 11.4 nM. • The sensing mechanism is analyzed through the NMR and MS spectra. • The probe was successfully applied to the determination of ClO− in practical water samples. [ABSTRACT FROM AUTHOR]

Hypochlorite is an important biological reactive oxygen species, which plays a pivotal role in various life activities. Excessive presence in the human body or excessive intake in life causes a series of diseases. To monitor the hypochlorite level in living cells, organisms and environment water samples, we herein designed and synthesized three organic small molecule fluorescent probes with different recognition sites based on nitrile biphenyl. Through performance comparison, it was found that probe A-HM exhibited the best detection performance for hypochlorite with a low detection limit of 2.47 × 10–6 M. The introduction of hypochlorite will induce probe fluorescence A-HM to turn on, and the fluorescence colour will change from colourless to green. The application of A-HM in biological systems has been demonstrated by the imaging monitoring of hypochlorite in MCF-7, L929 cells and zebrafish. Furthermore, A-HM was also used for the accurate determination of the hypochlorite level in real water samples with high sensitivity and good recoveries. [ABSTRACT FROM AUTHOR]

[Display omitted] • Organic small molecule fluorescent probes for the specific recognition of Cys were designed and synthesised on the basis of nitrile biphenyls. • The detection of Cys by probe ZHJ-X was studied systematically. • Probe ZHJ-X can be used for specific recognition of Cys with more rapid and efficient detection ability, the corresponding detection limit could be as low as 3.8 × 10-6 M. • The probe has also been successfully applied to detection of target ions in MCF-7 cells、HL60 cells and zebrafish. Cys play an important physiological role in the human body. Abnormal Cys concentration can cause many diseases. Therefore, it is of great significance to detect Cys with high selectivity and sensitivity in vivo. Because homocysteine (Hcy) and glutathione (GSH) have similar reactivity and structure to cysteine, few fluorescent probes have been reported to be specific and efficient for cysteine. In this study, we designed and synthesized an organic small molecule fluorescent probe ZHJ-X based on cyanobiphenyl, which can be used to specifically recognize cysteine. The probe ZHJ-X exhibits specific selectivity for cysteine, high sensitivity, short reaction response time, good anti-interference ability, and has a low detection limit of 3.8 × 10-6 M. The probe ZHJ-X was successfully applied to the visualization of Cys in living cells and had great application prospects in cell imaging and detection. [ABSTRACT FROM AUTHOR]

A fluorescent probe composed of BODIPY and 2,4-dinitrophenylhydrazine was designed for the detection of ClO − . The oxidizing reaction between probe and ClO − resulted in a distinct fluorescence enhancement together with a color variation from pink to orange. This probe showed excellent selectivity to ClO − among various ions including common reactive oxygen species and high sensitivity with a detection limit of 228 nM. A fast response (7 min) was observed, which made the probe a promising method in real-time detection. Furthermore, this probe was successfully applied to monitor ClO − in real-life water and living cells. [ABSTRACT FROM AUTHOR]

Hypochlorite serves as a powerful antimicrobial agent in human immune system, the detection of which is of great significance. Herein a novel fluorescent probe based on BODIPY dye and diaminomaleonitrile has been synthesized and characterized to sense hypochlorite. The fluorescence of the system is dramatically enhanced by ClO − due to the removal of C=N isomerization effect in physiological pH condition. The complete reaction only needs a few seconds, which enables the probe to facilitate real-time detection. This probe also has satisfactory selectivity for ClO − even in the presence of other interferential ions and shows high sensitivity with a detection limit of 19.8 nM. Furthermore, Probe 1 has been successfully applied to detect ClO − in real water samples. [ABSTRACT FROM AUTHOR]