A Halloysite Nanotubes-based Probe for Efficient Fluorescence Detection and Adsorption Removal of Pb2+ in Water.

The detection and removal of Pb2+ is of utmost importance for environmental protection and human health due to its toxicity, persistent pollution, and bioaccumulation effects. To address the limitations associated with organic small molecule-based fluorescence probes such as poor water solubility and single functionality in detecting Pb2+, a fluorescence probe based on halloysite nanotubes was developed. This probe not only enables specific, rapid, and reliable detection of Pb2+ but also facilitates efficient removal of it from water. The development of this bifunctional fluorescent probe provides a valuable insight for designing more advanced probes targeting heavy metal ions.

Recent Advances in Organic Small-Molecule Fluorescent Probes for the Detection of Zinc Ions (Zn2+).

Zinc(II) ions (Zn2g) play crucial roles in the growth, propagation, and metabolism of animals, plants, and humans. Abnormal concentrations of Zn2+ in the environment and living organisms pose potential risks to environmental protection and human health. Therefore, it is imperative to develop rapid, reliable and in-situ detection methods for Zn2+ in both environmental and biological contexts. Furthermore, effective analytical methods are required for diagnosing diseases and understanding physiological metabolic mechanisms associated with Zn2+ concentration levels. Organic small-molecule fluorescent probes offer advantages such as fast, reliable, convenient, non-destructive detection capabilities and have significant application potential in Zn2+ detection and bioimaging; thus garnering extensive attention. Over the past two years alone, various organic small-molecule probes for Zn2+ based on different detection mechanisms and fluorophores have been rapidly developed. However, these probes still exhibit several limitations that need further resolution. In light of this context, we provide a comprehensive summary of the detection mechanisms, performance characteristics, and application scope of Zn2+ fluorescence probes since year 2022 while highlighting their advantages. We also propose solutions to address existing issues with these probes and outline future directions for their advancement. This review aims to serve as a valuable reference source offering insights into the development of advanced organic small-molecule-based fluorescence probes specifically designed for detecting Zn2+.

A near-infrared Fluorescent Probe Based on Dicyanisophorone for the Detection of Zinc Ions (Zn2+) in Water and Living Cells.

As one of the important metal ions, zinc ions (Zn2+) are widely involved in various physiological and pathological processes, and play fundamental roles in neurotransmission, cell metabolism and apoptosis. However, the convenient monitor of Zn2+ in environmental and biological samples remains challenging. In this study, a small molecule dicyanoisophorone-based schiff base incorporating with o-phenylenediamine was synthesized. It can rapidly combine with Zn2+ to emit significant near-infrared fluorescence (maximum emission wavelength: 660 nm), so it can be used as a probe to quantitatively detect Zn2+ in the range of 0-10 µM, with a detection limit as low as 4.8 nM, showing the probe has high sensitivity for Zn2+. And the probe has a fast response time to Zn2+ (less than 30 s) and a large Stoke-shift (179 nm). In addition, the high recovery rates in practical water samples, and the clear fluorescent images in living A549 cells were obtained, which are of great significance for the detection of Zn2+ in the environment and biosystem. Due to its simple operation, good selectivity and anti-interference ability, short detection time and high sensitivity, this probe has great application potential as a fast detection tool for Zn2+ in environmental water and biological samples.

Molecular Engineering to Achieve AIE-active Fluorophore with Near-infrared (NIR) Emission and Temperature-sensitive Property.

Near-infrared organic small molecule luminescent materials have the advantages of easy modification, high quantum efficiency, good biological affinity, and color adjustability; thus, have promising application prospects in the fields of photoelectric devices, sensitive detection, photodynamic therapy, and biomedical imaging. However, traditional organic luminescent molecules have the problems of short emission wavelength, aggregation-causing emission quenching, and low quantum yield. Herein, we successfully synthesized four D-π-A-D light-emitting molecules based on electron-withdrawing malonitrile group and different electron-donating arylamine groups. These compounds showed satisfactory solvatochromism, aggregation-induced emission, red and near-infrared fluorescence, high photoluminescence quantum efficiency and temperature response properties. This successful example of molecular engineering provides a valuable reference for the development of advanced NIR materials with AIE and temperature-sensitive properties.

A Dicyanoisoflurone-based Near-infrared Fluorescence Probe for Highly Sensitive Detection of Hg2.

Due to its high toxicity, long durability, easy absorption by aquatic organisms, and significant bioaccumulation, Hg2+ has caused substantial environmental damage and posed serious threats to human health. Therefore, effective detection of Hg2+ is of utmost importance. In this study, a turn-on fluorescent probe based on dicyanoisoflurone was developed for the detection of Hg2+. The probe exhibited near-infrared fluorescence signal at 660 nm upon excitation by 440 nm UV light in a mixture of CH3CN and HEPES buffer (4:1, v/v, 10 mM, pH = 7.5), with selective binding to Hg2+ in a molar ratio of 1:1. This binding event was accompanied by a visible color change from light yellow to orange. By utilizing the enhanced fluorescence signal change, this probe enables highly sensitive analysis and detection of Hg2+ with excellent selectivity (association constant = 1.63 × 104 M- 1), large Stokes shift (220 nm), high sensitivity (detection limit as low as 5.6 nM), short reaction time (30 s), and a physiological pH range of 7.5-9.5. The probe was successfully employed for detecting of Hg2+ in real water and living cells.

Analysis of HLA Profiles in 390 Uveitis Cases: Insights into Clinical Presentations.

Objective: This study aimed to explain the associations between different types of uveitis and human leukocyte antigen (HLA)-B27, HLA-DR4, and HLA-DRw53. Methods: A retrospective analysis of 390 uveitis cases was conducted among inpatients and outpatients diagnosed at Weifang Eye Hospital from 2013 to 2016. All 390 patients underwent HLA-B27 examination, and an additional 40 patients underwent examination for HLA-DR4 and HLA-DRw53. Gender, age, corrected visual acuity (CVA), and recurrence frequency were statistically analyzed based on the onset site and etiology classification. Results: Among the 390 enrolled patients, 206 were male, and 183 were female, with ages ranging from 6 to 87 years (mean: 44.2). The disease onset was classified into anterior uveitis (AU), panuveitis (panU), posterior uveitis (PU), and intermediate uveitis in 180, 112, 88, and 10 cases, respectively. HLA-B27 was positive in 94 cases (53 males and 41 females), yielding a positive rate of 24.1%. In AU patients, 80 (44.4%) tested positive for HLA-B27, while 8 (7.1%) panU patients and 6 PU patients (6.8%) were HLA-B27 positive; none of the intermediate uveitis (IU) patients exhibited HLA-B27 positivity. HLA-B27, HLA-DR4, and HLA-DRw53 examinations were performed on 40 patients with binocular uveitis, resulting in 2 HLA-B27 positive cases, 15 HLA-DR4 positive cases, and 20 HLA-DRw53 positive cases, with positive rates of 5%, 37.5%, and 50%, respectively. Among 25 Vogt Koyanagi-Harada (VKH) cases, 1 tested positive for HLA-B27, 22 were positive for HLA-DR4, and 24 were positive for HLA-DRw53, with positive rates of 4%, 88%, and 96%, respectively. No positive HLA-B27, HLA-DR4, or HLA-DRw53 cases were found among the 10 cases of Behcet's disease (BD). Conclusions: Human leukocyte antigens (HLAs) play a significant role in the mechanism of uveitis. HLA-B27 exhibits high diagnostic value in acute AU, while HLA-DR4 and HLA-DRw53 are crucial for diagnosing binocular uveitis, particularly Vogt Koyanagi-Harada (VKH) syndrome. Further investigation is warranted to explore the relationship between HLA-DR4, HLA-DRw53, and uveitis.

A metal-free coumarin-based fluorescent probe for the turn-on monitoring of carbon monoxide in an aqueous solution and living cells.

Endogenous carbon monoxide (CO) is an essential cell signaling molecule, which is closely related to numerous physiological and pathological processes. Therefore, it is of great significance to monitor CO in living samples. Fluorescent probe technique provides an effective and convenient method for monitoring CO. Although many fluorescent probes of CO have been reported, most of them require the introduction of heavy metal ions (Pd2+), which is not conducive to the practical application of these probes. Herein, a metal-free coumarin-based fluorescent probe was developed for monitoring CO. For this probe, coumarin was selected as the fluorophore, the aromatic nitro group was used as the reactive site, and the carboxyl moiety acted as the water-soluble unit. As a result, this probe has been proved to be able to monitor CO with good specificity and excellent sensitivity in water medium. After interacting with CO, the aromatic group was reduced to an aryl amino group; accordingly, the emission intensity of the peak corresponding to the probe at 450 nm significantly increased. Moreover, it successfully realized the detection of CO in living cells by a fluorescence signal.

A 2-Hydroxy-1-naphthaldehyde Schiff Base for Turn-on Fluorescence Detection of Zn2+ Based on PET Mechanism.

Zinc ion is closely related to human health. Its content in human body is small, while the effect is large. However, it is not the more the better, must be in a scientific balance. Therefore, it is significant to the rapid detection of Zn2+ in the environment and organism. Herein, a fluorescent probe based on 2-hydroxy-1-naphthalene formaldehyde and furan-2-carbohydrazide was conveniently synthesized via Schiff base reaction. And this probe has been successfully applied to the accurate and quantitative detection of Zn2+ in real samples, showing turn on fluorescence, good selectivity, very low detection limit, real time response and reusability. In addition, this probe has the potential application to trace Zn2+ in living cells with low cytotoxicity.

A Fluorescent Probe for the Fast Detection of Hypochlorite and its Applications in Water, Test Strip and Living Cells.

Hypochlorite (ClO-) mediated by oxidative stress play an important role in the body's defense system due to their physiological and pathological significance. In this work, a new and simple probe was designed and synthesized to detect hypochlorite. This probe could rapidly respond to hypochlorite in a short time (20 s) in aqueous media, and showed excellent selectivity and sensitivity, and a wide pH range of 3 ̶ 12, as well as the low detection limit of 1.44 nM. In addition, it was successfully applied to the detection of ClO- in water sample, test paper experiment, and cell imaging.

A ratiometric fluorescent probe for the rapid and specific detection of HSO3 - in water samples.

Hydrosulphite (HSO3 - ), as a common and important chemical reagent, is widely used in everyday life, however excessive use and abuse of HSO3 - can cause potential harmful effects on the environment and in biological health. In this paper, we describe the design and preparation of a colorimetric and ratiometric fluorescence probe for the visual detection of HSO3 - (excitation wavelengths were, respectively, 336 nm and 520 nm). This method showed some advantages including simple preparation, high selectivity, fast response, and significant colour and fluorescence ratio (F450 /F594 ) changes in the presence of HSO3 - . In addition, this probe was used successfully for the detection of HSO3 - in real water samples and showed a good recovery rate range.

A highly selective aggregation-induced emission fluorogen for sensitive detection of Al3+ in living cells.

A Schiff's base derivative was synthesized using a condensation reaction between 8-formyl-7-hydroxy-4-methylcoumarin and furan-2-carbohydrazide that produced marked aggregation-induced emission and had excellent ability to specifically recognize aluminium ions (Al3+ ). This compound displayed faint fluorescence in the benign solvent dimethyl formamide, and exhibited obvious green fluorescence following addition of specific amounts of water. Moreover, it exhibited strong blue fluorescence after combination with Al3+ even in the presence of other interfering ions. These experimental results demonstrated that this derivative could be used as a fluorescence probe for Al3+ . The advantages, including significant fluorescence change, high selectivity and sensitivity, and fast response, meant that this probe could be used both to detect Al3+ in water samples and for fluorescence imaging in living cells.

A fluorescent probe for hypochlorite with colorimetric and fluorometric characteristics and imaging in living cells.

An excellent fluorescent probe with "turn on" phenomenon for sensitive monitoring hypochlorite (ClO-) was prepared using the mild condensation reaction between coumarin and hydroxylamine (NH2OH). The probe possessed potent selectivity to ClO- with obvious color changes from yellow to light yellow and green to blue fluorescence emission, which could be noticed by the naked eye. Moreover, the probe has been succeeded in imaging ClO- in living A549 cells and thus has the potential prospect in the visual detection of intracellular ClO-.

A Colorimetric and Fluorescent Probe Based on Rhodamine B for Detection of Fe3+ and Cu2+ Ions.

Development of optical probe for the detections of Fe3+ and Cu2+ is one of the most active and interesting research directions in analytical chemistry because of their vital roles in the environment protection and human health. Herein, a turn on optical rhodamine B-based probe (probe 1) with the significant changes in color and fluorescence has been prepared. The color of this probe solution changed from colorless to amaranth in the presence of Fe3+ and to pink in the presence of Cu2+, which is promising for the qualitative recognition of Fe3+ and Cu2+. More importantly, probe 1 could be used for the quantitative analysis of Fe3+ and Cu2+ by fluorescence enhancement. The detection limits for Fe3+ and Cu2+ reached 8.1 × 10-8 M and 4.8 × 10-7 M, respectively. Furthermore, it was found that this probe can also be used for fluorescence imaging of Fe3+ and Cu2+ in living cells.

A Smart Fluorescent Probe Based on Salicylaldehyde Schiff's Base with AIE and ESIPT Characteristics for the Detections of N2H4 and ClO.

Smart and versatile salicylaldehyde Schiff's bases have been proved their excellent performances including large shocks shift, dual emission wavelengths and sensitive to environment for fluorescence analysis. Herein, a simple salicylaldehyde Schiff's base molecular (PBAS) with aggregation-induced emission (AIE) and the excited-state intramolecular proton-transfer (ESIPT) effects was constructed for detecting N2H4 and ClO-. The highly specific and sensitive response to N2H4 was witnessed by the fast turn-on of the strong blue fluorescence and to ClO- was observed by the rapid turn off of the weak green fluorescence simultaneous decomposing of the probe. The results of mass spectrum analysis showed that probe PBAS decomposed under the influence of N2H4, whereas probe PBAS can complex with ClO- and prevent effective ESIPT process. Benefiting from its high properties, this fluorescence molecular provides an effective tool for probing N2H4 and ClO- in live cells.

A fluorescence turn-on probe for rapid monitoring of hypochlorite based on coumarin Schiff base.

A simple Schiff base was prepared by mild condensation reaction between a coumarin fluorescent group and diaminomaleonitrile, and it could serve as an excellent fluorescent probe for fast detection of ClO- with high selectivity and sensitivity. Along with addition of ClO-, this probe fleetingly showed noteworthy "turn-on" phenomenon accompanied by an increase of fluorescence intensity and the change of emission color from yellow to blue. This change of fluorescence is so significant that it can be observed by the naked-eye under a handheld ultraviolet light of 365 nm. However, other common reactive oxygen species exhibited no or very little fluorescent response under the same conditions. The limit of detection of this probe toward ClO- had a sensitivity feature as low as 9.6 nM. On account of these excellent features of short response time, remarkable fluorescence and color signal changes, high sensitivity and selectivity, this probe was effectively used for the fluorescence detection of ClO- in water samples. The values of the relative standard deviation were between 1.41% and 2.91%. More importantly, this probe displays excellent imaging capability in cytoplasm as well as very low cell toxicity and was unambiguously applied to image ClO- in living cells. Graphical abstract A fluorescent probe based on coumarin for detection of ClO- was successfully developed, which can besuccessfully used for the detection of ClO- in living cells and in water sample because of the excellentfeatures including short response time, remarkable fluorescence and color signal changes, high sensitivityand selectivity.

A label-free turn-on fluorescence probe for rapidly distinguishing cysteine over glutathione in water solution.

A novel label-free fluorescent chemodosimeter (C1) was synthesized, based on coumarin and N-(4-aminobenzoyl)-ß-alanine, for the selective detection of cysteine (Cys) over glutathione (GSH), which involved a click reaction of Cys to CN of a Schiff base. The probe C1 featured a fast response (about 3 min), emission in the visible region, and high selectivity. Addition of Cys in HEPES-NaOH solution (pH 7.4) to C1 in water resulted in the appearance of a new emission peak at 445 nm, in company with remarkable enhancement of fluorescence intensity, while other amino acids did not induce any significant fluorescence change. Meanwhile, the addition reaction of Cys to C1 elicited 90.8-fold fluorescence intensity enhancement, which resulted in a change of emission color from orange to blue.

Recent Advances in Organic Small-Molecule Fluorescent Probes Based on Dicyanoisophorone Derivatives.

Fluorescent probe technology holds great promise in the fields of environmental monitoring and clinical diagnosis due to its inherent advantages, including easy operation, reliable detection signals, fast analysis speed, and in situ imaging capabilities. In recent years, a wide range of fluorescent probes based on diverse fluorophores have been developed for the analysis and detection of various analytes, yielding significant achievement. Among these fluorophores, the dicyanoisophorone-based fluorophores have garnered significant attention. Dicyanoisoporone exhibits minimal fluorescence, yet possesses a robust electron-withdrawing capability, rendering it suitable for constructing of D-π-A structured fluorophores. Leveraging the intramolecular charge transfer (ICT) effect, such fluorophores exhibit near-infrared (NIR) fluorescence emission with a large Stokes shift, thereby offering remarkable advantages in the design and development of NIR fluorescence probes. This review article primarily focus on small-molecule dicyanoisoporone-based probes from the past two years, elucidating their design strategies, detection performances, and applications. Additionally, we summarize current challenges while predicting future directions to provide valuable references for developing novel and advanced fluorescence probes based on dicyanoisoporone derivatives.

A ratiometric fluorescent probe for selective detection of hypochlorite (ClO-) and gallium (III) (Ga3+) ions in environmental and food samples.

Hypochlorite (ClO-) and gallium (Ⅲ) ions (Ga3+) have extensive applications in various human industries and daily activities. However, their inherent toxicity poses significant risks to environmental preservation and human well-being. Hence, the development of reliable and handy detection tools for ClO- and Ga3+ in the environment and food is crucial. In this study, a ratiometric fluorescent probe was prepared based on benzothiazolaldehyde and pyridine-2-carboxylic acid hydrazide, which exhibited exceptional performance characteristics for the selective detection of ClO- and Ga3+. These features include high specificity, low detection limits (0.28 µM for ClO-, 0.13 µM for Ga3+), mild pH conditions (pH 4-11 for ClO-, pH 6-11 for Ga3+), fast response time (within 30 s), as well as versatile applicability across different matrices such as water, soil, food, and plant samples. Additionally, this probe can be used with a smartphone color recognition app. The probe offers a convenient and effective tool for the detection of ClO- and Ga3+, demonstrating its potential application value in environmental monitoring and food safety.

A versatile fluorescent probe for the ratiometric detection of hydrazine (N2H4) in water, soil, plant, and food samples.

Hydrazine (N2H4) is a crucial chemical raw material extensively utilized in chemical production. However, due to its volatility, water solubility, and high toxicity, both the gaseous form and aqueous solution of N2H4 pose significant environmental risks by causing severe pollution that can adversely impact plants, microorganisms, and human health. Therefore, accurate detection of N2H4 in the environment is imperative for safeguarding public health. In this study, we synthesized a ratiometric fluorescent probe (BCaz-Cy2) based on Carbazole and Hemicyanine groups. This probe exhibits simple synthesis procedure, rapid response time, high sensitivity and selectivity as well as remarkable detection signals. It enables effective detection of N2H4 in various matrices such as water, food, soil and plant samples thereby significantly expanding the scope of applications for N2H4 probes.

A dicyanisophorone-based probe for dual sensing Zn2+ and Cd2+ by near-infrared fluorescence.

Zinc ions (Zn2+) and cadmium ions (Cd2+) are widely present in our production and life, which are closely related to human health and environmental protection. Hence, it is essential to detect their concentrations. Herein, we developed a convenient and reliable small-molecule fluorescent probe based on Schiff base of dicyanisophorone and 2-hydrazinopyridine. This probe can be able to selectively detect Zn2+ and Cd2+, showing the advantages of near-infrared emission (the maximum emission wavelength: 668 nm), good selectivity, high sensitivity (the detection limits: 0.21 µM and 0.31 µM, respectively) and rapid response (15 s). It has excellent potential for rapid testing and visual tracking of Zn2+ and Cd2+ in aqueous solution and living cells.