Phenanthroimidazole-based fluorescence probe for discriminative detecting of hydrazine and bisulfite and its applications in environmental samples

Hydrazine (N2H4) and bisulfite (HSO3-) detection methods are urgently needed due to its harmful to the human health and environment safety. Herein, we reported a dual-response fluorescence probe EPC, which is capable of sequential detection of N2H4 and HSO3- by two different fluorescence signals. The probe EPC itself showed yellow florescence. In presence of N2H4, probe EPC exhibited an obviously fluorescence change (from yellow to green). However, a new addition product came into being after probe EPC mixed with HSO3-, followed with weak yellow emission. More important, probe EPC exhibited excellent fluorescence response properties for N2H4 and HSO3-, such as high sensitivity (0.182 µM for N2H4, 0.093 µM for HSO3-), rapid response (55 s for N2H4, 45 s for HSO3-), excellent selectivity and anti-interference performance. The sensing mechanisms for N2H4 and HSO3- were proved by 1H NMR and MS spectra. Practical applications were studied. EPC based test paper can be utilized for quantitative detecting N2H4 in actual water samples. And, probe EPC has been successfully applied to recognize N2H4 contaminant in soil samples. Moreover, EPC has great potential to be used to detect HSO3- in real food samples.

An Aggregation-Induced Emissive Platinum(II) Metallacycle as the Energy Donor of Rhodols for Ratiometric Detection of Hydrazine

Industry-produced hydrazine (N2H4) is released into the environment, posing a major risk to human health and the ecosystem. Therefore, it is imperative to develop an effective and convenient method for the detection of N2H4. Herein, artificial light-harvesting systems (ALHSs) for N2H4 detection were constructed by applying an aggregation-induced emission-active platinum(II) metallacycle (TPEMc) as the energy donor and rhodols (P1, P2, and P3) as the energy acceptors. The ratiometric fluorescence probes based on ALHSs for N2H4 showed obvious signal amplification and lower limits of detection compared to those of rhodols (P1, P2, P3) alone. The TPEMc-rhodols systems clearly demonstrated a noticeable increase in fluorescence intensity at 550 nm and an obvious fluorescent color shift from cyan to yellow in the presence of N2H4. Fascinatingly, N2H4 could be visually and quantitatively detected in water by the TPEMc-rhodol systems paired with smartphone RGB analysis. Therefore, the combination of platinum(II) metallacycle with rhodols is a promising strategy for simple, sensitive, and visual detection of N2H4.

Development of a ratiometric fluorescent probe based on caffeic acid for hydrazine detection and its applications in water samples and living cells

Hydrazine (N2H4) has been extensively utilized as a highly reactive chemical reagent. However, it is also seriously harmful to human beings and ecosystem. Thus, the development of an efficient detecting method for hydrazine is desirable. Here, caffeic acid was chose as starting material to synthesize a new ratiometric fluorescent probe HPA for detecting hydrazine. This probe possessed the specific recognition ability for hydrazine over other analytes with low detection limit (0.106 µM) and extremely short time (60 s). The sensing mechanism of probe HPA for hydrazine was proved by 1H NMR titration and theoretical calculations. In addition, the probe HPA was loaded on paper strip for rapid quantitative detection of hydrazine with the aid of a software (Image J). The effective detecting performances of probe HPA for hydrazine were verified in environmental water samples as well as in living cells. Thus, HPA has great potential for detection and analysis of hydrazine in health supervision and environmental protection.

A turn-on fluorescent probe for sensing N2H4 in living cells, zebrafishes and plant root with a large turn-on fluorescence signal

Hydrazine (N₂H₄) plays an important role in industrial production, but it is highly toxic, leaking or exposing it will pollute the environment and cause serious harm to human beings. Therefore, it is necessary to use a simple and effective method to detect N₂H₄ in environmental systems and organisms. Herein, a novel water-soluble fluorescent probe based on coumarin fluorophore, 2-(7-(diethylamino)-2-oxo-2H-chromen-3-yl)isoindoline-1,3-dione (C-Z1), is reported. The fluorescence intensity of the probe at 530 nm was enhanced gradually with the addition of N₂H₄, and the maximum enhancement was about 28 times. The probe has good selectivity and sensitivity, the detection limit of hydrazine hydrate is 1.48 × 10^-7 M, and the response mechanism of the probe is proved by theoretical calculation and experiment. C-Z1 has been shown to detect N₂H₄ in a variety of environmental samples, including water, soil, air, cells, zebrafish and plants. In addition, C-Z1 can be made into test strips for easy portability and used for rapid quantitative detection of N₂H₄ in the field by its distinct change in fluorescence color. Thus, C-Z1 has great potential for the analysis and detection of environmental contaminants.

Covalent Organic Frameworks: Recent Progress in Biomedical Applications

Covalent organic frameworks (COFs) are a type of crystalline organic porous material with specific features and interesting structures, including porosity, large surface area, and biocompatibility. These features enable COFs to be considered as excellent candidates for applications in various fields. Recently, COFs have been widely demonstrated as promising materials for biomedical applications because of their excellent physicochemical properties and ultrathin structures. In this review, we cover the recent progress of COF materials for applications in photodynamic therapy, gene delivery, photothermal therapy, drug delivery, bioimaging, biosensing, and combined therapies. Moreover, the critical challenges and further perspectives with regards to COFs for future biology-facing applications are also discussed.

A fluorescent probe based on triphenylamine with AIE and ICT characteristics for hydrazine detection

A fluorescent probe MAM based on triphenylamine scaffold was synthesized. The electron donating group 4-methoxyphenyl and the electron acceptor dicyanoethylene were introduced on the triphenylamine scaffold to form a D-π-A fluorescent probe. The probe MAM exhibited the typical aggregation-induced emission (AIE) and intramolecular charge transfer (ICT) characteristics with the bright orange-red fluorescent emission in high water fraction (f_w ≥ 50%) and negligible emission in low water fraction. The probe MAM could detect hydrazine (N₂H₄) in DMSO-tris-HCl (10 mM, pH7.4, v/v, 3:1) with high selectivity and sensitivity. The specific reaction between MAM and hydrazine and the formation of the hydrazone blocked the ICT process, and the system emitted the cyan fluorescence which could be easily observed by naked eyes. The limit of detection (LOD) was 0.196 μM (6.25 ppb), which is lower than the US Environmental Protection Agency standard (10 ppb). The test strips prepared by the probe MAM could realize the convenient and rapid detection of N₂H₄ solution and vapor. The application of MAM in actual water samples and cells was investigated, and the results showed that MAM could sense N₂H₄ in environmental and biological aspects with potential application prospects.

A smartphone-adaptable chromogenic and fluorogenic sensor for rapid visual detection of toxic hydrazine in the environment

Hydrazine is an essential chemical in industries, but its high toxicity poses great threats to human health and environmental safety. Hence, it is of great significance to monitor the hydrazine in environment. In this work, we presented a chromogenic and fluorogenic dual-mode sensor RA for the detection of hydrazine based on nucleophilic substitution reaction. A linear relationship was obtained between the fluorescence intensity and the concentrations of N₂H₄ ranging from 0 to 35 μM (R² = 0.9936). The sensor can determine hydrazine with fast response (within 12 min), low limit of detection (0.129 μM) and high selectivity. RA was successfully used to detect N₂H₄ in real water samples with good recoveries and the results corresponded to the standard method. Furthermore, the sensor-coated portable test papers were fabricated, which can visually quantify hydrazine solutions with obvious fluorescence transformation from colorless to red. Moreover, RA-loaded papers were used to create a smartphone-adaptable RGB values analytical method for quantitative N₂H₄ detection.

A novel colorimetric fluorescent probe for detecting hydrazine in living cells and zebrafish

Hydrazine (NH₂ NH₂ ) is a highly toxic organic substance that poses threat to human health. Monitoring hydrazine with high sensitivity and selectivity is very important. Herein, a simple colorimetric fluorescent probe for hydrazine detection, which is a seminaphthorhodafluor derivative containing thiophene-2-carboxylic acid ester reaction site, was rationally constructed. The probe itself exhibits weak fluorescence. The fluorescence is significantly enhanced when hydrazine is added. The probe exhibited a broad linear range (0-1 mM) with satisfactory selectivity and sensitivity (LOD 36.4 nM), which turns out to be an excellent fluorescent probe for monitoring hydrazine. Additionally, the probe was used to track hydrazine in living cells and zebrafish with great success, and the detection performance was satisfying. These results proved that this type of fluorescent probe with the thiophene-2-carboxylic acid ester structure can detect hydrazine with higher selectivity and sensitivity.

The preparation of a special fluorescent probe with an aggregation-induced emission effect for detecting hydrazine in water

A novel phenyl-carbazole fluorescent molecule, PCBI, with an AIE effect is used as an excellent special probe for the detection of N2H4 in a DMF–H2O system.

A practical pH-compatible fluorescent sensor for hydrazine in soil, water and living cells

The excellent water solubility of hydrazine (N₂H₄) allows it to easily invade the human body through the skin and respiratory tract, thereby damaging human organs and the central nervous system. To realize the monitoring of N₂H₄ effectively, first, coumarin was used to construct an inner alicyclic ring as the reaction site, extending the conjugation and strengthening the rigidity of the probe Co-Hy to improve its luminescence performance and enhance its ability to resist acids and alkalis. Second, we introduced a carboxyl group at the ortho position of the inner alicyclic ring to improve the water solubility of Co-Hy, and its strong electron pulling effect increased the activity of the reaction site. Spectroscopy experiments showed that Co-Hy featured excellent water solubility, high pH resistance (pH 4-11), excellent selectivity, fast analysis speed (within 5 minutes), and a low detection limit toward N₂H₄ (69 nM, 2.2 ppb). In addition, test-strip, spray, and cell-imaging experiments confirmed the outstanding application potential of Co-Hy for convenient N₂H₄ analysis in a variety of environments.