A naked-eye visible colorimetric and fluorescent chemosensor for rapid detection of fluoride anions: Implication for toxic fluorine-containing pesticides detection

A novel fluorescent probe for efficient detection of fluoride ions in living animal and plant tissues

This work presents the design and synthesis of a new fluorescent probe IF-Br-F for the specific detection of fluoride ions. The IF-Br-F probe has excellent fluorescence properties, and the mechanism of the probe response to fluoride ions was successfully verified via HRMS and DFT calculations. IF-Br-F has high sensitivity and low detection limit (5.82 × 10-7 mol L-1) and successfully detects fluoride ions in actual water samples. The probe can be applied to fluorescence imaging of zebrafish, cells, and Arabidopsis roots and exhibits low cytotoxicity and good biocompatibility.

A V-shaped bis-coumarin based fluorescence probe for F- detection in tea infusions and potable water and bioimaging applications in living systems

Fluorine (F) is a pivotal element in the formation of human dental and skeletal tissues, and the consumption of water and tea constitutes a significant source of fluoride intake. However, prolonged ingestion of water and tea with excessive fluoride content can lead to fluorosis, which poses a serious health hazard. In this manuscript, a novel turn-on fluorescent probe DCF synthesized by bis-coumarin and tert-butyldiphenylsilane (TBDPS) was introduced for detecting F- in potable water and tea infusions. By leveraging the unique chemical affinity between fluoride and silicon, F- triggers the silicon-oxygen bond cleavage in DCF, culminating in a conspicuous emission of yellow fluorescence. Validated through a succession of optical tests, this probe exhibits remarkable advantages in terms of superior selectivity, a low detection limit, a large Stokes shift, and robust interference resistance when detecting inorganic fluoride. Moreover, it can serve as portable test strips for on-site real-time identification and quantitative analysis of F-. Furthermore, the application of DCF for in-situ monitoring and imaging of F- in zebrafish and soybean root tissues proved its significant value for F- detection in both animal and plant systems. This probe potentially functions as an efficient instrument for delving into the toxic mechanisms of fluoride in physiological processes.

A Chromogenic Probe for Detection of Biologically Important Anions and its Implications for Designing Molecular Logic Gates

Detection of fluoride (F-), acetate (AcO-), and cyanide (CN-) anions is vital from the biological and environmental aspects. In the present contributions, we have introduced a simple Salen-type chromogenic sensor, BEN, to detect these biologically important anions. Changes in UV-visible absorption spectra and color of BEN solution from very pale yellow to pink color are similar for each of these anions and found to be reversible only in the case of F- ions in attendance of HSO4- ions. The estimated limit of detection of BEN solution for detecting F-, AcO-, and CN- anions is found to be below the micromolar (μM) concentration level. Our fabricated handy paper test kit is suitable for qualitatively naked-eye detection of the anions. An immediate quantitative estimation of these important anions is possible using our BEN employing a smartphone, avoiding any costly experimental setup.

Spectroscopic and Biological Properties of the 3-Imino-1,8-naphthalimide Derivatives as Fluorophores for Cellular Imaging

This paper presents the photophysical and biological properties of eight 3-imino-1,8-naphthalimides. The optical properties of the compounds were investigated in the solvents that differed in their polarity (dichloromethane, acetonitrile, and methanol), including three methods of sample preparation using different pre-dissolving solvents such as dimethyl sulfoxide or chloroform. In the course of the research, it was found that there are strong interactions between the tested compounds and DMSO, which was visible as a change in the maximum emission band (λem) of the neat 3-imino-1,8-naphthalimides (λem = 470-480 nm) and between the compounds and DMSO (λem = 504-514 nm). The shift of the emission maximum that was associated with the presence of a small amount of DMSO in the sample was as much as 41 nm. In addition, the susceptibility of imines to hydrolysis in the methanol/water mixture with increasing water content and in the methanol/water mixture (v/v; 1:1) in the pH range from 1 to 12 was discussed. The studies showed that the compounds are hydrolysed in the CH3OH/H2O system in an acidic environment (pH in the range of 1 to 4). In addition, it was found that partial hydrolysis occurs in systems with an increased amount of water, and its degree may depend on the type of substituent on the imine bond. The compounds tended to quench the emission (ACQ) in the aggregated state and increase the emission related to the protonation of the imine bond. Moreover, it was found that the substituent in the imine bonds influenced a compound's individual photophysical properties. Biological tests, including cytotoxicity studies and cellular localisation, were also performed for all of the molecules. All of the tested compounds exhibited green fluorescence in the MCF-7 cells and showed co-localisation in the mitochondria, endoplasmic reticulum, and lysosome. The obtained photophysical and biological results indicate the promising potential use of the tested compounds as cellular dyes.

Sensitive fluorescence assay for the detection of glyphosate with NACCu2+ complex

Glyphosate is widely used as an herbicide in weed control. However, the excessive use and residue of glyphosate adversely affect the environment. Thus, a rapid and highly sensitive system must be developed for glyphosate detection. Herein, a novel turn-on fluorescent probe was designed and synthesized for glyphosate, that is N-butyl-1,8-naphthalimide-4-hydrazino-6-isopropyl-chromone (NAC). The fluorescence of NAC was quenched by the addition of Cu²⁺ to form NACCu²⁺ complex in dimethyl sulfoxide/2-[4-(2-hydroxyethyl)piperazin-1-yl]ethanesulfonic acid (DMSO/HEPES, 9/1, v/v, pH = 7.0). Upon the addition of glyphosate, the fluorescence of NACCu²⁺ was recovered through chelation between Cu²⁺ and glyphosate. The NACCu²⁺ complex exhibited the desired linearity of glyphosate concentration under optimum conditions in the range of 0-40 μM with a low detection limit of 36 nM. Based on competitive coordination, NACCu²⁺ exhibited good sensitivity and selectivity for glyphosate. Moreover, NAC was successfully utilized to detect glyphosate in tap water, local water from Songhua River, soil, maize, and soybean with convenient operations, indicating a promising application in pesticide residue detection.

A coumarin based Schiff Base: An effective colorimetric sensor for selective detection of F- ion in real samples and DFT studies

Chemosensors are molecular devices which react with target and give a visible signal, which is a degree of its sensitivity. Herein, a novel coumarin based Schiff Base has been synthesized for F^- ions detection. The chemosensor showed an intense color change upon the addition of F^- ions (light yellow to purple). The chemosensor has fewer effects of competing anions. The limit of detection is calculated as low as 1.1 × 10^-6 and the binding constant was determined as 1.61 × 10⁴. The job's plot confirmed 1:1 stoichiometry between chemosensor and F^- ion. The reverse reaction of chemosensor with MeOH is useful to construct a combinatorial logic circuit gates. The interaction mechanism of chemosensor was deliberated by ¹H NMR, FTIR, and DFT studies. Finally, the chemosensor was useful to detect F^- ions in tooth-paste sample and test strip is prepared for F^- ions detection.

A scientometric study on application of electrochemical sensors for detection of pesticide using graphene-based electrode modifiers

Pesticide testing is an important topic in environmental protection and food safety. The development of green, accurate and reliable pesticide residue detection methods is an important technical support for implementing of agricultural quality supervision. Electrochemical sensors are a very promising analytical method for pesticide detection due to their high sensitivity, speed, low cost and portability. Performance enhancement of electrochemical sensors is often accompanied by research advances in materials science. Among them, carbon material is a very important electrode material for the fabrication of electrochemical sensors. The discovery of graphene makes it the most promising candidate among carbon materials for sensor performance enhancement. The topic of this review is the use of graphene-modified electrochemical sensors for pesticide detection in the last decade. Traditional literature summaries and bibliometric analyses were used for an in-depth analysis of this topic. In addition to the introduction of different sensor types and performance comparisons, this review also parses the authors' country, keywords and publication frequency. The related research experienced rapid growth several years ago and has now reached a relatively stable stage. We also discuss the perspectives on this topic.

A Significant Fluorescence Turn-On Probe for the Recognition of Al3+ and Its Application

An easy prepared probe, BHMMP, was designed and synthesized, which displayed a significant fluorescence enhancement (over 38-fold) and obvious color change in the recognition of Al³⁺. The binding ratio of probe BHMMP to Al³⁺ was determined as 1:1, according to Job plot. The binding mechanism was fully clarified by the experiments, such as FT-IR spectrum, ESI-MS analysis, and ¹H NMR titration. A DFT study further confirmed the binding mode of BHMMP to Al³⁺. The limit of detection (LOD) for Al³⁺ was determined as low as 0.70 µM, based on the fluorescence titration of BHMMP. Moreover, the results from real sample experiments, including real water samples, test papers, and cell images, well-demonstrated that BHMMP was capable of sensing Al³⁺ in environmental and biological systems.

Non-biological fluorescent chemosensors for pesticides detection

The ongoing poisoning of agricultural products has pushed the security problem to become an important issue. Among them, exceeding the standard rate of pesticide residues is the main factor influencing the quality and security of agricultural products. Moreover, the abuse of pesticides has introduced a large amount of residues in soil and drinking water, which will enter the food chain to the human body, leading to neurological disorders and cancer. Therefore, great efforts have been devoted to developing fluorescent sensors for detecting pesticide in a facile, quickly, sensitive, selective, accurate manner, which exhibit greater advantages than some traditional methods. In this review, we mainly focus on summarizing the non-biological fluorescent probes for organic pesticides detection with the detection limit of micromole to nanomole, including organic functional small molecules, calixarenes and pillararenes, metal organic framework systems, and nanomaterials. Meanwhile, we described the different sensing mechanisms for pesticides detection of these mentioned fluorescent sensors, the detection limit of each pesticide, the application in detecting actual samples, as well as their respective advantages and development prospects associated with present non-biological fluorescent sensors.

A simple and rapid fluorescent approach for Pb2+ determination and application in water samples and living cells

A novel selective fluorescent chemosensor, thiosemicarbazide-appended naphthalimide derivative (TND), has been designed and synthesized, which exhibited good selectivity and sensibility for Pb²⁺ in CH₃CN:H₂O (1:1) solution. The probe TND showed obvious color changes under UV light of 365 nm and displayed turn-on fluorescence response with Pb²⁺ added. The binding mode of TND with Pb²⁺ was found to be 1:1 based on the Job's plot analysis. The detection limit of Pb²⁺ was 4.7 nM, which is far below the allowable concentration determined by WHO in drinking water. Moreover, the fortified recoveries of Pb²⁺ were from 100.54% to 113.68% in water samples. TND is also applied for fluorescence imaging of Pb²⁺ in lysosomes of human stromal cell line (HSC). This study indicated that TND would be a potential sensor detecting Pb²⁺ in real sample.

Fabrication of stable electrospun blended chitosan-poly(vinyl alcohol) nanofibers for designing naked-eye colorimetric glucose biosensor based on GOx/HRP

In this study, designing of a stable electrospun blended chitosan (CS)-poly(vinyl alcohol) (PVA) nanofibers for colorimetric glucose biosensing in an aqueous medium was investigated. CS and PVA solutions were blended to acquire an optimum content (CS/PVA:1/4) and electrospunned to obtain uniform and bead-free CS/PVA nanofiber structures following the optimization of the electrospinning parameters (33 kV, 20 cm, and 1.2 ml.h^-1). Crosslinking process applied subsequently provided mechanically and chemically stable nanofibers with an average diameter of 378 nm. The morphological homogeneity, high fluid absorption ability (>%50), thermal (<230 °C) and morphological stability, surface hydrophilicity and degrability properties of cross-linked CS/PVA nanofiber demonstrated their great potential to be developed as an eye-readable strip for biosensing applications. The glucose oxidase (GOx) and horseradish peroxidase (HRP) was immobilized by physical adsorption on the cross-linked CS/PVA nanofiber. The glucose assay analysis by ultraviolet-visible (UV-Vis) spectrophotometry using the same enzymatic system of the proposed glucose strips in form of absorbance versus concentration plot was found to be linear over a glucose concentration range of 2.7 to 13.8 mM. The prepared naked eye colorimetric glucose detection strips, with lower detection limit of 2.7 mM, demonstrated dramatic color change from white (0 mM) to brownish-orange (13.8 mM). The developed cross-linked CS/PVA nanofiber strips, prepared by electrospinnig procedure, could be easily adapted to a color map, as an alternative material for glucose sensing. Design of a practical, low-cost, and environmental-friendly bio-based CS/PVA testing strips for eye readable detection were presented and suggested as an applicable medium for a wide range of glucose concentrations.

New Fluorescent Probes for the Sensitive Determination of Glyphosate in Food and Environmental Samples

In this paper, a dual-functional probe, 2-(benzothiazol)-4-(3-hydroxy-4-methylphenyl) imino phenol (BHMH), was synthesized and characterized for the simultaneous detection of Cu2+ and Fe3+ in dimethyl sulfoxide/4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (DMSO/HEPES) (1:4, v/v, pH = 6.0). The limits of detections (LODs) for Cu2+ and Fe3+ were 9.05 and 48 nM, respectively. Based on the competitive coordination, the complex BHMH-Cu2+/Fe3+ exhibited good sensitivity and selectivity for glyphosate. The LODs of BHMH-Cu2+ and BHMH-Fe3+ for glyphosate were 0.41 and 0.63 μM, respectively. The probe quantitatively detected glyphosate in tap water, Songhua River water, local water and soil, and food samples. The colorimetric on-site glyphosate sensing through the probe BHMH-Cu2+ was also studied based on smartphones. BHMH and BHMH-Cu2+/Fe3+ exhibited outstanding imaging capabilities for Cu2+, Fe3+, and glyphosate in living cells with low cytotoxicity, especially the first time for glyphosate.

Tetraphenylethylene-Substituted Bis(thienyl)imidazole (DTITPE), An Efficient Molecular Sensor for the Detection and Quantification of Fluoride Ions

Fluoride ion plays a pivotal role in a range of biological and chemical applications however excessive exposure can cause severe kidney and gastric problems. A simple and selective molecular sensor, 4,5-di(thien-2-yl)-2-(4-(1,2,2-triphenylvinyl)-phenyl)-1H-imidazole, DTITPE, has been synthesized for the detection of fluoride ions, with detection limits of 1.37 × 10−7 M and 2.67 × 10−13 M, determined by UV-vis. and fluorescence spectroscopy, respectively. The variation in the optical properties of the molecular sensor in the presence of fluoride ions was explained by an intermolecular charge transfer (ICT) process between the bis(thienyl) and tetraphenylethylene (TPE) moieties upon the formation of a N-H---F− hydrogen bond of the imidazole proton. The sensing mechanism exhibited by DTITPE for fluoride ions was confirmed by 1H NMR spectroscopic studies and density functional theory (DFT) calculations. Test strips coated with the molecular sensor can detect fluoride ions in THF, undergoing a color change from white to yellow, which can be observed with the naked eye, showcasing their potential real-world application.

NPA-Cu2+ Complex as a Fluorescent Sensing Platform for the Selective and Sensitive Detection of Glyphosate

Glyphosate is a highly effective, low-toxicity, broad-spectrum herbicide, which is extensively used in global agriculture to control weeds and vegetation. However, glyphosate has become a potential threat to human and ecosystem because of its excessive usage and its bio-concentration in soil and water. Herein, a novel turn-on fluorescent probe, N-n-butyl-4-(3-pyridin)ylmethylidenehydrazine-1,8-naphthalimide (NPA), is proposed. It efficiently detected Cu2+ within the limit of detection (LOD) of 0.21 μM and displayed a dramatic turn-off fluorescence response in CH3CN. NPA-Cu2+ complex was employed to selectively and sensitively monitor glyphosate concentrations in real samples accompanied by a fluorescence turn-on mode. A good linear relationship between NPA and Cu2+ of glyphosate was found in the range of 10-100 μM with an LOD of 1.87 μM. Glyphosate exhibited a stronger chelation with Cu2+ than NPA and the system released free NPA through competitive coordination. The proposed method demonstrates great potential in quantitatively detecting glyphosate in tap water, local water from Songhua River, soil, rice, millet, maize, soybean, mung bean, and milk with mild conditions, and is a simple procedure with obvious consequences and no need for large instruments or pretreatment.

Hydrogen-Bonded Colorimetric and Fluorescence Chemosensor for Fluoride Anion With High Selectivity and Sensitivity: A Review

In recent years, the wide application of fluoride materials has grown rapidly, therefore excessive discharge in the surrounding environment, especially in drinking water and organic effluent, has become a potential hazard to humans, and has even resulted in fluorosis disease. The development of a highly effective and convenient method to recognize fluoride anions in surrounding environments seems necessary and urgent. Among which, the development of a colorimetric and fluorescence fluoride chemosensor with obvious color changing allowing for naked-eye detection with high sensitivity and selectivity is more interesting and challenging. In this minireview, current novel colorimetric and fluorescence chemosensors for fluoride anions by hydrogen-bond interaction are introduced, including obvious color changing by naked-eye detection, high sensitivity and selectivity, non-pollution and fluoride extraction ability, aqueous detection, and other additional functions. Finally, the perspective of the fluoride chemosensor design concept and potential evolution trends are pointed out.

Perfluoro octanoic acid-modified magnetic hyperbranched polyamideamine as a sorbent for the extraction of fluorine-containing pesticides from water samples

Perfluoro octanoic acid was modified on the surface of magnetic hyperbranched polyamideamine by acid amine condensation. The morphology and chemical composition of perfluoro octanoic acid-modified magnetic hyperbranched polyamideamine was characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, zeta potential, particle size analysis, Brunauer-Emmett-Teller measurement, and X-ray photoelectron spectroscopy. Perfluoro octanoic acid-modified magnetic hyperbranched polyamideamine was applied in magnetic solid phase extraction for the separation and enrichment of four fluorine-containing pesticides (indoxacarb, metaflumizone, cyflumetofen, and cyhalothrin). The magnetic solid phase extraction method based on perfluoro octanoic acid-modified magnetic hyperbranched polyamideamine has low method detection limits (0.30-0.49 μg/L), a satisfactory coefficient of determination (0.9995-0.9999), wide linear ranges (2.5-250 μg/L), and good repeatability (intraday: 2.6-4.7%; interday: 1.1-7.9%). The enrichment factors and extraction efficiences varied from 55 to 76 and 69 to 96%, respectively. The sorbent-to-sorbent reproducibility was in the range of 3.2-7.6%, indicating that the synthesis of the sorbent was reliable. For the detection of actual water samples, the relative recoveries were in the range from 80.1 to 114.4% with relative standard deviations less than 9.6%. The calculation results of quantum chemistry calculations showed that after the modification of perfluoro octanoic acid, the interaction between the sorbent and four fluorine-containing pesticides was stronger.

A New Reversible Colorimetric Chemosensor Based on Julolidine Moiety for Detecting F. J Fluoresc 2021;31:1675-1682. [PMID: 34387807 DOI: 10.1007/s10895-021-02801-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

We synthesized an original reversible colorimetric chemosensor PDJ ((E)-9-((2-(6-chloropyridazin-3-yl)hydrazono)methyl)-2,3,6,7-tetrahydro-1H,5H-pyrido[3,2,1-ij]quinolin-8-ol) for the detection of F^-. PDJ displayed a selective colorimetric detection to F^- with a variation of color from colorless to yellow. Limit of detection of PDJ for F^- was calculated as 12.1 µM. The binding mode of PDJ and F^- turned out to be a 1:1 ratio using Job plot. Sensing process of F^- by PDJ was demonstrated by ¹H NMR titration and DFT calculation studies that suggested hydrogen bond interactions followed by deprotonation. Moreover, the practicality of PDJ was demonstrated via a reversible test with TFA (trifluoroacetic acid).

Extraction and electrochemical sensing of pesticides in food and environmental samples by use of polydopamine-based materials

Polydopamine has high adsorption capacities for pollutants such as pesticides in food and environmental matrices. Consequently, it has found applications in some sorbent-based micro-extraction techniques such as solid phase micro-extraction and magnetic solid phase extraction. This paper gives a detailed review of the application of polydopamine-based adsorbents for the extraction of pesticides in food and environmental matrices using these techniques. The adhesive properties of polydopamine have made it to be a suitable material for the immobilisation of the components of electrochemical sensors used to detect pesticides in food and environmental matrices. This paper also gives a comprehensive review on the application of polydopamine in electrochemical sensors such as acetylcholinesterase sensors, molecularly imprinted sensors and aptasensors. The use of polydopamine-based adsorbents during the extraction and electrochemical sensing of pesticides in food and environmental matrices is not free of challenges. In this review, the challenges encountered during the use of polydopamine-based adsorbents are also discussed.

A dual thiourea-appended perylenebisimide "turn-on" fluorescent chemosensor with high selectivity and sensitivity for Hg2+ in living cells

Sensing heavy metal ions particularly for the most toxic Hg²⁺ is a long-term pursuit for chemists because of its obvious and extreme harmfulness to both the environment and human health. Herein, a novel 'turn-on' perylenebisimide-thiourea fluorescent probe PBI-BTB is achieved for rapid detection of Hg²⁺ in a DMSO/H₂O (5/1, v/v) solution through a typical Hg²⁺-promoting desulfurization reaction, which has been investigated through Job's plot titration, FT-IR, ¹H NMR and HRMS analysis. A remarkable fluorescence emission enhancement at 540 and 580 nm is observed in the presence of Hg²⁺, which is visible to the naked eye with high selectivity and sensitivity. Moreover, probe PBI-BTB combined strong anti-interference recognition with short response time (< 1 min). The rapid fluorescence response with low limit of detection (0.35 μM) in a wide pH range of 3.0-11.0 makes PBI-BTB a promising candidate for detection of Hg²⁺ without any buffer system. Furthermore, the practicability of probe PBI-BTB upon the Hg²⁺ recognition in human liver cancer cells (HepG-2) has been studied through fluorescent live cell imaging which reveals the probe's low toxicity to organism as well as the favorable cell permeability of PBI-BTB for detecting Hg²⁺ in biological systems.

Two Novel Fluorescent Probes as Systematic Sensors for Multiple Metal Ions: Focus on Detection of Hg2

Many precedents prove that fluorescent probes are promising candidates for detection of metal ions in the environment and biological systems. Herein, two novel photoinduced electron transfer (PET)-based fluorescent probes, CH 3 -R6G and CN-R6G, were rationally synthesized by incorporating a triazolyl benzaldehyde moiety into the rhodamine 6G fluorophore. The optical properties of these probes were studied using an ultraviolet-visible (UV-vis) absorption spectrophotometer and a fluorescence spectrophotometer. Through the analysis of the test results, it is concluded that the selectivity and sensitivity of these two probes to Hg2+ are better than to other metal ions (Ag+, Al3+, Ba2+, Cd2+, Co3+, Cu2+, Cr3+, Fe3+, Ga2+, K+, Mg2+, Na+, Ni2+, Pb2+, and Zn2+). According to the standard curve diagram, the detection limits of CH 3 -R6G and CN-R6G were determined to be 1.34 × 10-8 and 1.56 × 10-8 M, respectively. Reaction of the probes with Hg2+ resulted in a color change of the solution from colorless to pink. The corresponding molecular geometric configuration, orbital electron distribution, and orbital energy of these two compounds were predicted by density functional theory (DFT). The two probes CH 3 -R6G and CN-R6G have been successfully used for imaging Hg2+ in live breast cancer cells, thereby indicating their great potential for the micro-detection of Hg2+ in vivo.

A Highly Selective Perylenediimide-Based Chemosensor: "Naked-Eye" Colorimetric and Fluorescent Turn-On Recognition for Al3

A novel “turn-on” fluorescent probe (PCN) was designed, synthesized, and characterized with perylene tetracarboxylic disimide as the fluorophore and Schiff base subunit as the metal ion receptor. The probe demonstrated a considerable fluorescence enhancement in the presence of Al³⁺ in DMF with high selectivity and sensitivity. Furthermore, the considerably “off–on” fluorescence response simultaneously led to the apparent color change from colorless to brilliant yellow, which could also be identified by naked eye easily. The sensing capability of PCN to Al³⁺ was evaluated by the changes in ultraviolet–visible, fluorescence, Fourier transform–infrared, proton nuclear magnetic resonance, and high-resolution mass spectrometry spectroscopies. The linear concentration range for Al³⁺ was 0–63 μM with a detection limit of 0.16 μM, which allowed for the quantitative determination of Al³⁺.