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In this work, L-Histidine-protected copper nanoclusters synthesized by changing the pH levels of precursor solution have been shown to display different emission wavelengths and intensities. As determined by mass spectrometry, nanoclusters Cu3L2 synthesized at acidic pH have 3 atoms in their core and emit in the greenish-yellow region, and nanoclusters Cu2L2, synthesized in the basic conditions have 2 atoms in their core and emit in the blue-green region. They are expected to have coordination through the carboxylate group and nitrogen of the imidazole ring of histidine ligand, respectively. Metal ions Mg2+, Mn2+, Zn2+, and Pb2+ selectively enhance the interaction between carboxylate – copper metal core and increase the emission intensity of Cu3L2. These metal ions weaken the interaction between imidazole nitrogen and copper metal core and quench the emission intensity of Cu2L2. As synthesized, nanoclusters exhibit good water solubility and photostability, they can act as fluorescent probes to sense the metal ions, therefore, they were utilized for the optical sensing of the mentioned metal ions. Fluorescent nanoclusters were found to sense even a very low concentration of metal ions with a limit of detection (3 σ/slope) in nanomolar range. [ABSTRACT FROM AUTHOR]

This paper scrutinises the development of low-cost hypersensitive fluorescent probes manipulated chemically with Schiff base complexes and their prospective applicability for the detection of nitro explosives in light of the rapidly expanding demand for anti-trafficking measures. In this study, a new Zn(II) metal complex has been synthesized in one pot using the Schiff base ligand L= 2-methoxy-5-methyl-N-(2-pyridin-2-ylmethylene) aniline. The complex was also thoroughly characterised using various spectroscopic tools and subjected to single crystal XRD analysis. In the asymmetric unit, square pyramidal zinc (II) centre exist in the inner N2O compartment of the ligand L. The intermolecular Cg···Cg interactions exist between two different asymmetric residual units lead to supramolecular assembly along b axis. By turning off the fluorescence response, the complex serves as a sensor for the detection of nitro aromatics in CH3CN solution. A significant quenching efficiency has been reported with a quenching constant (KSV) 1.8 × 104 M-1 for 4-nitrobenzoic acid during investigation of sensing phenomenon in solution phase. In addition, determining the binding stoichiometry of the chemosensor with NO2 and the binding constant, the mechanism of fluorescence quenching has also been postulated. The detection limit of NO2 is 7.6×10 -7 M, with the binding constant k = 1.1021× 108 M-1. Additionally, the DFT calculation makes it easier to comprehend the appropriate binding process in light of the findings of experiments. We also designed a paper sensor strip for the visual detection of Nitro Explosive Residues in light of the sensor's potential used in forensic investigations. [ABSTRACT FROM AUTHOR]

A novel flavonol-based fluorescent probe, Fla-DNT, has been synthesized for the rapid and specific detection of H2S. Fla-DNT exhibits excellent selectivity and anti-interference properties, a short response time (4 min), large Stokes shift (138 nm), and low detection limit (1.357 µM). Upon exposure to H2S, Fla-DNT displays a remarkable increase in fluorescence intensity at 542 nm. Meanwhile, the recognizing site of H2S was predicted through Electrostatic potential and ADCH charges calculations, while the sensing mechanism of H2S was determined via HRMS analysis and DFT calculation. More importantly, the probe owes multiple applications, such as a recovery rate ranging from 92.00 to 102.10% for detecting H2S in water samples, and it can be fabricated into fluorescent strips to track H2S production during food spoilage by tracking color changes, thereby enabling real-time monitoring of food freshness. The bioimaging experiments demonstrate the capability of Fla-DNT to detect both endogenous and exogenous H2S in living cells. These results provide a reliable method and idea for H2S detection in complex environments. [ABSTRACT FROM AUTHOR]

Oxidative stress is a trigger for many diseases and occurs with the unstable hypochlorite (ClO−), known as one of the reactive oxygen species (ROS) in organisms. Then, HOCI is acknowledged as an oxidizing species that eliminates a variety of environmental pollutants. Hence, the development of novel methodologies for the selective and precise identification of HOCl/ ClO− is considered to be of utmost importance. In this study, the design, characterization, and applications of a fluorene-based fluorescent probe (FHBP) dependent on the ESIPT mechanism with a "turn-on" response for the sensitive/selective determination of ClO− against other competing samples were reported. The experimental results indicated that the detection limit for ClO−could be quantitatively determined by the probe to be 8.2 × 10−7 M. The binding constant of the probe FHBP with ClO− was computed as 9.75 × 103 M−1. In addition, the response time of FHBP was appointed to be 30 s, indicating a rapid reaction with ClO−. It has also been demonstrated that this probe can be successfully used for the detection of ClO− on filter papers, TLC sheets, cotton swabs, and real samples. [ABSTRACT FROM AUTHOR]

A novel 8-hydroxy quinoline-derived amide receptor, in conjunction with its Cu (II) and Zn (II) complexes, has been strategically developed to function as remarkably efficient fluorescent receptors with a distinct capability for anion sensing. The comprehensive characterization of the synthesized compounds were achieved through UV-Vis, IR, NMR, and HRMS spectroscopic techniques. Among the Cu (II) and Zn (II) complexes, the latter exhibits superior selectivity for anions, specifically dihydrogen phosphate and hydrogen sulfate, as their tetrabutylammonium salts in a 9:1 acetonitrile-water (v/v) mixture. The Cu (II) complex demonstrates enhanced anion binding compared to the amide ligand, albeit with reduced selectivity. Furthermore, the affinity was evaluated using the Benesi-Hildebrand plot. The binding constants and Limit of Detection (LOD) for both complexes were precisely quantified. The Job plot illustrates a clear 1:1 binding interaction between the metal complexes and the guest anions. Significantly, both metal-complex receptors display a broad spectrum of antibacterial activity, against both gram-positive and gram-negative bacteria. It is worth highlighting that the Zn (II) complexed receptor outperforms the Cu (II) complexed receptor, as evidenced by its considerably lower Minimum Inhibitory Concentration (MIC) value against both bacterial strains. [ABSTRACT FROM AUTHOR]

2-Pyrazoline containing benzothiazole ring 2-[1-(1,3-benzothiazol-2-yl)-5-(4-methoxyphenyl)-4,5-dihydro-1H-pyrazol-3-yl]phenol (BP) have been synthesized for the effective identification of picric acid over other competing nitro compounds using fluorescence technique. The pyrazoline BP showed quenching efficiency as high as 82% comparative to other nitro aromatics. The limit of detection and limit of quantification were found to be 1.1 μM and 3.3 μM. The possible mechanism with the quenched PA detection efficiency was based on fluorescence energy transfer and photoinduced electron transfer. Moreover, the observed results were supported by the optimized structures of the compounds using the DFT/B3LYP/6-311G/LanL2DZ method. Eventually, the pyrazoline derivative BP was further utilized for natural water samples, showing recoveries in the 87.62–101.09% and RSD was less than 3%. [ABSTRACT FROM AUTHOR]

A simple and low-cost green preparation method was used for BSA capped silver nanoclusters (BSA-Ag NCs) as turn on fluorescent probe for glucose. Non-enzymatic fast glucose detection assay with a widest concentration range was proposed which requires neither nanoclusters (NCs) modification nor complicated enzyme immobilization. The DLS analysis, HRTEM patterns, fluorescence and UV-visible measurement well supported the synthesis product. The advantages of the fabricated glucose sensor based on fluorescence increasing of probe compared to other established optical techniques was inspected and summarized as well. The glucose sensor exhibited a high sensitivity, fast response time (in seconds), satisfactory selectivity, well stability (at least two months), low detection limit (31 µmol L− 1) and a wide concentration response (three orders of magnitudes) to glucose between 0.1 and 92 mmol L− 1 as calibration plot. A theoretical model of the sensing mechanism based on the binding interaction of glucose to BSA-Ag NCs is proposed and data fitting demonstrated a good agreement between the experimental and theoretically calculated fluorescence data. The facile preparation and excellent sensing performance of BSA-Ag NCs in the real samples (plasma and juice) make sure that synthesized probe material is a promising candidate for advanced enzyme-free glucose sensing approach. [ABSTRACT FROM AUTHOR]

Carbon monoxide (CO) is one of the signaling molecules that are ubiquitous in humans, which involves in the regulation of human physiology and pathology. In this work, the probe PEC was designed and synthesized based on BODIPY fluorophore that can selectively detect CO through reducing the nitro group to amino group, resulting in a "turn-on" fluorescence response with a simultaneous increase in the concentration of CO. The response is selective over a variety of relevant reactive free radicals, ions, and amino acid species. PEC has the advantages of good stability, good water solubility, and obvious changes in fluorescence signals. In addition, PEC can be used to detect and track endogenous CO in living cells. [ABSTRACT FROM AUTHOR]

Fe3+ ion plays a very active role in life, agriculture, and industry. Human health and the environment are seriously affected by the abnormal presence or excess of this cation. Therefore, the development of a fast, reliable, sensitive, and simple fluorescent probe to detect this cation is crucial. In the present paper, polycaprolactone-capped zinc oxide quantum dots were prepared for the determination of Fe3+ ions. The proposed fluorescent chemosensor exhibited a fluorometric and strong quenching effect toward Fe3+ ions at two wavelengths (303 and 602 nm). The limit of detection (LOD) was calculated as 0.410, and 0.333µM at the mentioned wavelengths. Also, the binding stoichiometric ratio was calculated as 1:1 by Job's plot. The findings indicated that the PCL@ZnO colorimetric chemosensor could be successfully applied with reliable, and good accuracy for the detection of Fe3+ ions in real seawater samples. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

A new phenanthroimidazole-based fluorescence probe for selective detection of HClO was synthesized and characterized using 1HNMR, 13CNMR, IR, and HRMS. With benzenesulfonohydrazide as the identification group, the probe demonstrated a fast fluorescence response from yellow-green to blue when the HC = N double bond was oxidized and broken into an aldehyde group by HClO. The probe showed high selectivity and sensitivity towards HClO with approximately 4.5-fold fluorescence enhancement and has been successfully applied in the molecular logic gate, determination of HClO in environmental water samples, and portable HClO detection. [ABSTRACT FROM AUTHOR]

Heavy metals such as Iron, Copper, and Zinc are micro-essential trace metal and involve animportant biological role, but it quickly turns toxic at exceeding the permissible limit, causing gastrointestinal irritation, liver, bone, and kidney damage, as well as disorders including Wilson's, Parkinson's, and Alzheimer's. It is important to detect the metal ions as well as their concentration quickly and affordable cost using organic probes. Among the organic probes,the coumarin fluorescent probe shows a very prominent candidate with heavy metal ions. Therefore, in the present review, we reviewed the very recent literature the identify the heavy metals using modified coumarin fluorescent probes. Readers will get information quickly about the method of preparation of modified coumarin core and their use as fluorescent probes with heavy metals using absorption and emission spectroscopic methods along with the probable mechanistic pathway of detection. [ABSTRACT FROM AUTHOR]

Herein, a turn "Off/On" fluorescence probe based on ZnO quantum dots (ZnO-QDs) has been proposed and successfully utilized for the determination of Ara-C (cytarabine) using ceric ions (Ce4+) as quencher and ethylenediamine (ED) as a linker. The probe is based initially on the quenching effect of Ce4+ ions on the strong native fluorescence of ZnO-QDs forming the Turn Off system (Ce@ZnO-QDs) that believed to occur due to the aggregation-induced quenching (AIQ) mechanism. The second step is the addition of Ara-C in the presence of ethylenediamine (ED) that encourages the formation of Ara-C/ED/Ce4+ as well as the release of the free ZnO-QDs, leading to the recovery of the fluorescence intensity. The developed sensing platform shows a linear response towards Ara-C over the range of 10 to 1000 ng mL−1 giving a limit of detection (LOD) and limit of quantitation (LOQ) of 1.22 ng mL−1 and 3.70 ng mL−1, respectively. A dispersive magnetic solid phase micro-extraction (dMSPE) method was developed and optimized for the extraction of Ara-C in spiked human plasma using thiol-modified magnetite nanoparticles (S-MNPs). The proposed platform exhibits good sensitivity toward Ara-C in the presence of different interfering substances. Excellent recoveries are obtained after spiking different concentrations of Ara-C into rabbit plasma samples. The validated experimental parameters have been successfully applied to monitor the pharmacokinetic profile of Ara-C in rabbit plasma. A detailed adsorption kinetics study has been carried out to provide a deep insight into the adsorption behavior of Ara-C on the thiol-doped-magnetite nanoparticles. The greenness assessment of the proposed method was achieved and compared with other reported methods using two tools of greenness; the green analytical procedure index (GAPI) and the analytical greenness calculator AGREE. [ABSTRACT FROM AUTHOR]

Widely utilized in the chemical industry and agriculture, hydrazine is easily absorbed by living things and can cause physical harm when in touch for an extended period of time. As a result, a novel cinnamaldehyde chalcone C5 was produced by Friedel Crafts process and aldol condensation reaction. Triphenylamine was used as the raw material for hydrazine determination in both reactions. Chalcone C5 exhibits significant AIE behavior in a mixed mixture of ethanol and water in addition to having great selectivity and a low detection limit (0.119 nm) for hydrazine. The solvent effect test revealed a linear relationship between the Stokes shift of C5 in the solvent and the rise in solvent orientation polarization. It is important to note that C5 is not harmful to MCF-7 cells, mouse kidney cells, or pig kidney cells. Furthermore, research on cell imaging has demonstrated that probe C5 may be utilized to image the fluorescence of hydrazine in active MCF-7 cells. [ABSTRACT FROM AUTHOR]

Based on the N-redox mechanism, a turn-on near-infrared fluorescence probe (SWJT-15) with cyano isophorone as skeleton was designed and synthesized for the detection of ferrous ions (Fe2+). The probe has a lower detection limit (83 nM) and fast response (200 s) to Fe2+ ions. And the probe has unique selectivity and good anti-interference performance against Fe2+ ions compared to other metal ions. Moreover, the probe has been successfully applied to imaging Fe2+ ions in HeLa cells. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Carbon dots have been widely focused on the field of sensing and detection due to their excellent optical property. Herein, novel orange fluorescent nitrogen and chlorine co-doped carbon dots (N,Cl-CDs) are obtained by one-pot hydrothermal method using o-phenylenediamine and neutral red. Based on the inner filter effect, the prepared N,Cl-CDs can be innovatively developed as an effective "signal-off" multifunctional sensing platform for sensitive determination of tetracycline. The proposed sensor was utilized to realize the determination of tetracycline in Rirver water samples/milk samples (λex = 390 nm, λem = 606 nm) with satisfactory recoveries and relative standard deviations. The linear range of are 0.05 to 45 μM and 45 to135 μM, and detection limit is 3.9 nM (3σ/m). Meanwhile, the luminescent intensity of N,Cl-CDs was reduced gradually when pH changed continuously from 12 to 2, showing a pH-responsive fluorescence property with two linear ranges of pH 3–7 and pH 7–10. In addition, due to the characteristics of low toxicity and excellent biocompatibility, the N, Cl-CDs were also used in the imaging of oocystis cells, which is hopeful to realize the detection of tetracycline in living cells. [ABSTRACT FROM AUTHOR]

In order to better monitor the content of Fe3+ and H2S in the biological environment, two new fluorescent probes were designed and synthesized. With the addition of Fe3+, the strong fluorescence emission of two probes was significantly quenched due to the paramagnetic effect of Fe3+. With the further addition of S2−, the fluorescence intensity was quickly restored. Two probes showed high selectivity and strong sensitivity for the detection of Fe3+ and S2−, and the fluorescence intensity "ON-OFF-ON" was accompanied with the interaction process. At the same time, two probes displayed good anti-interference ability which was not interfered by the existence of other ions. In addition, two probes illustrated fast response time to Fe3+, S2− and small cytotoxicity to cells. Therefore, two probes can provide a potential ideal tool for detecting Fe3+ and H2S in organisms and the environment. [ABSTRACT FROM AUTHOR]

Millions of deaths occur each year due to the late diagnosis of abnormal cellular growth within the body. However, the devastating impact of this can be significantly reduced if cancer metastasis is detected early through the use of enzymatic biomarkers. Among several biomarkers, γ-glutamyltranspeptidase (GGT) stands out as a member of the aminopeptidase family. It is primarily found on the surface of cancer cells such as glioma, ovarian, lung, and prostate cancer, without being overexpressed in normal cells or tissues. Recent years have witnessed significant progress in the field of cancer monitoring and imaging. Fluorescence sensing techniques have been employed, utilizing organic small molecular probes with enzyme-specific recognition sites. These probes emit a fluorescent signal upon interacting with GGT, enabling the imaging, identification, and differentiation of normal and cancerous cells, tissues, and organs. This review article presents a concise overview of recent progress in fluorescent probes developed for the selective detection of GGT, focusing on their applications in cancer imaging. It highlights the observed alterations in the fluorescence and absorption spectra of the probes before and after interaction with GGT. Additionally, the study investigates the changes in the probe molecule's structure following enzyme treatment, evaluates the sensor's detection limit, and consolidated imaging studies conducted using confocal fluorescence analysis. This comprehensive survey is expected to contribute to the advancement of sensing techniques for biomarker detection and cancer imaging, providing valuable insights for refining methodologies and inspiring future developments in this field. [ABSTRACT FROM AUTHOR]

We present the synthesis of a new oxacalix[4]arene system, DMANSOC, wherein two 5-(dimethylamino)-1-naphthalene sulfonamide subunits are attached to the lower rims of the basic oxacalix[4]arene platform. Extensive spectrophotometric studies were conducted to investigate the selectivity and sensitivity of DMANSOC towards nitroaromatic explosives. Detailed analysis of spectrophotometric data, utilizing techniques such as Stern-Volmer, Benesi-Hildebrand, Job's plot, and interference study, unequivocally demonstrated the effectiveness of DMANSOC as a highly efficient fluorescent sensor for 2,4,6-trinitrophenol explosive (TNP) detection in an aqueous medium. The sensor exhibited a linear concentration range of 7.5 μM to 50 μM, with a low detection limit of 4.64 μM and a high binding affinity of 2.45 × 104 M towards TNP. Furthermore, the efficiency of the sensor in environmental samples contaminated with TNP was evaluated, yielding excellent recovery rates. Complementary DFT calculations and molecular dynamics simulations were performed to elucidate the mechanism behind the selective fluorescence quenching of DMANSOC in the presence of TNP. [ABSTRACT FROM AUTHOR]

Fluorescent probes are sensitive, selective, nontoxic in detection and thus provided a new solution in biomedical, environmental monitoring, and food safety. In order to expand the application of fluorescent probes in various fields, the paper discusses the design, synthesis, and characterization of fluorescent probes, explores new design and development trends of fluorescent probes in various fields, and improves the performance and applicability of fluorescent probes by using new materials and technologies to meet the evolving demands of molecular detection in various fields. [ABSTRACT FROM AUTHOR]

In this study, a citalopram optical nano-sensor was developed. Citalopram is a well-known antidepressant drug that reduces the reuptake of serotonin in neurons as a result, serotonin neurotransmission, the primary response to antidepressant treatments, increases in many parts of the brain. This study introduces a carbon quantum dots (CQDs)-based optical nanosensor for rapid detection of citalopram. This fluorescent nanosensor was made through the polymerization of tetraethyl orthosilicate in the presence of CQDs as the fluorescent materials and citalopram as the template molecule. Following the polymerization, the templated molecules were washed and removed from the structure, and the matrix of the polymer was left with some cavities that resembled citalopram in terms of size and shape. The final structure which is used as a chemical nanosensor, is named carbon quantum dots embedded silica molecularly imprinted polymer (CQDs-SMIP). The materials used in designing nano-sensors were characterized using FTIR, UV/Vis, and fluorescence spectroscopy, as well as high-resolution transmission electron microscopy (HR-TEM), and field emission scanning electron microscopy (FESEM). CQDs-SMIP showed a strong fluorescence emission at 420 nm in the absence of the template molecule. The fluorescence intensity of the nanosensor decreased in the presence of citalopram. The correlation between the extent of the fluorescence quenching and the concentration of citalopram provided the nano-sensor signal. The nano-sensor was used to measure citalopram in complex matrices such as human plasma and urine samples with remarkable selectivity and sensitivity. The detection limit of 10.3 µg.L-1 over a linear range of 100 to 700 µg.L-1, and RSD of 3.15% was obtained. This nano-sensor was applied to analyze of citalopram in plasma and human urine samples with remarkable results. [ABSTRACT FROM AUTHOR]

A new carbazole-coupled tetrakis-(1 H-pyrrole-2-carbaldehyde) anion receptor 1 has been designed and synthesized. Anion binding studies in organic media using fluorescence and UV-vis spectroscopy revealed that receptor 1 is capable of sensing HP2O73- with high selectivity. Addition of HP2O73- to THF solution of 1 resulted in the emergence of a new broad band at longer wavelength along with quenching of the original emission band forming a ratiometric response. Based on dynamic light scattering (DLS) experiment and fluorescence lifetime measurement, we propose that the emergence of new emission band in the presence of HP2O73- ion is due to the aggregation-induced excimer formation. [ABSTRACT FROM AUTHOR]

The accurate and effective identification of hydrogen sulfide holds great significance for environmental monitoring. Azide-binding fluorescent probes are powerful tools for hydrogen sulfide detection. We combined the 2'-Hydroxychalcone scaffold with azide moiety to construct probe Chal-N3, the electron-withdrawing azide moiety was utilized to block the ESIPT process of 2'-Hydroxychalcone and quenches the fluorescence. The fluorescent probe was triggered with the addition of hydrogen sulfide, accompanied by great fluorescence intensity enhancement with a large Stokes shift. With excellent fluorescence properties including high sensitivity, specificity selectivity, and wider pH range tolerance, the probe was successfully applied to natural water samples. [ABSTRACT FROM AUTHOR]

Herein, we have prepared a 5,10,15,20-Tetrakis(4-hydroxyphenyl) porphyrin (P) which acts as a probe for selective and sensitive detection of Bi3+ ions. Probe P was obtained by reacting pyrrole with 4-hydroxyl benzaldehyde and characterized by NMR, IR, and ESI-MS. All photo-physical studies of P were tested in DMSO:H2O (8:2, v/v) media by spectrophotometry and spectrofluorometry respectively. The selectivity of P was tested with different metal ions in solution as well as in the solid phase, only Bi3+ showed red fluorescence quenching while with other metal ions, no such effect was observed. The Job's plot unveiled the 1:1 stoichiometric binding ratio of the probe with Bi3+ and anticipated association constant of 3.4 ×105 M-1, whereas the Stern-Volmer quenching constant was noticed to be 5.6 ×105 M-1. Probe P could detect Bi3+ down to 27 nM by spectrofluorometric. The binding mechanism of P with Bi3+ was well supported with NMR, mass, and DFT studies. Further, the P was applied for the quantitative determination of Bi3+ in various water samples and the biocompatibility of P was examined using neuro 2A (N2a) cells. Overall, probe P proves promising for the detection of Bi3+ in the semi-aqueous phase and it is the first report as a colorimetric and fluorogenic probe. [ABSTRACT FROM AUTHOR]

A novel naphthalimide-substituted calix[4]triazacrown-5 (Nap-Calix) at cone conformation was designed and synthesized to employ as a fluorescent probe, which enables the simultaneously detection of Co2+ and Cd2+ metal ions as well as dopamine (DA). 1H-NMR, 13C-NMR, ESI–MS and elemental analysis techniques were carried out to characterize its structure. Cation binding property of Nap-Calix against various metal ions such as Ba2+, Co2+, Ni2+, Pb2+, Zn2+, and Cd2+ exhibited that the sensor selectively binds to Co2+ and Cd2+ metal ions with a remarkable affinity. Introduction of Co2+ and Cd2+ metal ions to a solution of Nap-Calix in DMF/water (1:1, v/v) resulted with a new emission band at 370 nm when excited at 283 nm. In addition, the fluorescence sensing affinity of the probe Nap-Calix against a catecholamine neurotransmitter (dopamine) was investigated in a wide range of concentration of DA (0–0.1 mmol L−1) in 50% DMF/PBS (pH = 5.0). The fluorescence intensity of Nap-Calix, with excitation/emission peaks at 283/327 nm, is highly enhanced by DA. It was also observed that Nap-Calix exhibits excellent fluorescence behavior towards DA with a very low detection limit as 0.21 µmol L−1. [ABSTRACT FROM AUTHOR]

A new carbazole-coupled tetrakis-(1 H-pyrrole-2-carbaldehyde) anion receptor 1 has been designed and synthesized. Anion binding studies in organic media using fluorescence and UV-vis spectroscopy revealed that receptor 1 is capable of sensing HP2O73- with high selectivity. Addition of HP2O73- to THF solution of 1 resulted in the emergence of a new broad band at longer wavelength along with quenching of the original emission band forming a ratiometric response. Based on dynamic light scattering (DLS) experiment and fluorescence lifetime measurement, we propose that the emergence of new emission band in the presence of HP2O73- ion is due to the aggregation-induced excimer formation. [ABSTRACT FROM AUTHOR]

A novel 1,8-naphthalimide fluorescent probe (BNAS) containing 2-thiopheneethylamine moiety was designed and synthesized for analyzing the composition of N,N-dimethylformamide (DMF)/deionized water (H2O) mixtures. With the increase of DMF content, the fluorescence of the system was enhanced from dark to bright yellow-green. Taking 15% (volume) DMF content as the dividing point, the fluorescence intensity of the system at 535 nm showed two good linear relationships with the DMF content 1–15% and 15–99%, based on which the composition of the DMF/H2O mixtures with a volume ratio of 1/99–99/1 could be quickly and efficiently analyzed with high selectivity and sensitivity. BNAS can be applied in real sample assay and further be loaded onto filter paper to make a portable sensor. The mechanism of BNAS response to DMF/H2O composition was also explored. [ABSTRACT FROM AUTHOR]

A fluorescent probe Y((1,1'-([1,1'-biphenyl]-4,4'-diylbis(3-(2-hydroxyphenyl)-4,5-dihydro-1H-pyrazole-5,1-diyl)) bis(ethan-1-one))) was designed and synthesized, which could be used to Cu2+ and Fe3+ sensors. Through the study of optical properties, the probe Y shows good selectivity and sensitivity to Cu2+ and Fe3+ in aqueous tetrahydrofuran solution [10.0 mM HEPES, pH 7.4, THF-H2O = 9:1(v/v)] with has excellent anti-interference performance, and its detection limits were 0.931 uΜ for Cu2+ and 0.401uΜ for Fe3+. The coordination mechanism of probe Y with Cu2+ and Fe3+ was speculated and verified at DFT level and HRNM. By Hela cytotoxicity and imaging tests, probe Y not only has good biocompatibility, but also can be used for sensing Cu2+ in cells. [ABSTRACT FROM AUTHOR]

A novel dansyl-based fluorescent probe (DG) was designed via the introduction of a dipeptide, glycyl-L-glutamine. DG showed good selectivity and sensitivity towards Cu2+ in aqueous solutions in the pH span of ~ 6–12. The coordination of Cu2+ with the dipeptide moiety led to the fluorescent quenching of the dansyl fluorophore. The association constant value for Cu2+ was 0.78 × 104 M− 1 in a 1 to 1 stoichiometric ratio. The detection limit in HEPES buffer solution (10 mM, pH 7.4) was 1.52 µM. DG also showed strong anti-interference capability in the presence of other metal ions. It was worth noting that DG maintained the detection ability towards Cu2+ in real water samples and cell imaging, implying the potential application opportunities in complicated environments. [ABSTRACT FROM AUTHOR]

Most fluorescent probes based on carbon dots (CDs) fluorescence color or intensity change are still used for detection in solution, but in practical fluorescence detection applications, detection in the solid state is necessary. Therefore, a CDs-based fluorescence sensing device is designed in this paper, which can be used for water detection in liquid and solid states. Using oPD as a single precursor, yellow fluorescent CDs (y-CDs) were prepared by hydrothermal method, which can be used in the field of water detection and anti-counterfeiting by using its solvent-sensitive properties. First, y-CDs can be used to visually and intelligently detect the water content in ethanol. Secondly, it can be used to detect the Relative Humidity (RH) of the environment by combining it with cellulose to form a fluorescent film. Finally, y-CDs can also be used as a fluorescent material for fluorescence anti-counterfeiting. [ABSTRACT FROM AUTHOR]

Hypochlorous acid (HClO), a highly reactive oxygen species, has important effects on human health. High selectivity and sensitivity remain challenges of fluorescent probes for detection of ClO− with a large Stokes shift. This work designed and synthesized a novel phenothiazine-based fluorescent probe TF which can detect ClO− by colorimetric and fluorescent dual signals. TF displayed turn-on fluorescence effect toward ClO− with high selectivity (≥ 28-folds) and sensitivity (LOD = 0.472 μM), fast response time (< 1 min) and large Stokes shift (150 nm) in PBS (pH = 7.4, 40% DMSO). Meanwhile, TF can visualize ClO− on the mung bean sprouts model and apply as testing strips for portable and rapid detecting ClO− by the naked eyes. A phenothiazine-based fluorescent probe with large Stokes shift was synthesized and its responding rapidly ability to detect ClO− was studied. [ABSTRACT FROM AUTHOR]

In this paper, a novel amino acid surface-functionalized semiconductor CdTe quantum dot fluorescent probe amidated by carboxyl and amide groups was synthesized to detect pyrophosphate ions (P2O74−, PPi). L-Arginine (L-Arg) was grafted onto cysteine modified CdTe quantum dots (Mea-CdTe QDs) to form a new L-Arginine-functionalized quantum dot fluorescent probe (L-Arg@Mea-CdTe). The prepared probe has good optical properties with multiple grafted functional groups on the surface. The guanidine group of the L-Arg@Mea-CdTe fluorescent probe is strongly basic and will be fully protonated under physiological conditions. The resulting hydrogen bonds bound to pyrophosphate lead to significant changes in the fluorescence of CdTe quantum dots. IR and XPS characterization were performed to confirm it. The addition of PPi induces a significant fluorescence quenching of L-Arg@Mea-CdTe in aqueous solution. The fluorescent QDs probe can also detect pyrophosphate with good sensitivity and anti-interference performance. The detection limit of the L-Arg@Mea-CdTe fluorescence probe for PPi is as low as 0.30 μM. In addition, the novel nano-fluorescent probe was successfully applied to detect PPi in water and in cell imaging. [ABSTRACT FROM AUTHOR]

The development of fluorescent probe for hydrazine (N2H4) detection has attracted much attention due to the important role of N2H4 plays in the fields of medicine, agriculture, biology and environments. In this paper, the optical properties and water solubility of two novel two-photon fluorescent molecular probes (Probe1 and Probe2) before and after the reaction with N2H4 are studied by using the density function theory. The results show that electronic distribution and transition dipole moment of the probes are obviously changed after the reaction with N2H4, thus the optical properties of the molecules are influenced and the detection of N2H4 are realized. In addition, photoinduced electron transfer processes for Probe1 and Probe2 in the presence of N2H4 are theoretically characterized, which explains the experimental observations from the microscopic mechanism. Special attention has been paid on the analysis of the two-photon absorption for the probes with the absence and presence of N2H4 by the response theory method. Both probes with good water solubility show large variation on the two-photon absorption cross section when reacts with N2H4. In particular, the two-photon absorption response of Probe2 is more obvious, so it possesses preferable two-photon fluorescence microscopic imaging ability. More importantly, the receptor effect on the sensing performances of the probes are demonstrated, providing a theoretical reference for the design and synthesis on more efficient two-photon fluorescence N2H4 probes. Our study provides necessary information on the response mechanism of the studied chemosensors and helps to establish the relationship between the structure and optical properties of two-photon fluorescence N2H4 probes. [ABSTRACT FROM AUTHOR]

Picric acid (PA) is a powerful nitro-aromatic explosive that harms the environment and human health. Developing non-toxic and low-cost sensors for the rapid detection of PA is essential. An environment-friendly fluorescent probe for PA detection is designed based on carbon dots (CDs) directly separated from edible soy sauce by silica gel column chromatography. Neither organic reagents nor heating process was needed to prepare CDs. The obtained CDs exhibit bright blue fluorescence, good water solubility, and photostability. The fluorescent probe for PA was developed according to the CD's fluorescence can be significantly quenched via the inner filter effect between CDs and PA. The linear range was 0.2–24 µM with a limit of detection of 70 nM. This proposed method was successfully employed to detect PA in the real water samples with satisfactory recoveries between 98.0–104.0%. Moreover, the CDs were suitable for fluorescence imaging of HeLa cells owing to their low toxicity and good biocompatibility. [ABSTRACT FROM AUTHOR]

Herein, we designed two fluorescent tetrasubstituted benzene sulfonyl appended Thiacalix[4]arene receptors named L1 and L2, which sensitively and selectively detect Sulfosulfuron among other herbicides and pesticides. The detection limit (LOD) was found to be 0.21 ppm and 0.35 ppm, and the enhancement constant (Ks) was determined to be 7.07 X 104 M−1 and 5.55 X 104 M−1 for L1 and L2, respectively. Using the non-linear regression method, the association constant was obtained as 2.1 X 104 M−1 and 2.23 X 104 M−1 whereas, the binding ratio was found to be 1:1 for both L1 and L2, respectively. Additionally, the interference studies show the selective nature of receptors for Sulfosulfuron among its sulfonylurea family. To further confirm the interaction mechanism, 1H-NMR spectroscopy, and a computational investigation were carried out, which validates the 1:1 binding ratio. The receptors were found to be recyclable in nature with simple acid–base treatment. This new approach of using supramolecules as fluorescent probes for sensitive and selective detection of herbicides is rare in the literature. [ABSTRACT FROM AUTHOR]

H2S was deemed as a toxic gradient in the realm of food and environment but plays pivotal pathophysiological roles in organisms. H2S instabilities and disturbances are always responsible for multiple disorders. We fabricated a H2S-responsive NIR fluorescent probe (HT) for H2S detection and evaluation both in vitro and in vivo. HT exhibited rapid H2S response within 5 min, accompanied with visible color change and NIR fluorescence generation, and the fluorescent intensities were linearly correlated with corresponding H2S concentrations. When HT was incubated with A549 cells, the intracellular H2S and H2S fluctuations could be monitored ore rotundo via the responsive fluorescence. Meanwhile, when HT was co-administrated with H2S prodrug ADT-OH, the H2S release from ADT-OH could be visualized and monitored to evaluate its release efficacy. [ABSTRACT FROM AUTHOR]

Fluorescence image-guided surgery (FIGS) can serve as a tool to achieve successful resection of tumour tissues during surgery, serving as a surgical navigator for surgeons. FIGS relies on the use of fluorescent molecules that can specifically interact with cancer cells. In this work, we developed a new model of fluorescent probe based on benzothiazole-phenylamide moiety featuring the visible fluorophore nitrobenzoxadiazole (NBD), namely BPN-01. This compound was designed and synthesised for potential applications in the tissue biopsy examination and ex-vivo imaging during FIGS of solid cancers. The probe BPN-01 exhibited favourable spectroscopic properties, particularly in nonpolar and alkaline solvents. Moreover, in vitro fluorescence imaging revealed that the probe appeared to recognise and be internalised in the prostate (DU-145) and melanoma (B16-F10) cancer cells, but not in the normal cells (myoblast C2C12). The cytotoxicity studies revealed that probe BPN-01 was not toxic to the B16 cells, suggesting excellent biocompatibility. Furthermore, the computational analysis showed that the calculated binding affinity of the probe to both translocator protein 18 kDa (TSPO) and human epidermal growth factor receptor 2 (HER2) was considerably high. Hence, probe BPN-01 displays promising properties and may be valuable for visualising cancer cells in vitro. Furthermore, ligand 5 can potentially be labelled with NIR fluorophore and radionuclide, and serves as a dual imaging agent for in vivo applications. [ABSTRACT FROM AUTHOR]

Mercury ion is a global toxic and hazardous environmental pollutant. In this work, a facile and selective ratiometric fluorescent probe was constructed for the detection of mercury ion. The dual-emissive carbon dots (BYCDs) were fabricated by a one-pot hydrothermal method utilizing o-phenylenediamine and glycine as raw materials, and the prepared BYCDs had two independent fluorescence emission peaks at 426 nm and 543 nm under a single excitation wavelength. Based on the change of the intensity ratio of the two fluorescence emission peaks after the addition of Hg2+, a sensitive and selective ratiometric fluorescent probe based on BYCDs was constructed for the detection of Hg2+ with good linearity ranging from 0.95–50 μM and a detection limit of 0.27 μM. In addition, the recovery of this probe was satisfactory in the standard addition experiments of real water samples, and it could be applied to the analysis of Hg2+ in real water samples. [ABSTRACT FROM AUTHOR]

Mercury ion is a global toxic and hazardous environmental pollutant. In this work, a facile and selective ratiometric fluorescent probe was constructed for the detection of mercury ion. The dual-emissive carbon dots (BYCDs) were fabricated by a one-pot hydrothermal method utilizing o-phenylenediamine and glycine as raw materials, and the prepared BYCDs had two independent fluorescence emission peaks at 426 nm and 543 nm under a single excitation wavelength. Based on the change of the intensity ratio of the two fluorescence emission peaks after the addition of Hg2+, a sensitive and selective ratiometric fluorescent probe based on BYCDs was constructed for the detection of Hg2+ with good linearity ranging from 0.95–50 μM and a detection limit of 0.27 μM. In addition, the recovery of this probe was satisfactory in the standard addition experiments of real water samples, and it could be applied to the analysis of Hg2+ in real water samples. [ABSTRACT FROM AUTHOR]

A coumarin-rhodamine (RhBC)-fused colorimetric/fluorescent probe was designed and synthesized. The probe is effective in Cu2+/Hg2+ ion sensing. With the added Cu2+ to RhBC in water: N, N-dimethyl formamide (8:2, v/v), the cyclic form of RhBC, is converted into the open ring form and shows a clear color change from yellow to red. In the presence of additional participating cations, this moiety shows effectiveness for Cu2+ and Hg2+ ions. The RhBC's detection limit by the UV–visible spectral method was 8.81 × 10–6 M for Cu2+ ions and 2.26 × 10–5 M for Hg2+ ions. The detection limit in the fluorescence titration spectra was 2.02 × 10–7 M for Cu2+ ions and 6.11 × 10–8 M for Hg2+ ions. A 1:1 stoichiometric ratio was validated between the probe and copper/mercury ions by the method of the job plot. Moreover, RhBC-combined polyurethane electrospun nanofibers were synthesized. These nanofibers could detect Cu2+ in real samples with no complications, with an instinctive color difference from yellow to red and a weak orange color for mercury ions. [ABSTRACT FROM AUTHOR]

As an important endogenous gasotransmitter, hydrogen sulfide (H2S) has been implicated with a variety of biological processes and has attracted more and more attention for its key role in a wide range of pathological processes. However, lacking tools for H2S-specific in situ detection, the changes of endogenous H2S levels in the pathological progression of diseases are still unclear. In this work, a turn-on fluorescent probe (BF2-DBS) has been designed and synthesized by two-step reactions using 4-diethylaminosalicylaldehyde and 1,4-dimethylpyridinium iodide as raw materials. Probe BF2-DBS displays high selectivity and sensitivity to H2S with a large Stokes shift and good anti-interference ability. The practical application of probe BF2-DBS to detect endogenous H2S was evaluated in living HeLa cells. [ABSTRACT FROM AUTHOR]

A novel conjugated polymer PCZBTA-TBZ containing thiabendazole as recognition unit was synthesized via Suzuki coupling reaction, and its structural characterization, spectroscopic analysis and photophysical properties were investigated. In the metal ion response study, the addition of Cu2+ led to the occurrence of the photoinduced electron transfer (PET) mechanism, which significantly quenched the fluorescence of the polymer PCZBTA-TBZ with a quenching effect of 98%. Furthermore, I- can significantly quench the fluorescence of the polymer, but other anions have no such effect. According to the density functional theory calculation, compared with other polycarbazoles or other alternative copolymers containing carbazole, with alternating carbazole and triazole enhances the electron mobility and reduces the energy band gap of the polymer. Due to the strong coordination ability between Cu2+ and Cys, the adding Cys competes the Cu2+ in the [PCZBTA-TBZ-Cu2+] complex, blocking the occurrence of PET, and the fluorescence intensity of PCZBTA-TBZ is restored. The addition of other amino acids caused almost no change. The polymer is expected to be used for dual fluorescence detection of specific metal ions and Cys. [ABSTRACT FROM AUTHOR]

As one of the most toxic metals, Mercury ions cause serious environmental pollution and threaten the health of living organisms. Hence, we designed and synthesised a new near-infrared (NIR) ratiometric fluorescent probe toward monitoring of Hg2+ based on quinoline-fused rhodamine dye. Owing to the specific spirolactam ring-opening reaction, the probe exhibits a ratiometric fluorescent change after treatment of Hg2+ with increased emission in NIR and significantly reduced emission in visible region. The specific response mechanism and dual-channel fluorescence change allow the probe to have remarkable detection selectivity, fast response and high detection sensitivity. Moreover, with the properties of excellent cell permeability and low cytotoxicity, probe can be applied as detection tool for mercury ions with dual-channel ratiometric fluorescence imaging in living cell. [ABSTRACT FROM AUTHOR]

A novel D-π-A type fluorescent probe L(NO3) for Cu (II) sensing was designed and fully characterized. The probe consists of a styryl-pyridine cation fluorescent group and a di-(2-picolyl)amine (DPA) receptor unit, which are linked by a phenyl group to form an electron donor-π-acceptor (D-π-A) conjugate system, especially the introduction of a nitrate counter anion for significantly enhanced water solubility of the probe. Fluorescence titration studies of the probe L(NO3) showed a higher selectivity for Cu2+ than other metal ions, and the emission spectrum was strongly quenched upon binding. The competitive binding assay and the low detection limit (0.932 µM) showed that the probe L(NO3) had strong anti-interference ability and excellent Cu2+ detection performance. The binding ratio of probe L(NO3) and Cu2+ was determined from Job's plot to be 1:1, which is consistent with the results obtained from X-ray crystal structures. Meanwhile, the probe showed instantaneous chemical reversibility when titrated with EDTA solution, indicating potential recycling properties of the probe. In addition, the design of inexpensive fluorescent test strips can perform the on-site and real-time detection Cu2+ with a color recognition application. [ABSTRACT FROM AUTHOR]

Special attention is given to the development of rapid and sensitive detection of nitroaromatic explosives for homeland security and environmental concerns. As part of our contribution to the detection of nitroaromatic explosives, fluorescent materials (A), (B) and (C) were synthesized from the reaction of 1,2-diaminocyclohexane with pyrene-1-carbaldehyde, anthracene-9-carbaldehyde and 2-hydroxy-1-naphthaldehyde, respectively. The structures of the prepared fluorescent azomethine probes were confirmed using FTIR, 1H-NMR and 13C-NMR spectroscopies. The basis of the study is the use of the synthesized materials as fluorescent probes in the photophysical and fluorescence detection of some nitroaromatic explosives. Emission increases occurred due to aggregation caused by π-π stacking in synthesized azomethines. To measure the nitroaromatic detection capabilities of fluorescence probes, fluorescence titration experiments were performed using the photoluminescence spectroscopy. It was observed that compound A containing pyrene ring provided the best emission intensity-increasing effect due to aggregation with the lowest LOD value (14.96 μM) for the sensing of 4-nitrophenol. In compounds B and C, nitrobenzene with the lowest LOD (16.15 μM and 23.49 μM respectively) caused the most regular emission increase, followed by picric acid. [ABSTRACT FROM AUTHOR]