A cyanobiphenyl-based fluorescent ''lighting-up'' sensor for highly selective and sensitive recognition of Al3+: Theoretical, practical and bioimaging studies.

The recognition of toxic Al3+ in foods and biosystems has of great interest to researchers. Herein, a novel cyanobiphenyl-based chemosensor CATH (E)-N'-((4'-cyano-4-hydroxy-[1,1'-biphenyl]-3-yl)methylene)thiophene-2-carbohydrazide was fabricated and shown to recognize Al3+ in HEPES buffer:EtOH (90:10, v:v, pH = 7.4) by ''lighting-up'' fluorescence sensing. The CATH evidenced high sensitivity (LOD = 13.1 nM) and excellent selectivity to Al3+ over competing cations. The Job's plot, TOF-MS and theoretical computation studies were performed to probe the binding mechanism of Al3+ to CATH. Additionally; CATH was successfully utilized to practical applications and employed to recover of Al3+ from different food samples. More importantly, it was employed to intracellular Al3+ detection in living cells including THLE2 and HepG2.

Ultrasensitive detection of Cu2+: A cyanobiphenyl-based colorimetric and fluorescence chemosensor and its Smartphone and food sample applications.

A new cyanobiphenyl-based compound 4-hydroxy-3-(((4-(phenylamino)phenyl)imino)methyl)-[1,1-biphenyl]-4-carbonitrile (PEBP) for Cu2+ detection was fabricated and successfully characterized. PEBP was employed as a sensor for Cu2+ sensing and used as an extremely fast responsive colorimetric and ''ON/OFF'' fluorescent sensor in H2O:CH3CN (40:60, v/v). Highly selective fluorescence response of PEBP to Cu2+ yielded an excellently low detection limit of 20.4 nM. Binding stoichiometry for PEBP-Cu2+ was found to be 2:1 by Job's plot study, as well MALDI TOF-MS data, and the binding constant was computed as 0.62 × 102 M-1/2. The validation study was employed using analytical parameters and statistical tests. To understand the binding capability, density functional theory (DFT) study was performed. Smartphone and applications for different food and drinking water samples were successfully constructed for Cu2+ detection, and the findings revealed that PEBP could be easily employed for in-site Cu2+detection without sophisticated instrument.

A novel ratiometric fluorescent and colorimetric sensor based on a 1,8-naphthalimide derivative for nanomolar Cu2+ sensing: smartphone and food applications.

A novel 1,8-naphthalimide-based chemical sensor 3-((2-(2-butyl-1,3-dioxo-2,3-dihydro-1H-benzo[de]isoquinoline-6-yl)hydrazone-o)methyl)-4-hydroxy-[1,1-biphenyl]-4-carbonitrile (BUDIN) with ratiometric fluorescence behavior, as well as "naked-eye" response was developed for the sensitive and specific determination of Cu2+ at nanomolar levels. With the addition of different amounts of Cu2+, the emission of BUDIN varied continually, leading to colour changes from yellow to blue (λem = 532 nm to 462 nm) due to intra-ligand charge transfer (ILCT) and metal-ligand charge transfer (MCLT). BUDIN can detect Cu2+ quantitatively with a detection limit of 17 nM. Job's plot, MALDI TOF MS and TOF MS findings revealed that the binding stoichiometry of BUDIN and Cu2+ was 2 : 1. Furthermore, the theoretical computation data strongly supported the optical response of BUDIN toward Cu2+. Smartphone digital imaging studies proved that BUDIN can be utilized as an outstanding chemical sensor for the on-site detection of Cu2+ without the need for sophisticated equipment, with a detection limit of 17.8 µM. The findings also presented that BUDIN is a very effective chemosensor for Cu2+ in real food samples with quite a simple operation.

Propylimidazole Functionalized Coumarin Derivative as Dual Responsive Fluorescent Chemoprobe for Picric Acid and Fe3+ Recognition: DFT and Natural Spring Water Applications.

A propylimidazole functionalized coumarin derivative (IPC) was fabricated for the first time and applied as a dual responsive fluorescent chemoprobe for sensitive and selective recognition of picric acid (PA) and Fe3+. Strong fluorescence quenching phenomena of the IPC were observed in H2O/ACN (5/95, v/v) medium (λem=408 nm) upon the additions of Fe3+or PA. The fabricated dual responsive IPC offered good selectivity and sensitivity with the low limit of detection values (0.92 µM for PA and 0.22 µM for Fe3+) lower than the acceptable amounts of Fe3+ and PA by the international official authorities. The validation study for the chemoprobe IPC for PA and Fe3+ was also performed. The interaction phenomena of IPC with PA and Fe3+ based on the findings of a range of experiments were considered and DFT computations were done to verify their recognition mechanisms. The sensing phenomena of IPC towards PA (1:1) and Fe3+ (3:1) were confirmed by the MALDI TOF-MS, FT-IR, 1H-NMR titration and Job's methods. Furthermore, the compound IPC was effectively applied as a fluorescent sensor for Fe3+ and PA detection in real natural spring water samples.

A rapid diagnostic approach for gastric and colon cancers via Fourier transform mid-infrared spectroscopy coupled with chemometrics from paraffin-embedded tissues.

This paper describes the feasibility of Attenuated total reflection-Fourier transform mid-infrared (ATR-MIR) spectroscopy method coupled with chemometrics for the rapid diagnostic approach and screening spectral changes for gastric and colon cancers from paraffin-embedded tissues. A total number of 82 tissue samples were analyzed by a simple ATR-MIR method combined with PCA, HCA, SIMCA and LDA methodologies. Spectral analyses showed significant differences for the molecular contents particularly about the lipid, nucleic acid, protein and other biomolecules in the samples of gastric cancer (GC) and colon cancer (CC) groups from their control/healthy groups. Significant changes in the characteristic of these molecules were only observed for cancer groups based upon the increment in their biosynthesis, and they could be utilized as diagnostic spectral biomarkers. Under the optimum conditions, SIMCA provided excellent classification for diseased and control groups, with 5% significance level. As well, 97.75% of the studied tissue samples were correctly discriminated on the basis of their origin by LDA. Consequently, the findings of this study highlighted the rapid diagnosis of gastric and colon cancer cases from paraffin-embedded tissues via ATR-MIR spectroscopy complemented with chemometrics.

A simple and rapid determination of Al(III) in natural water samples using dispersive liquid-liquid microextraction after complexation with a novel antipyrine-based Schiff base reagent.

The purpose of this study is the development of a novel strategy for the determination of Al3+ ions using the combination of dispersive liquid-liquid microextraction (DLLME) and UV-Vis spectrophotometry. The method is grounded in the complexation between a novel antipyrine-based Schiff base reagent (EHMP) and Al3+ ions. Aluminum concentrations were detected using UV-Vis spectrophotometry at 260 nm and this technique was optimized using the absorbance value of EHMP-Al complex. pH, mixing period, type and volume of organic solvent, etc. were optimized stepwise in order to find out optimum experimental conditions. The limit of detection and the limit of quantification values for the improved analytical method were to be estimated 0.31 and 1.03 µmol.L-1, respectively. The new strategy was successfully performed to define Al3+ ions in natural water samples with RSD values (84.01-107.71%) and recovery values (0.01-0.09%).

Fabrication and sensing properties of phenolphthalein based colorimetric and turn-on fluorogenic probe for CO32- detection and its living-cell imaging application.

Herein, an easy assembled colorimetric and ''turn-on'' fluorescent sensor (probe P4SC) based on phenolphthalein was developed for carbonate ion (CO32-) sensing in a mixture of EtOH/H2O (v/v, 80/20, pH = 7, Britton-Robinson buffer) media. The probe P4SC demonstrated high sensitive and selective monitoring toward CO32- over other competitive anions. Interaction of CO32- with the probe P4SC resulted in a significant increment in emission intensity at λem = 498 nm (λex = 384 nm) due to the strategy of blocking the photo induced electron transfer (PET) mechanism. 1H NMR titration and Job's methods, as well as the theoretical study were carried out to support the probable stoichiometry of the reaction (1:2) between P4SC and CO32-. The binding constant of the probe P4SC with CO32- was calculated as 2.56 × 1010 M-2. The probe P4SC providing rapid response time (~0.5 min) with a satisfactorily low detection limit (14.7 nM) may be useful as a valuable realistic sensor. The imaging studies on the liver cancer cells (HepG2) shows the great potential of the probe P4SC for the sensation of intracellular CO32- anions. Furthermore, the satisfactory recovery and RSD values obtained for water application confirming that the probe P4SC could be applied to sensing of CO32- ion.

A novel phenolphthalein-based fluorescent sensor for Al3+ sensing in drinking water and herbal tea samples.

In this study, 3,3-bis(4-hydroxy-3-((E)-((4-hydroxyphenyl)imino)methyl) phenyl)isobenzofuran-1(3H)-one (HMBP) was designed as a ''turn-on″ fluorogenic chemosensor to detect Al3+. Studies were performed in C2H5OH-HEPES (v/v, 9/1, pH 7.0) media at λem = 475 nm. The LOD value was found to be 0.113 µM. The stoichiometric ratio of HMBP-Al3+ was determined as 1:2 by Job's plot and ESI-MS as well as 1H NMR titration. The binding constant of chemosensor HMBP with Al3+ from the Benesi-Hildebrand equation was determined to be 1.21 × 108 M-1. The quantum (Φ) yields were obtained as 0.040 and 0.775 for the chemosensor HMBP and HMBP-Al3+, respectively. The response of the chemosensor HMBP towards Al3+ was attributed to the strategies of blocking the photo-induced electron transfer (PET) and CN isomerisation mechanisms. Finally, the sensing of the chemosensor HMBP for the determination of Al3+ in real food samples, drinking waters and herbal teas, were employed.

Fluorescent sensing platform for low-cost detection of Cu2+ by coumarin derivative: DFT calculation and practical application in herbal and black tea samples.

A fluorogenic probe based on a coumarin-derivative for Cu2+ sensing in CH3CN/H2O media (v/v, 95/5, 5.0 µM) was developed and applied in real samples. 3-(4-chlorophenyl)-6,7-dihydroxy-coumarin (MCPC) probe was obtained by synthetic methodologies and identified by spectral techniques. The probe MCPC showed remarkable changes with a "turn-off" fluorogenic sensing approach for the monitoring of Cu2+ at 456 nm under an excitation wavelength of 366 nm. The response time of the probe MCPC was founded as only 1 min. The detection limit of the probe MCPC was recorded to be 1.47 nM. The binding constant and possible stoichiometric ratio (1:1) values were determined by Benesi-Hildebrand and Job's plot systems, respectively. The mechanism of the probe MCPC with Cu2+ was further confirmed by ESI-MS and FT-IR analyses, as well as supported by theoretical calculations. Furthermore, the probe MCPC was successfully employed for the practical applications to sense Cu2+ in different herbal and black tea samples. The proposed sensing method was also verified by ICP-OES method.

A novel fluorescent probe based on isocoumarin for Hg2+ and Fe3+ ions and its application in live-cell imaging.

Synthesis of the 2-amino-4-phenyl-6- (isocoumarin-3-yl) -3-cyanopyridine (APICP) containing both isocoumarin and pyridine ring in its structure was carried out, and this compound was characterized by ATR-FTIR, 1H NMR, and 13C NMR spectral techniques. A fluorescence sensor determining Hg2+ and Fe3+ ions in DMSO/HEPES buffer solution (9/1 v/v, 5 µM, pH 7.0) was developed using the synthesized compound, and the detection limits of the sensor with exquisite selectivity were calculated as 8.12 nM and 5.51 nM for Hg2+ and Fe3+ ions, respectively. Jobs plot method was used to determine the stoichiometry of APICP-Hg2+/Fe3+ complexes as 2:1 and FT-IR and ESI-MS methods confirmed the results. Besides, cell growth inhibitory potentials of the sensor over HepG2 cells and in vivo fluorescent cell imaging experiments were conducted. Findings revealed the relatively low cytotoxic effects of the synthesized sensor (IC50: 0.541 ±â€¯0.039 mM), and it could be utilized as an intracellular imaging agent for the determination of Fe3+ and Hg2+ ions in biological systems.

Synchronous fluorescence spectroscopy combined with chemometrics for rapid assessment of cold-pressed grape seed oil adulteration: Qualitative and quantitative study.

This paper describes the feasibility of synchronous fluorescence (SyF) spectroscopy combined with multivariate data analysis for qualitative and quantitative determination of adulteration of cold pressed grape seed oil (GSO) with refined soybean oil (SBO). SyF spectroscopy data of oil samples were collected in the region of 250-800 nm at excitation-emission wavelength differences (∆λ) of 10, 20, 30, 40, 50, 60, 70 and 80 nm. Three different multivariate methods, namely principal component analysis (PCA), soft independent modeling of class analogies (SIMCA) and partial least square regression (PLSR) analysis were used for data analysis. To simulate the adulteration of cold pressed GSO with refined SBO, ninety-six adulterated samples were prepared at adulterant levels from 5% to 50%. HPLC-FLD method was used as reference in order to authenticate pure oils and binary oil mixtures. The SIMCA models provided an excellent classification for pure cold pressed GSO versus other vegetable oil samples, with a 95% significance level. The classification error rate of SyF spectroscopy for detecting SBO added to GSO was also better than 5%. PLSR calibration models constructed for the evaluation of GSO purity and for the adulterants SBOs were internally validated by the leave-one-out procedure (cross-validation) and their predictive ability was assessed by independent external validation sets. Under the optimum conditions, the plots of observed versus predicted values exhibited a good linearity (R2 > 0.99). The root mean square errors of calibration (RMSEC) and cross-validation (RMSECV) were in the range 0.55-4.46% and 2.14-5.35%, respectively. Excellent predicting capabilities were also obtained using an external validation set consisting of GSO adulterated with SBOs from different brands.

A Turn off-on Fluorescent Chemosensor for Sequential Determination of Mercury and Biothiols.

The selective and sensitive determination of biothiols in aqueous media has been great attention due to their important role in biological and pharmacological processes. We synthesized tryptophan functionalized perylene bisimide as a sensing chemosensor for mercury in aqueous solution. This complex between perylene dimide derivate (PDI/Trp) and mercury ions was evaluated and displayed to be turn on fluorescent chemosensor for the determination of biothiols in aqueous media. PDI/Trp showed fluorescence quenching in the presence of Hg2+ and the fluorescence was recovered after addition of biological thiols (cysteine, homocysteine and glutathione). Therefore, PDI/Trp can be employed as a fluorescence probe for the sequencial recognization of Hg2+ and biothiols in aqueous solution. Graphical Abstract ᅟ.

Selective and sensitive fluorescent and colorimetric chemosensor for detection of CO32- anions in aqueous solution and living cells.

A new colorimetric and fluorescent chemosensor for visual determination of carbonate ions was developed by the microwave assisted solvent free synthesis of 7,8-dihydroxy-3-(4-methylphenyl) coumarin (DHMC). The structural characterization of DHMC was confirmed by microanalysis and spectroscopy methods (MALDI-TOF, FT-IR, 1H NMR, 13C NMR, and 2D HETCOR). The binding behaviors of DHMC were investigated towards various anions by UV-vis and fluorescence spectroscopy. DHMC showed a selective and sensitive fluorometric and colorimetric responses towards carbonate ion over other anions. The detection limit of CO32- was found to be 1.03 µM. Moreover, the fluorescence imaging in living cells suggests that DHMC has a great potential in the biological imaging application. It has been demonstrated that DHMC can be used as a rapid and reliable sensor for the determination of carbonate anion in a variety of practical applications.

Coumarin Based Highly Selective "off-on-off" Type Novel Fluorescent Sensor for Cu2+ and S2- in Aqueous Solution.

Solvent free synthesis of 6,7-dihydroxy-3-(3-chlorophenyl) coumarin (CFHC) was designed and obtained by the interaction of 2-(2,4,5-trimethoxyphenyl)-1-(3-chlorophenyl)acrylonitrile with pyridinium hydrochloride in the presence of silica gel by using microwave irradiation. The characterization of CFHC was confirmed by FT-IR, 1H, 13C, 13C-APT and 2D HETCOR spectroscopy methods. The optical behavior of CFHC towards metal ions was investigated by UV-visible and fluorescence spectroscopy. CFHC showed "on-off" type fluorescence response towards Cu2+ with high selectivity in aqueous solution (CH3CN/H2O, 9/1, v/v). Once binding with Cu2+, CFHC-Cu2+ complex also displayed high selectivity for sulfide, resulting in "off-on" type sensing of sulfide anion. Graphical abstract Visual fluorescence changes upon addition of various metal ions (5.0 eq.) to CFHC in CH3CN/H2O (90:10, v/v) under UV excitation (365 nm).