Showing papers in "Journal of Fluorescence in 2020"
TL;DR: This review gives an overview of the important fluorescent sensors which are based on Schiff base, their approaches for molecular recognition, and their potential application in bioimaging studies.
Abstract: Fluorescent determinations of analytes have proven to be a powerful method due to their simplicity, low cost, detection limit, rapid photoluminescence response, and applicability to bioimaging. Fluorescence imaging as a powerful tool for monitoring biomolecules within the living systems. Schiff base has been extensively used as strongly absorbing and colorful chromophores in the design of chemosensors. In recent years, Schiff base based fluorescent probes have been developed for the detection of various toxic analytes and imaging of various analytes in biological systems. This review gives an overview of the important fluorescent sensors which are based on Schiff base, their approaches for molecular recognition, and their potential application in bioimaging studies.
73 citations
TL;DR: The morphology of prepared N-CDs was characterized by high-resolution transmission electron microscopy, energy dispersive X-ray spectroscopy (EDS), and selected area electron diffraction (SAED) method, and the optical properties of the preparation influenced the catalytic performance of NaBH4 in the reduction of methyl orange.
Abstract: Facile and fast hydrothermal process for the synthesis of nitrogen doped carbon dots (N-CDs) from Coccinia grandis (C. grandis) extract is discussed here. The morphology of prepared N-CDs was characterized by high-resolution transmission electron microscopy (HR-TEM), energy dispersive X-ray spectroscopy (EDS), and selected area electron diffraction (SAED) method. The optical properties of the prepared N-CDs were revealed by Ultraviolet-Visible (UV-Vis) and photoluminescence spectroscopy. X-ray diffraction (XRD) and Raman spectroscopic techniques were employed to examine the crystallinity and graphitization of prepared N-CDs. The nitrogen doping was confirmed by Fourier transform infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The prepared nitrogen doped carbon dots released blue fluorescence at 405 nm beneath the excitation of 310 nm. The prepared N-CDs influenced the catalytic performance of NaBH4 in the reduction of methyl orange. The rate constant for the reduction of organic dye (methyl orange) by NaBH4 in the presence of the prepared green catalyst was also determined.
46 citations
TL;DR: The results of UV-Vis and fluorescent spectra analyses, X-ray crystallographic study and DMol3 simulation and calculation indicate that the chelation-enhanced fluorescence (CHEF) recognition mechanism of the sensor H2L for Zn2+ is of its hindered PET process.
Abstract: A new unsymmetric tetradentate salamo-like chemical sensor H2L for fluorescent recognition of Zn2+ has been designed and synthesized. The sensor can recognize Zn2+ from other metal ions examined with selectivity, anti-interference, reliability and high sensitivity (LOD = 1.89 × 10−6 M) in ethanol/H2O solution. The results of UV-Vis and fluorescent spectra analyses, X-ray crystallographic study and DMol3 simulation and calculation (on Materials Studio) indicate that the chelation-enhanced fluorescence (CHEF) recognition mechanism of the sensor H2L for Zn2+ is of its hindered PET process. The sensor H2L for Zn2+ has excellent fluorescence characteristics and has potential application value in biological and environmental systems.
45 citations
TL;DR: CQDs which were firstly synthesized from roasted–chickpeas by a microwave-assisted pyrolysis and the whole synthesis procedure are environmentally friendly, but also the synthesized CQDs have shown many advantageous properties such as high fluorescence intensity, excellent photostability, and good water solubility.
Abstract: A simple method for the green synthesis of fluorescent carbon quantum dots (CQDs) has been developed by using roasted chickpea as carbon source in one-step without using any chemical. Interestingly, not only the carbon source of CQDs and the whole synthesis procedure are environmentally friendly, but also the synthesized CQDs have shown many advantageous properties such as high fluorescence intensity, excellent photostability, and good water solubility. CQDs which were firstly synthesized from roasted–chickpeas by a microwave-assisted pyrolysis have been characterized using UV-vis absorption spectroscopy, fluorescence spectroscopy, fourier transform infrared spectroscopy (FTIR) spectroscopy, X-ray diffraction (XRD) technique and transmission electron microscopy (TEM). In addition, the details of the structure have been revealed by the electron diffraction (SAED; selected-area electron diffraction) method based on the TEM images. The synthesized CQDs emits blue fluorescence under UV light (at 365 nm). A microwave oven (350 watts) was used to prepare CQDs in 120 s. The effect of various metal ions on the fluorescence intensity of CQDs was investigated in order to determine its utality in the detection of metal ions. It was determined that 1.38 mg/L of Fe3+ ions quenched the fluorescence intensity of the CQDs by 65%. The linear range is observed between 11.25 and 37.50 μM with limit of detection (LOD) and limit of quantification (LOQ) of 2.74 μM and 8.22 μM, respectively. CQDs which are highly selective and sensitive for Fe3+ ions was used to determine Fe3+ ions in certified reference material (CRM-SA-C). Fe3+ ions concentration was determined with precision values of more than 95% as intra-day and inter-day relative standard deviation (RSD%) is 5 at room temperature.
44 citations
TL;DR: The selective sensing property of C-dots towards Fe3+ ions provide avenue for biochemical analysis related to iron metabolism and diagnosis of anaemia and Excitation-dependent photoluminescence emission properties and pH-sensitivity of C -dots were studied in detail.
Abstract: A single step hydrothermal mode of carbon nanodots (C-dots) synthesis from house-hold kitchen garbage such as snake gourd peel extract was successfully carried out. Characterisation of green synthesized C-dots were accomplished using UV-Visible and FTIR spectroscopy, Spectrofluorimetry and HRTEM. C-dots exhibited an appreciable quantum yield of 28.6%. Excitation-dependent photoluminescence emission properties and pH-sensitivity of C-dots were also studied in detail. C-dots exhibited strikingly selective detection of Fe3+ ions via fluorescence quenching mechanism. Linearity was obtained in a concentration range of 10–100 μM with detection limit of 0.398 μM in accordance with the Stern-Volmer relation. The existence of oxygen containing functional moieties in luminescent C-dots could be attributed to the effectual complexation between the metal ion and C-dots. The selective sensing property of C-dots towards Fe3+ ions provide avenue for biochemical analysis related to iron metabolism and diagnosis of anaemia.
34 citations
TL;DR: AAPCDs showed minimal cytotoxicity in Multi Drug Resistant clinically isolated strains of gram positive and gram negative bacteria which may be employed for microbiology oriented experiments and suggest potential of multi-functional AAPCDs as nano-probes for various pharmaceutical, biomedical and bioengineering applications.
Abstract: The combination of an Ayurvedic wisdom and nanotechnology may help us to resolve the complex healthcare challenges. A facile and economical one-pot hydrothermal synthesis method has been adopted for preparing a blue fluorescent carbon dots (CDs) with a quantum yield of 15.10% from an Ayurvedic medicinal plant Andrographis paniculata (AP). The Andrographis paniculata derived CDs (AAPCDs) were then characterized using different techniques. Through High Performance Thin Layer Chromatography (HPTLC) profiling of the AP extract and the CDs, it was found that some of the phytoconstituents are retained as such while others may have been converted into their derivatives during the process of formation of CDs. The CDs are designed to possess cellular imaging of human breast carcinoma cells (MCF-7), apart from free radicals sensing and scavenging capabilities. AAPCDs showed minimal cytotoxicity in Multi Drug Resistant clinically isolated strains of gram positive and gram negative bacteria which may be employed for microbiology oriented experiments. These results suggest potential of multi-functional AAPCDs as nano-probes for various pharmaceutical, biomedical and bioengineering applications.
32 citations
TL;DR: In the present review, the colorimetric and ratiometric fluorescent probe synthesized by the authors in almost half decade are discussed.
Abstract: Colorimetric and ratiometric fluorescent probe for cations gain very well attention by the chemist, biologist and environmentalist. Metals has two sides, first is biolgical active for living creature and toxic nature for the ecosystem. From last three decades the scientists are contiously trying to find out the best solution for the detection of cations at micro as well as nanomolar levels. In the present review we discussed the colorimetric and ratiometric fluorescent probe synthesized by the authors in almost half decade.
31 citations
TL;DR: Fluorescence excitation-emission matrix spectroscopy was evaluated to study the decay of an azo-dye by a hydroxyl radical generated from catalytic Fe (III) on H 2 O 2 and showed that fluorescence signal reliably indicated the variations of the chemical groups and components during degradation, and the degradation could be divided into three stages.
Abstract: Chemical oxidation is a key technique used in dye wastewater treatment via the formation of hydroxyl radicals. To obtain optimal treatment effects, it is critical to understand the interaction of the molecular structure of the dye with the hydroxyl radical. We evaluated fluorescence excitation-emission matrix spectroscopy to study the decay of an azo-dye (Procion Red MX-5B) by a hydroxyl radical generated from catalytic Fe (III) on H2O2. Results showed that fluorescence signal reliably indicated the variations of the chemical groups and components during degradation, and the degradation could be divided into three stages: initial degradation (decolorisation), rapid intermediate degradation, and final degradation. Under control of uncorrected matrix correlation, the fluorescence fractions could be fitted successfully by parallel factor model (PARAFAC) model: two fluorescence components in initial degradation including mono substituted benzene and mono substituted naphthalene, three components as multi substituted benzene in rapid degradation, and no components could be resolved in the final degradation. The results from the study demonstrate the utility fluorescence characterization of dye degradation mechanisms and enhance the understanding of the degradation mechanisms.
28 citations
TL;DR: The HL chemosensor was found to be sensitive to Zn2+, Cd2+ and Hg2+ than some metal ions and its complexes emitted strong fluorescence, which gave a wide range of linearity with Zn3+, Hg3+ and Cd3+ in aqueous samples.
Abstract: Metal complexes were obtained by the reaction of zinc, cadmium and mercury(II) salts with Schiff base HL (N(salicylidene)benzylamine). HL was synthesized by the condensation reaction of benzylamine and 2-hydroxybenzaldehyde. The fluorescence properties of the Schiff base and its metal complexes were studied in ethanol-water solutions. HL was examined for its utility as a fuorescent chemosensor for the determination of Zn2+, Cd2+ and Hg2+ in aqueous samples. The HL chemosensor was found to be sensitive to Zn2+, Cd2+ and Hg2+ than some metal ions and its complexes emitted strong fluorescence at 452 nm for Zn2+ at 474 nm for Cd2+ and at 491 nm for Hg2+, respectively. It was determined that HL forms complexes with a ratio of 2:1 for Zn2+ and Hg2+ and with a ratio of 1:1 for Cd2+ by Job plots. For the detection of Zn2+, Cd2+ and Hg2+ in aqueous samples, pH, solvent type and ligand concentration were optimized for an analytical method based on HL chemosensor. HL gave a wide range of linearity with Zn2+, Hg2+ and Cd2+, the limit of detection was found to be 2.7 × 10-7 M, 7.5 × 10-7 M and 6.0 × 10-7 M, respectively.
27 citations
TL;DR: The preparation of a fluorescent sensor based on coumarin derivative for copper (II) ion sensing in CH 3 CN/HEPES media and demonstrates “turn on–off” fluorescence quenching in the presence of copper ( II) ions at 458 nm is reported.
Abstract: Herein, we report the preparation of a fluorescent sensor based on coumarin derivative for copper (II) ion sensing in CH3CN/HEPES media. 6,7–dihydroxy–3–(4–(trifluoro)methylphenyl)coumarin (HMAC) sensor was fabricated and analyzed by spectroscopic techniques. The sensor demonstrates “turn on–off” fluorescence quenching in the presence of copper (II) ions at 458 nm. A clear complex between the chemosensor HMAC and copper (II) ions was characterized by ESI–MS as well as the Job’s method. Also, the limit of detection (LOD, 3σ/k) value was determined as 24.5 nM in CH3CN/HEPES (95/5, v/v) buffer media (pH = 7.0). This value is lower than the admissible level of copper (II) ions in drinking water (maximum 31.5 μM) reported by EU Water Framework Directive (WFD) and World Health Organization (WHO) guidelines. The theoretical calculations (density functional theory, DFT) have been performed for the geometric optimized structures. As a final stage, real sample analyses have successfully been performed by using HMAC, as well as ICP–OES method. The relative standard deviation for copper (II) in mineral and drinking water samples has been determined to be below 0.15% and recovery values are in the range of 95.48–109.20%.
26 citations
TL;DR: The synthesized carbon dots have the advantages of simple manipulation, low cost and the high fluorescence quantum yield of them, and the detection limit of mercury (II) is as low as 0.41 μM.
Abstract: In this paper, we present a new method for the detection of mercury (II) and glutathione using carbon dots as fluorescent sensor. The synthesized carbon dots have the advantages of simple manipulation, low cost and the high fluorescence quantum yield of them which was22.79%. The combination of mercury (II) and carbon dots caused the turn off of carbon dots fluorescence. With the reaction between mercury (II) and glutathione, the carbon dots were released and the fluorescence was turned on when the glutathione added. According to this, the carbon dots could be developed to detect mercury (II) and glutathione specifically, and the detection limit of mercury (II) is as low as 0.41 μM.
TL;DR: Pyrimidine derivative Schiff base ligand (DPMC) stabilized metal nanoparticles of copper and nickel were synthesized by modified Brust-Schiffrin technique, which is a two-step phase transfer assisted synthesis.
Abstract: Pyrimidine derivative Schiff base ligand (DPMC) stabilized metal nanoparticles of copper (DPMC-CuNPs) and nickel (DPMC-NiNPs) were synthesized by modified Brust-Schiffrin technique, which is a two-step phase transfer assisted synthesis. The prepared metal nanoparticles were confirmed by UV-Visible and Infrared spectroscopy. The size, surface morphology and the quality of the DPMC and its MNPs were analyzed by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) methods respectively. Electrochemical behavior of the DPMC-CuNPs and DPMC-NiNPs was analyzed by cyclic voltammetry method. DNA binding studies of the synthesized compounds with CT-DNA were examined by four different techniques such as UV-Visible and emission spectroscopy, cyclic voltametry and viscometric measurments. Thermal denaturation and sono-chemical denaturation studies of DNA with the DPMC, DPMC-CuNPs and DPMC-NiNPs results also suggest the synthesized compounds have good DNA binding ability. Various antioxidant scavenging studies results shows that DPMC and its copper and nickel nanoparticles have significant antioxidant activity. Antimicrobial studies of the DPMC and its MNPs were studied by Agar-Agar well diffusion method. Anticancer studies of the DPMC and its MNPs show that the DPMC-CuNPs and DPMC-NiNPs have significant anticancer activity with least toxicity than the standard drug cis-platin. Graphical Abstract.
TL;DR: The synthesized ZnO/SiO2 core/shell nanoparticle shows high cell viability, hemocompatibility and promising florescent property and was synthesised by wet chemical method for fluorescent probing and drug delivery application.
Abstract: Semiconducting nanoparticles with luminescent properties are used as detection probes and drug carriers in in-vitro and in-vivo analysis. ZnO nanoparticles, due to its biocompatibility and low cost, have shown potential application in bioimaging and drug delivery. Thus, ZnO/SiO2 core/shell nanoparticle was synthesised by wet chemical method for fluorescent probing and drug delivery application. The synthesised core/shell nanomaterial was characterized using XRD, FTIR, UV-VIS spectroscopy, Raman spectroscopy, TEM and PL analysis. The silicon shell enhances the photoluminescence and aqueous stability of the pure ZnO nanoparticles. The porous surface of the shell acts as a carrier for sustained release of curcumin. The synthesized core/shell particle shows high cell viability, hemocompatibility and promising florescent property. Graphical Abstract.
TL;DR: The present article reports the efficiency of L-cysteine modulated copper nanoclusters as a fluorescent probe for the selective determination of naturally occurring bile pigments biliverdin (BVD) and bilirubin (BLR).
Abstract: The present article reports the efficiency of L-cysteine modulated copper nanoclusters (L-cys-CuNCs) as a fluorescent probe for the selective determination of naturally occurring bile pigments biliverdin (BVD) and bilirubin (BLR). These pigments were found to quench the fluorescence of L-cys-CuNCs through static processes. Under optimized conditions, the proposed strategy permitted the quantification of BVD and BLR in the range 4.00 × 10−5 to 5.00 × 10−7M and 1.00×10−5 to 1.00×10−6 M respectively with limits of detection 2.33 × 10−7M and 2.29 × 10−7 M. The practical utility of the developed sensor have been investigated in spiked blood and urine samples.
TL;DR: A novel fluorescence chemosensor XYQ showed fluorescence turn-on to Zn(II) with high sensitivity and selectivity in aqueous media among 19 metal ions, possibly explained as a chelation-enhanced fluorescence (CHEF) effect with theoretical calculations.
Abstract: A novel fluorescence chemosensor XYQ for detecting Zn(II) was synthesized. XYQ showed fluorescence turn-on to Zn(II) with high sensitivity and selectivity in aqueous media among 19 metal ions. Its binding structure was demonstrated by ESI-MS, Job plot, and 1H NMR titration. The detection limit of XYQ to Zn(II) was 0.53 μM. It is much below WHO drinking water standard (76.0 μM). XYQ could be applied successfully to the test kit and real samples. The fluorescence turn-on process was possibly explained as a chelation-enhanced fluorescence (CHEF) effect with theoretical calculations.
TL;DR: An adept, rapid and novel water-soluble glutathione functionalized CdS quantum dots (GSH@CdS QDs) were fabricated using green pathway for sensing of heavy metal contamination prevalent in industrial wastewater as discussed by the authors.
Abstract: An adept, rapid and novel water-soluble glutathione functionalized CdS quantum dots (GSH@CdS QDs) were fabricated using green pathway for sensing of heavy metal contamination prevalent in industrial wastewater. GSH@CdS QDs were facilely synthesized in an aqueous phase reaction and were effectively characterized using FT-IR, XRD, FESEM, HRTEM and EDX techniques. The distinct fluorescence characteristics of GSH@CdS QDs were explored and the QDs showed selective sensitivity towards mercury ions with a low limit of detection of 0.54 nM under optimal conditions. The detailed interaction between GSH@CdS QDs and Hg2+ and the probable fluorescence quenching mechanism were established in this study. In comparison to already reported fluorescent probes, GSH@CdS QDs showed high sensitivity, biocompatibility, long fluorescence stability and convenient removal of mercury ions.
TL;DR: Upon the addition of Ca 2+, the fluorescence of OTC could be significantly enhanced with rapid response and high sensitivity, and achieved a good limit of detection as low as 125 nM in aqueous solution.
Abstract: Herein, we report an interesting finding about the new application of oxytetracycline (OTC), as a fluorescent probe for the detection of calcium ion (Ca2+), which proved that it can offer an expeditious, highly sensitive, and selective detection method for Ca2+. Upon the addition of Ca2+, the fluorescence of OTC could be significantly enhanced with rapid response and high sensitivity, and achieved a good limit of detection as low as 125 nM in aqueous solution. The complex formed via Ca2+ coordinating to the hydroxyl group of OTC contributes to the fluorescence enhancement, which has been proved by several characterization methods including UV-vis analysis, binding constant determination, and fluorescence titration. The method avoided complexity for EDTA measurement of Ca2+ in running water as proposed previously. Taking advantage of good availability, stability and operability, the OTC was further successfully applied to the detection of Ca2+ in a real environment.
TL;DR: Some of synthesized porphyrins are found to be photostable and competent to discover as PDT agents as compared to reference H 2 TPP.
Abstract: New porphyrin analogues have been designed and synthesized using pyrrole, various aldehydes and propionic acid. The formation of desired compounds was analyzed by utilizing the spectral analysis such as IR, NMR and Mass spectroscopy. The studies on absorption and fluorescence emission of synthesized porphyrins were used to evaluate photophysical characteristics such as molar excitation coefficient and Stokes shift. The estimated values of fluorescence lifetime and fluorescence quantum yield of synthesized porphyrins were found to be variable due to the presence of change in the electron donating and withdrawing characters. The efficiency of generation of singlet oxygen by each synthesized porphyrin as photosensitizer was measured in terms of singlet oxygen quantum yield through photooxidation of 9,10-dimethylantharacene. The obtained singlet oxygen quantum yield values were found to be higher in case of porphyrins those have more electron withdrawing characters rather than donating characters as compared to reference 5,10,15,20-tetraphenylporphyrin (H2TPP). The singlet oxygen quantum yield values of synthesized porphyrins varied from 0.52 to 0.66. Pleasingly, some of synthesized porphyrins are found to be photostable and competent to discover as PDT agents as compared to reference H2TPP.
TL;DR: These features provide potential uses of BODIPY functionalized magnetite fluorescent nano-sensors (Fe 3 O 4 @SiO 2 -TPED-BodIPY and Fe 3 O 2 -TMPTA-BODIPy) as a new class of non-toxic sensors for environmental applications.
Abstract: In this study, we developed two different very sensitive magnetite fluorescent Fe3O4@SiO2-TPED-BODIPY and Fe3O4@SiO2-TMPTA-BODIPY nano-sensors for the selective detection of Cr(VI) ions. The Cr(VI) metal ions sensing is based on the fluorescent quenching of BODIPY functionalized with Fe3O4@SiO2-TPED and Fe3O4@SiO2-TMPTA nanoparticles in the ethanol-water environment. Characterization of the newly synthesized fluorescent BODIPY compound was performed on a 1H and 13C-NMR spectrometer. The morphology, chemical and physical properties of the sensing nano-sensors were studied by transmission thermogravimetric analysis (TGA), X-ray diffraction (XRD), energy dispersive X-ray (EDX), scanning electron microscopy (SEM), FT-IR spectroscopy, and transmission electron microscopy (TEM). UV-visible and fluorescent spectroscopy were used to characterize BODIPY functionalized magnetite fluorescent nano-sensors. Characterization measurements revealed that the mean particle diameter of magnetite fluorescent Fe3O4@SiO2-TPED-BODIPY and Fe3O4@SiO2-TMPTA-BODIPY nano-sensors was 18.5 and 19 nm, respectively. The magnetite fluorescent Fe3O4@SiO2-TPED-BODIPY and Fe3O4@SiO2-TMPTA-BODIPY nano-sensors (0.1 gL−1 in EtOH/H2O, v/v (3/7)) showed fluorescence quenching responses towards Cr(VI) ions in the medium at pH:1. The fluorescence quenches of the magnetite fluorescent Fe3O4@SiO2-TPED-BODIPY and Fe3O4@SiO2-TMPTA-BODIPY nano-sensors by Cr(VI) were completed in first 5 and 3 min. Respectively. These features provide potential uses of BODIPY functionalized magnetite fluorescent nano-sensors (Fe3O4@SiO2-TPED-BODIPY and Fe3O4@SiO2-TMPTA-BODIPY) as a new class of non-toxic sensors for environmental applications.
TL;DR: This novel ICT-based fluorescent ON-OFF-ON fluorescent probe successfully applied in the living cells for the detection of Cu2+ and H2S and shows a very fast response to Cu2- (within 10 s), its response to copper ion could be reversed by H1S.
Abstract: Copper ion plays an important role in many biological processes in human body. H2S is considered as the third gasses transmitter after carbon monoxide and nitric oxide. Here a novel ICT-based fluorescent ON-OFF-ON probe for Cu2+ and H2S detection was developed. Selectivity and sensitivity of probe was confirmed in aqueous Tris-HCl buffer (10 mM, pH 7.4, containing 90% acetonitrile). Probe DF-CU shows high selectivity over other analytes. The degree of fluorescence quenching is linearly associated with the concentration of Cu2+ (R2 = 0.9919). The limit of detection (LOD, calculated according to the 3σ/slope) for Cu2+ was 6.4 μM. Probe can work in almost all pH. The probe shows a very fast response to Cu2+ (within 10 s). Its response to copper ion could be reversed by H2S. The complex of probe with Cu2+ could be used for H2S detection. Furthermore, this ON-OFF-ON fluorescent probe successfully applied in the living cells for the detection of Cu2+ and H2S.
TL;DR: Responsiveness of sensing materials 3-hydroxyflavone (3HF) towards metal ions in aqueous medium has been explored following photoexcitation and the proposed simple, quick response and visual test strip-based chemosensor could be used for the detection of Fe 2+ and Cu 2+ ions.
Abstract: Responsiveness of sensing materials 3-hydroxyflavone (3HF) towards metal ions in aqueous medium has been explored following photoexcitation. 3HF exhibited both colorimetric and fluorescence (FL) turn–off response towards Cu2+ and Fe2+ with high sensitivity and selectivity. Meanwhile, the distinct colour change and the rapid quenching of FL intensity provide naked-eye detection. On successive addition of Cu2+and Fe2+ ions, FL of 3HF was “turned off,” whereas there is no change in wavelength of FL bands. Quenching efficiencies for Cu2+and Fe2+ ions are 88% and 49%, respectively. The detection limit of the sensor towards Cu2+ and Fe2+ was 1.54 μM and 1.98 μM, respectively. The binding strategy between 3HF and metal ions (Cu2+, Fe2+) and the nature of quenching have been explored with the Benesi-Hildebrand and Stern-Volmer plots, respectively. The FL of 3HF significantly quenched in the presence of Cu2+ ions, and then recovered upon addition of HCl, providing the possibility of constructing a sensitive Cu2+-HCl off-on fluorescent probe. Moreover, the proposed simple, quick response and visual test strip-based chemosensor could be used for the detection of Fe2+ and Cu2+ ions.
TL;DR: A new and novel hydrazone based dual-responsive ratiometric/colorimetric chemosensor have been developed for highly selective and sensitive detection of Cu2+ and F− ions in dimethyl sulfoxide (DMSO) solvent.
Abstract: Colorimetric sensors have attracted wide scope of attentions due to its fascinating advantages, like handy, equipment-free and naked eye detections. In this investigation, a new and novel hydrazone based dual-responsive ratiometric/colorimetric chemosensor have been developed for highly selective and sensitive detection of Cu2+ and F− ions in dimethyl sulfoxide (DMSO) solvent. The probe showed highly selective sensing towards Cu2+ and F− ions by exhibiting a color change from pale yellow to yellowish green and pale yellow to yellowish brown respectively., in DMSO without any interference of other ions at same concentration. These experimental results have also substantiated by the NMR, HR-MS, UV-Vis spectroscopic, cyclic voltammetry, differential pulse voltammetry techniques and DFT calculations. The detection limits are found to be 5.8 μM for Cu2+ and 0.025 μM for F− ions which is far below to the values recommended by WHO. The stoichiometric ratios between NAPCBH and Cu2+/ F- ions were confirmed from the Job’s plots and 1H NMR titration experiments which are found to be 2:1 and 1:1 respectively. The tracking ability of the DNA with NAPCBH-Cu2+ was studied by UV-Vis titration and Cyclic voltammetry measurements. It shows efficient affinity towards DNA with NAPCBH-Cu2+. The probe can also quantitatively determine the Copper and fluoride ions present in environmental samples & toothpaste. The NAPCBH was promptly recovered by utilizing very low concentration of HCl, showing that was found feasible and re-usable sensor for the convenient detection of Cu2+ and F− ions.
TL;DR: A new conjugated polymer possessing calixarene-oxacyclophane units wired-in-series by phenyleneethynylene linkers was synthesized by a Sonogashira-Hagihara cross-coupling method in high yield and a high sensitive response was observed in the detection of nitroaromatics and nitroanilines in neat vapour phases by casted films of the polymer.
Abstract: A new conjugated polymer possessing calix[4]arene-oxacyclophane units wired-in-series by phenyleneethynylene linkers was synthesized by a Sonogashira-Hagihara cross-coupling method in high yield. The polymer was structurally characterized by FTIR and 1H/13C/HSQC NMR techniques, and its average Mn (38.5 kDa) retrieved from GPC analysis. The polymer is highly emissive (ΦF = 0.55) and exhibits a longer-than-usual excited-state lifetime (1.80 ns) for a phenyleneethynylene type polymer. Similar photophysical properties (absorption and fluorescence emission) were observed in solution and in solid-state. This stems from the presence of bulky calixarene moieties along the polymer chains which prevent interchain staking and the formation of ground-state aggregates and/or non-emissive exciplexes, both deleterious to solid-state materials envisioned for fluorescence sensing applications. Moreover, the intrinsic molecular recognition capabilities of its two rigid inner cavities (calixarene and cyclophane sub-units), allied with the high three-dimensionality of the macromolecule that creates additional interstitial voids around the molecular receptors, can boost its sensory responses towards specific analytes. A high sensitive response was observed in the detection of nitroaromatics and nitroanilines in neat vapour phases by casted films of the polymer. The largest sensitivities were obtained for 2,4-dinitrotoluene (a taggant for the explosive TNT; > 85% of fluorescence quenching upon 1 min exposure) and ortho-nitroaniline (90% of emission reduction in 30 s). The sensory responses attained in solid-state are discussed on the basis of the electron affinities of the analytes and their electrostatic interactions with polymer films.
TL;DR: The results showed that the ball milling assisted hydrothermal method can synthesis of useful carbon nanomaterials with high photoluminescence intensity, highly photocatalytic activity and surface adsorption via a simple and fast method with the pine fruit.
Abstract: To green synthesis of highly yield photoluminescence carbon nanofibers/carbon quantum dots by pine fruit the ball milling assisted hydrothermal method was served. Different analysis such as XRD, EDS, elemental mapping and FT-IR analysis were used to study the product structure. The optical properties of the synthesized carbon nanomaterials were investigated by UV-Vis and PL analysis. Also, the effects of hydrothermal time and temperature on the PL intensity were studied. To study the product size and morphology SEM and TEM analysis were served. Also, the nucleation and growth mechanism was studied by TEM images. The results showed the product is composed of very tiny nitrogen-doped carbon dots and carbon nanofibers with high photoluminescence intensity. The photocatalytic activity of the product was investigated by degradation of six dyes namely Acid blue, Eosin Y, Erichrome Black T, Methylene blue, Methyl orange and Methyl. The results showed the product has high photocatalytic activity and it can degrade the dyes with creation reactive oxide species in the aqueous solution. The surface activity of the product was also investigated and it was found it can adsorb Pb2+ and Cd2+ from the water with 100% efficiency. The results showed we can synthesis of useful carbon nanomaterials with high photoluminescence intensity, highly photocatalytic activity and surface adsorption via a simple and fast method with the pine fruit. Graphical abstract.
TL;DR: The results of this study indicated that the validation method based on fluorimetry which was developed here is reliable for the detection of CUR in liposomal formulations and plasma.
Abstract: In this paper, we have reported a rapid, simple, sensitive, straightforward, and validated method for the concentration determination of curcumin (CUR) in nanoliposomes and plasma using the spectrofluorimetry. For both nanoliposomal formulation and plasma, methanol was used as a solvent to extract the CUR. The excitation and emission wavelengths were set at 423 nm and 527 nm, respectively. The method validation was performed based on International Council for Harmonization (ICH) guidelines, Q2, in which parameters; such as, linearity, precision, accuracy and etc., were determined. The results showed that the calibration curve was linear for CUR concentrations of 0.05 to 0.5 μg /mL with a correlation coefficient of 0.9996. The limit of detection (LOD) and limit of quantification (LOQ) were 0.03 and 0.10 μg/mL, respectively. Liposomal CUR (15 mg/kg) was injected intravenously to mice, and at certain time intervals (1, 3, 6, and 24 h), blood samples were collected. The samples were extracted by methanol and CUR concentrations were detected using a fluorescence spectrophotometer. Results indicated the rate of liposomal formulation decline was slower than free CUR. The results of this study indicated that the validation method based on fluorimetry which was developed here is reliable for the detection of CUR in liposomal formulations and plasma.
TL;DR: The acid-base reversibility character of the probe was investigated as well as the effect of the pH change on the fluorescence quantum yield, and the application of the prepared BFFPH probe for detection of living Escherichia coli bacteria using confocal fluorescence microscope was investigated.
Abstract: A new turn on fluorescence probe based on 3′,6′-dihydroxy-6-methyl-2-((pyridin-2-ylmethylene)amino)-4-(p-tolyl)spiro[benzo[f]isoindole-1,9′-xanthen]-3(2H)-one (BFFPH) derived from benzo[f]fluorescein was prepared. Full characterization of the prepared probe using spectroscopic analysis was described such as IR, NMR and MS spectra. The sensitivity of BFFPH for monitoring of pH change in alkaline medium was studied. BFFPH exhibited a high sensitivity to alkaline pH by two pKa values at 8.82 and 10.66 in UV/vis spectroscopy titration. The pH monitoring was studied in broad range of pH values (2.5–12.2) at two pKa values at 8.72 and 10.73 by recording the effect of pH on the fluorescence intensity of BFFPH. The acid-base reversibility character of the probe was investigated as well as the effect of the pH change on the fluorescence quantum yield. The application of the prepared BFFPH probe for detection of living Escherichia coli (E. coli) bacteria using confocal fluorescence microscope was investigated.
TL;DR: HHPBA-BODIPY proved efficient to detect Cu2- in water samples which offers the possibility to detect trace amount of Cu2+ for environmental monitoring and is also selective toward Cu2+, while other metal ions show no interfere.
Abstract: Based on boron-dipyrromethene (BODIPY), taking 2-hydroxy-N-(2-hydroxyphenyl)benzamide as recognition site, a new fluorescent probe HHPBA-BODIPY aimed at sensitively detecting Cu ions was designed, synthesized and characterized.The emission spectra of HHPBA-BODIPY exhibited an intensive green fluorescence around 510 nm, with a maximum absorption near 500 nm. When Cu2+ ions are present, the fluorescence at 510 nm can be quenched with a good linearity between the copper ion concentrationand the fluorescence intensity and the detection limit is 0.35 μM. HHPBA-BODIPY is also selective toward Cu2+, while other metal ions show no interfere except Fe3+ and Cr3+ ions. In addition, HHPBA-BODIPY also proved efficient to detect Cu2+ in water samples which offers the possibility to detect trace amount of Cu2+ for environmental monitoring. Copper ions; BODIPY; fluorescent probe.
TL;DR: Ic could serve as a high-efficiency and low-cost fluorescent probe for tracking Ag+ in an aquatic environment and biological organisms and could be a useful tool for the environmental monitoring of Ag+ pollution.
Abstract: In this study, an imidazole-coumarin based fluorescent probe was developed for the selective and sensitive detection of Ag+ in aqueous solution. Using a combination of Job plot, NMR titrations, and DFT calculations, the binding properties between Ag+ and the probe were deeply investigated, and the results revealed a 1:1 binding stoichiometry between the probe and Ag+ with a binding constant of 1.02 × 106 M−1. The detection limit was found to be 150 nM, which satisfies the requirement for the quantitative detection of Ag+ in real water samples. Moreover, the new probe, Ic, was successfully applied to sense Ag+ in HeLa and HepG2 cells as well as in C. elegans, indicating that it could be a useful tool for the environmental monitoring of Ag+ pollution. These results demonstrated that Ic could serve as a high-efficiency and low-cost fluorescent probe for tracking Ag+ in an aquatic environment and biological organisms.
TL;DR: In this article, a low power continuous wave (CW) diode laser working at 635nm wavelength was used to perform the Z-scan experiments in the present study, where acid blue 3 (AB 3) dye was dissolved with different polar solvents of 1-propanol, ethanol, dimethyl sulfonate (DMSO) and water at a concentration of 0.01mM.
Abstract: The polar solvents dependent linear and third-order nonlinear optical (NLO) characteristics of acid blue 3 (AB 3) dye has been reported in this paper. A low power continuous wave (CW) diode laser working at 635 nm wavelength was used to perform the Z-scan experiments in the present study. AB 3 dye was dissolved with different polar solvents of 1-propanol, ethanol, dimethyl sulfonate (DMSO) and water at a concentration of 0.01 mM. The nonlinear index of refraction (n2) of AB 3 dye was ascribed to self-defocusing effect, and nonlinear coefficient of absorption (β) signifies the behaviors of saturable and reverse saturable absorption. The real and imaginary components of the third-order NLO susceptibility of AB 3 dye in the present polar solvents have been measured to be of the order of 10─6 esu. The influence of polar solvents on third-order NLO susceptibility of the dye sample studied has been discussed. The second-order hyperpolarizability (γ) of AB 3 dye has also been studied and estimated to be of the order of 10─30 esu. The experimental results suggest that AB 3 dye may be a promising candidate for applications in nonlinear optics.
TL;DR: This “turn-on” fluorescence can be used to detect both or either environmental and physiological contaminants mercury and thiocyanate and could prove useful for the development of simple point-of-care diagnostics in the future.
Abstract: In this work, 1.8 nm graphene quantum dots (GQDs), exhibiting bright blue fluorescence, were prepared using a bottom-up synthesis from citric acid. The fluorescence of the GQDs could be almost completely quenched (about 96%) by adding Hg2+. Quenching was far less efficient with other similar heavy metals, Tl+, Pb2+ and Bi3+. Fluorescence could be near quantitatively restored through the introduction of thiocyanate. This “turn-on” fluorescence can thus be used to detect both or either environmental and physiological contaminants mercury and thiocyanate and could prove useful for the development of simple point-of-care diagnostics in the future.