Fluorescence Sensor For Detection Research Articles

Boric acid and Schiff base-based fluorescent sensor for detection of L-tryptophan in milk and BSA samples.

In the present paper, the fluorescence sensor based on Schiff base and boric acid was developed for easy and rapid detection of L-tryptophan in different samples such as milk and bovine serum albumin. The photoluminescence intensity was measured by using fluorescent measurements and the results indicated that the developed fluorescent sensor was exhibited selective, sensitive, reliable determination against L-tryptophan, and a series of various analytes such as cations, amino acids, and organic compounds were used to investigate the selectivity of the fluorescent chemosensor. The limit of detection and linear range of the chemosensor were calculated as 0.82 μM, and 0.1-500 μM, respectively. The performance of the chemosensor was evaluated in terms of selectivity, reversible usage, stability, and interference/anti-interference. The developed chemosensor was exhibited excellent photostability, and it was a great potential application of L-tryptophan in bovine serum albumin and milk samples.

A ratiometric fluorescent sensor for detection of metformin based on terbium-1,10-phenanthroline-nitrogen-doped-graphene quantum dots.

Metformin (MTF), an effective biguanide and oral antihyperglycemic agent, is utilized to control blood glucose levels in patients with type II diabetes mellitus, and the determination of its concentration in biological fluids is one of the main issues in pharmacology and medicine. In this work, highly luminescent nitrogen-doped graphene quantum dots (N-GQDs) were modified using terbium (Tb3+)–1,10-phenanthroline (Phen) nanoparticles (NPs) to develop a dual-emission ratiometric fluorescent sensor for the determination of MTF in biological samples. The synthesized N-GQDs/Tb–Phen NPs were characterized using different techniques to confirm their physicochemical properties. The N-GQDs/Tb–Phen NPs showed two characteristic emission peaks at 450 nm and 630 nm by exciting at 340 nm that belong to N-GQDs and Tb–Phen NPs, respectively. The results indicated that the emission intensity of both N-GQDs and Tb–Phen NPs enhanced upon interaction with MTF in a concentration-dependent manner. Also, a good linear correlation between the enhanced fluorescence intensity of the system and MTF concentration was observed in the range of 1.0 nM–7.0 μM and the limit of detection (LOD) value obtained was 0.76 nM. In addition, the prepared probe was successfully used for the estimation of MTF concentration in spiked human serum samples. In conclusion, the reported dual-emission ratiometric fluorescent sensor can be used as a sensitive and simple fluorimetric method for the detection of MTF in real samples.

Carboxyl-Rich Carbon Dots as Highly Selective and Sensitive Fluorescent Sensor for Detection of Fe3+ in Water and Lactoferrin.

As lactoferrin (LF) plays an essential role in physiological processes, the detection of LF has attracted increasing attention in the field of disease diagnosis. However, most current methods require expensive equipment, laborious pretreatment, and long processing time. In this work, carboxyl-rich carbon dots (COOH-CDs) were facilely prepared through a one-step, low-cost hydrothermal process with tartaric acid as the precursor. The COOH-CDs had abundant carboxyl on the surface and showed strong blue emission. Moreover, COOH-CDs were used as a fluorescent sensor toward Fe3+ and showed high selectivity for Fe3+ with the limit of detection (LoD) of 3.18 nM. Density functional theory (DFT) calculations were performed to reveal the mechanism of excellent performance for Fe3+ detection. Meanwhile, COOH-CDs showed no obvious effect on lactobacillus plantarum growth, which means that COOH-CDs have good biocompatibility. Due to the nontoxicity and excellent detection performance for Fe3+, COOH-CDs were employed as a fluorescent sensor toward LF and showed satisfying performance with an LoD of 0.776 µg/mL, which was better than those of the other methods.

Water-stable europium(III) and terbium(III)-metal organic frameworks as fluorescent sensors to detect ions, antibiotics and pesticides in aqueous solutions

The reliable, convenient and rapid detection methods for various environmental pollutants using fluorescent sensors had attracted great attention. Herein, we reported the assembly and characterizations of two new fluorescent 3D lanthanide metal-organic frameworks (Ln-MOFs), namely [Eu(PMBB)1.5(H2O)2] (Eu-MOF) and [Tb(PMBB)1.5(H2O)2] (Tb-MOF) (H2PMBB = 4,4′-((1,4-phenylenebis(methylene))bis(oxy))dibenzoic acid). The fluorescent sensing results reveal that the two MOFs exhibit effective sensitivity toward Fe3+, Cr2O72−, cefixime (CFX), nitrofurazone (NFZ), imidacloprid (IMI) and nitenpyram (NTP) in aqueous medium. Notably, the Tb-MOF is more sensitive toward MnO4− than Eu-MOF due to the enhanced fluorescence resonance energy transfer (FRET) effect. This work provides the example for more effective designs to employ Ln-MOFs as fluorescent sensors for detection of environmental pollutants in aqueous solution.

Sensitively liquid and gaseous detection of formaldehyde based on a supramolecular organic framework

Because of the serious threat to human health, the development of fluorescent sensor for detection of formaldehyde (FA) has attracted great concern. Herein, a 4,4′-(1,2-diphenylethene-1,2-diyl)dibenzoic acid-based SOF (HNU-44), has been assembled, which can be used to detect FA by quite different fluorescent response in liquid and gas. In liquid phase, HNU-44 exhibits fluorescence enhancement with the limit of detection (LOD) 27.41 ppb. On the contrary, fluorescence quenching happens when HNU-44 is exposed in the FA atmosphere with the LOD of 2.61 ppb. The LOD in gas is even lower than the air quality criterion of gaseous FA (80 ppb) recommended by World Health Organization (WHO). Furthermore, sensing tests were performed on fish samples, which means that HNU-44 can be used in actual sample. This work expands promising approach for effective FA detection both in the experiment test and actual application.

Repurposing the domestic organic waste into green emissive carbon dots and carbonized adsorbent: A sustainable zero waste process for metal sensing and dye sequestration

This work reports a one pot facile route for complete valorization of domestic organic waste into biogenic carbon dots (BCDs) and biochar for application as nanosensor and adsorbent respectively. Among the various precursors used, dried rose petals derived (BCDRP) and ripe banana peel derived (BCDBP) carbon dots demonstrated quantum yields comparable to other previously reported biomass derived green fluorescing carbon dots. The BCDs exhibited sizes < 10 nm and excellent photo-stability upto 30 days with respect to different irradiation times as well as ionic strength. The BCDs were assessed for their optical performance and employed as fluorescent sensor for detection of heavy metal ions. The semi-quantitative and quantitative studies shows that BCDRP was selective towards Cr6+ whereas BCDBP detected Fe3+ in a mixture of metal ions. LOD values in pM range (81 pM for Cr6+ in presence of BCDRP and 121 pM for Fe3+ in presence of BCDBP) advocates their high sensitivity. The real sample analyzing potential of the BCDs with excellent recoveries and minimal RSD suggest their successful practical applicability. For circular economy, the biochar formed as a byproduct was reused as an adsorbent for removal of cationic and anionic dyes with > 90% removal efficiencies. This protocol ensures a complete repurposing of organic waste into modified materials via a zero waste process as demonstrated by its schematic life cycle inventory chart.

Leftover Kiwi Fruit Peel-Derived Carbon Dots as a Highly Selective Fluorescent Sensor for Detection of Ferric Ion

Recently, the use of natural products for the synthesis of carbon dots (CDs) has received much attention. Herein, leftover kiwi (Actinidia Deliciosa) fruit peels were successfully turned into beneficial fluorescent carbon dots (KN-CDs) via the hydrothermal-carbonization route. KN-CDs 1 and KN-CDs 2 were prepared without and with ammonium hydroxide, respectively. KN-CDs 1 and KN-CDs 2 were systematically characterized by various analytical techniques. Synthesized KN-CDs showed spherical-shaped morphology with narrow size distribution and excellent optical properties with excitation-independent behaviors. The quantum yields of KN-CDs 1 and KN-CDs 2 were calculated as 14 and 19%, respectively. Additionally, the KN-CDs possess excellent prolonging and photostability. Because of the excellent optical properties of KN-CDs, they were utilized as fluorescent sensors. The strong fluorescence of the KN-CDs was selectively quenched by Fe3+ ion, and quenching behavior showed a linear correlation with the concentrations of Fe3+ ion. KN-CDs 1 and KN-CDs 2 showed the detection of Fe3+ ions within the concentration range of 5–25 µM with the detection limit of 0.95 and 0.85 µM, respectively. Based on the turn-off sensing by the detection of Fe3+ ions, KN-CDs would be a promising candidate as a selective and sensitive fluorescent sensor.

Quantitative Analysis of Fluorescence Detection Using a Smartphone Camera for a PCR Chip

Most existing commercial real-time polymerase chain reaction (RT-PCR) instruments are bulky because they contain expensive fluorescent detection sensors or complex optical structures. In this paper, we propose an RT-PCR system using a camera module for smartphones that is an ultra small, high-performance and low-cost sensor for fluorescence detection. The proposed system provides stable DNA amplification. A quantitative analysis of fluorescence intensity changes shows the camera’s performance compared with that of commercial instruments. Changes in the performance between the experiments and the sets were also observed based on the threshold cycle values in a commercial RT-PCR system. The overall difference in the measured threshold cycles between the commercial system and the proposed camera was only 0.76 cycles, verifying the performance of the proposed system. The set calibration even reduced the difference to 0.41 cycles, which was less than the experimental variation in the commercial system, and there was no difference in performance.

Polyhedral oligosilsesquioxane tethered tetraphenylethylene as turn-on fluorescent sensor for fluoride ions detection

A novel tetraphenylethylene derivative tethered with polyhedral oligosilsesquioxane nanocages (TPE-POSS) was designed and synthesized as turn-on fluorescent sensor for detection of F−. The aggregation-induced emission (AIE) property, self-assembly behavior and detection mechanism of the complex were then elucidated by UV–vis absorption spectra, photoluminescence spectra and dynamic light scattering experiments. The results reveal that POSS nanocages can collapse due to the Si–O bond cleavage with the present of F−. The POSS nanocages collapse then trigger the AIE activity of TPE luminogens, endowing TPE-POSS with excellent turn-on detecting ability, high selectivity and sensitivity to F−, with a detection limit as low as 1.66 × 10−7 M.

Fluorescent sensors for detection and quantification of bacterial siderophores and metal complexes

To proliferate in the host environment during colonization or infection, bacteria acquire iron from eukaryotic tissues, fluids, cells and proteins. To do so, they secrete siderophores that chelate iron, and they express membrane transporters that recognize and internalize ferric siderophores. The production of siderophores and the acquisition of ferric siderophores are determinants of microbial pathogenesis. For example, the E. coli outer membrane protein FepA actively transports ferric enterobactin, a prototypic catecholate iron complex of the Enterobacteriaceae, whose utilization promotes colonization of the mouse gut. We genetically engineered several fluorescent sensors to detect, discriminate and quantify ferric siderophores, in purified form or in complex mixtures of metabolites and other biochemicals. By substituting single Cys residues in TonB-dependent outer membrane transporters, and modifying them with maleimide fluorophores in living cells, we created sensors from different bacterial species that recognized different metal complexes: native, glucosylated, degraded ferric enterobactin; the hydroxamates ferric aerobactin, ferrichrome, ferric acinetobactin and ferrioxamine B: the porphyrins hemin and vitamin B12. In spectroscopic assays these constructs sensitively detected and quantified the different metal chelates in solution. These sensors facilitate assays of biochemical specificity, affinity, and membrane transport. They may also detect the presence and activities of bacterial pathogens, that often show a particular profile of siderophore production or ferric siderophore utilization. The sensors are useful for both basic research and drug discovery, because they rapidly detect and identifysiderophores in both clinical and food samples.

A magnetic functionalized lanthanide fluorescent sensor for detection of trace zinc ion

In this work, magnetic functionalized terbium coordination polymers (Fe3O4-GMP/Tb) as adsorbent were designed and prepared for Zn2+ detection through magnetic solid phase extraction. The morphology and structure of the as-prepared Fe3O4-GMP/Tb were characterized, which exhibited network structure incorporating magnetic Fe3O4 nanoparticles. The Fe3O4-GMP/Tb as magnetic adsorbents for magnetic solid phase extraction have possessed the merits of simple preparation, magnetic separation and without elution. The magnetic solid phase extraction method was studied for Zn2+ detection with magnetic separation and enrichment. The results showed that Fe3O4-GMP/Tb had possessed the strong enrichment ability (enrichment factor reached 29) and high sensitivity for Zn2+ due to their nanoscale size and the network structure incorporated Fe3O4. The as-prepared Fe3O4-GMP/Tb as adsorbent for the detection of Zn2+ have shown a wide liner range from 0 to 160 μM with detection limit of 0.21 μM. The as-prepared Fe3O4-GMP/Tb were also successfully used to monitor Zn2+ in living cells as fluorescent probe.

A fluorescent probe of uranyl for acid and high water system and imaging in living cells

Uranium mining, refining and spent fuel reprocessing are mostly carried out in an acidity and high water ratio environment. But there are currently fewer fluorescent probes that can meet this requirement. For this purpose, it is a urgent problem to design and synthesis fluorescent sensor for detection of uranium in these conditions. A novel triphenylamine-based fluorescent sensor (USC-001) has been design and prepared for the detection of uranyl ions in acidic and high water ratio environments and biologic samples. And even though the concentration of other metal ions is 5 times higher than that of uranyl ions, the probe is still have good selectivity to UO22+. In addition, a large number of auxiliary simulation calculations and experiment not only reveal the mechanism of the influence of water ratio on the change of the fluorescence spectrum, but also propose the mechanism and coordination mode of USC-001 for identifying UO22+. Furthermore, USC-001 has been successfully used to detect uranyl ions in actual water samples and biological cells.

Synthesis of novel lower rim dimethylcarbamodithioate substituted calix[4]arene as selective and sensitive turn-on fluorescent sensor for detection of phosphate in aqueous solution

In this study, we synthesized a novel sensitive and selective dimethylcarbamodithioate substituted calix[4]arene sensor DT2L for recognition PO43− among 20 various anions in CH3CN/H2O (99:1 v/v) solvent system. The structure of DT2L was determined by HRMS, 1HNMR, and 13CNMR. The properties of DT2L-phosphate complex were proven by fluorescence and NMR titration methods with a LOD of 7.9 nM, and binding constant 4 × 107 M−1.

Extraction and Application of Natural Rutin From Sophora japonica to Prepare the Novel Fluorescent Sensor for Detection of Copper Ions.

Rutin (R), a representative flavonoid found in various biomasses, can be used to prepare different fluorescent sensors for environmental, biological and medical fields. In this work, the natural R in Sophora japonica was extracted and purified to prepare fluorescent-responding sensor systems intended to recognize copper ions with both strong selectivity as well as appropriate sensitivity. Results showed that neat R had no obvious fluorescent emission peak in PBS buffer solution. However, when R and (2-hydroxypropyl)-β-cyclodextrin (CD) were introduced within buffer solution, fluorescent emission intensity was significantly increased due to the resultant R-CD inclusion complex. In addition, the formed R-CD inclusion complex was shown to behave as the aforementioned fluorescent sensor for copper ions through a mechanism of quenched fluorescent emission intensity when R-CD became bound with copper ions. The binding constant value for R-CD with copper ions was 1.33 × 106, allowing for quantification of copper ions between the concentration range of 1.0 × 10–7–4.2 × 10–6mol⋅L–1. Furthermore, the minimum detection limit was found to be 3.5 × 10–8mol⋅L–1. This work showed the prepared R-CD inclusion complex was both highly selective and strongly sensitive toward copper ions, indicating that this system could be applied into various fields where copper ions are of concern.

Two benzothiadiazole-based compounds as multifunctional fluorescent sensors for detection of organic amines and anions

Two benzothiadiazole-based compounds, namely 4,7-di(1H-1,2,4-triazol-1-yl)benzo-[2,1,3]thiadiazole (1) and 4,7-di(1H-pyrazol-1-yl)benzo-[2,1,3]thiadiazole (2), have been constructed with Cu-catalyzed cross-coupling reactions. The fluorescence studies show that compound 1 has high selectivity and sensitivity toward TEA (triethylamine), EDA (ethylenediamine), TMEDA (N,N,N’,N’-tetramethylethylenediamine), MnO4− and ClO− by fluorescence quenching, and compound 2 also has high selectivity and sensitivity toward TEA and TMEDA via fluorescence quenching. The calculated detection limits of 1 for TEA, EDA, TMEDA, MnO4− and ClO− are 0.129, 0.635, 0.320, 9.820 and 12.740 μM, respectively. Meanwhile, the detection limits of compound 2 for TEA and TMEDA are 0.400 and 0.278 μM, respectively. Interestingly, compounds 1 and 2 are the first fluorescent sensors for the selective recognition of TMEDA.

Fluorescence Sensors for Detection, Discrimination and Quantification of Siderophores

To proliferate in the host environment during colonization or infection, bacteria acquire iron from eukaryotic tissues, fluids, cells and proteins. To do so, they secrete siderophores that chelate iron, and they express membrane transporters that recognize and internalize ferric siderophores. The production of siderophores and the acquisition of ferric siderophores are determinants of microbial pathogenesis. For example, the E. coli outer membrane protein FepA actively transports ferric enterobactin, a prototypic catecholate iron complex of the Enterobacteriaceae, whose utilization promotes colonization of the mouse gut. We genetically engineered several fluorescent sensors to detect, discriminate and quantify ferric siderophores, in purified form or in complex mixtures of metabolites and other biochemicals. By substituting single Cys residues in TonB-dependent outer membrane transporters, and modifying them with maleimide fluorophores in living cells, we created sensors that recognized different metal complexes: native, glucosylated and degraded ferric enterobactin; the hydroxamates ferric aerobactin, ferrichrome and ferrioxamine B: the porphyrins hemin and vitamin B12. In spectroscopic assays these constructs sensitively detected and quantified the different metal chelates in solution. These sensors facilitate assays of biochemical specificity, affinity, and membrane transport. They may also detect the presence and activities of bacterial pathogens, that often show a particular profile of siderophore production or ferric siderophore utilization. The sensors are useful for both basic research and drug discovery, because they rapidly detect and identify siderophores in both clinical and food samples

A donor-π-acceptor aggregation-induced emission compound serving as a portable fluorescent sensor for detection and differentiation of methanol and ethanol in the gas phase

The design strategy of aggregation-induced emission (AIE) fluorophores with donor-π-acceptor (D-π-A) conjugation structure has greatly contributed to the development of luminescent materials and devices, including volatile organic compounds (VOCs) sensors. In this work, a D-π-A fluorophore DEBAB was synthesized, showing both AIE and intramolecular charge transfer (ICT) properties as confirmed by spectroscopic data and quantum chemical calculations. Furthermore, there is notable emission-enhancement when DEBAB is exposed to small-molecule alcohols, such as methanol and ethanol. Based on this phenomenon, a portable film sensor was fabricated, capable of detecting methanol and ethanol in gas phase, with detection limit (DL) as low as 8.02 ppm. Our systematic investigation suggests that hydrogen-bonding may be formed between DEBAB and alcohols, intensifying the AIE efficacy while influencing the ICT process. This working mechanism is supported by density functional theory (DFT) calculations including electrostatic potential mapping and molecular total energy. In addition, a sensor array was fabricated on a cellulose paper strip, showing different levels of emission changing in response to alcohols. Thus the detection and differentiation of methanol and ethanol are enabled.

Water-Stable Europium(III) and Terbium(III)–Metal Organic Frameworks as Fluorescent Sensors to Detect Inorganic Ions, Antibiotics and Pesticides in Aqueous Solutions

Development of reliable, convenient and rapid detection methods for environmental pollutants using fluorescent sensors has attracted great attention. Herein, we reported the assembly and characterizations of two new fluorescent 3D lanthanide metal-organic frameworks (Ln-MOFs), namely [Eu(PMBB)1.5(H2O)2] (Eu-MOF) and [Tb(PMBB)1.5(H2O)2] (Tb-MOF) (H2PMBB = 4,4'-((1,4-phenylenebis(methylene))bis(oxy))dibenzoic acid). The structural data veal that both of the structures constructed in 3D network, in view of topology, Eu-MOF is in a bnn net and Tb-MOF is in an mab net. The fluorescent sensing results revealed that the two MOFs exhibit effective sensitivity toward Fe3+, Cr2O72-, cefixime (CFX), nitrofurazone (NFZ), imidacloprid (IMI) and nitenpyram (NTP) in aqueous medium. Notably, the Tb-MOF is more sensitive toward MnO4- in fluorescent quenching tests than Eu-MOF due to the Forstert resonance energy transfer (FRET) effect. This work provides the first example to employ MOFs as fluorescent sensors for detection of IMI in aqueous solution.

A water-stable zinc(ii)–organic framework as an “on–off–on” fluorescent sensor for detection of Fe3+and reduced glutathione

A zinc(ii) metal–organic framework exhibits fluorescence on–off–on behaviour for Fe3+and reduced glutathione in PBS solution and in real samples.

RETRACTED: Two transition metal coordination polymers: Fluorescent sensing property and capability of treating neuropathic pain via regulating the ephrinBs-EphBs signaling pathway

Abstract By using a tripodal ether-connector tricarboxylic ligand 1,3,5-tris(carboxymethoxy)benzene (H3TCMB) as the organic linker, two new transition metal coordination polymers (CPs) were synthesized via reaction of Zn(NO3)2•6H2O or Co(NO3)2•6H2O with H3TCMB ligand under the solvothermal reaction conditions, and their chemical formulae are [Co3(TCMB)2(H2O)4]n•4nH2O (1) and [Zn3(TCMB)(μ3 OH)3]n•0.5nH2O (2). The single crystal X-ray diffraction study shows that complex 1 is a 2D layered network which is further extended into a 3D supramolecular network via H-bond interactions, and complex 2 shows a 2D layered structure based on a [Zn3(μ3 OH)3]n cluster-based unit. As expected, complex 2 displays excellent luminescence in the solid state and solution, and it could serve as an ultrasensitive fluorescent sensor for detection of 2,4,6-Trinitriphenol (PA). The therapeutic activity of these two compounds on neuropathic pain was evaluated. First, the expression levels of ephrinB receptor were detected via the real-time RT-PCR method, the results showed that ephrinB receptor expression levels in the sciatic nerve was significantly reduced by compound 1, but compound 2 did not show such effect. Then, the EphB ligand content was determined through the ELISA test, the results indicated that compound 1 was found more effective than compound 2 in reducing the content of EphB in the sciatic nerve.