Fluorescent Probe For Detection Research Articles

Semicarbazide-based fluorescent probe for detection of Cu2+ and formaldehyde in different channels

Two fluorescent sensors with the receptor semicarbazide respectively at 7- (CAA) and 3-position (CAB) of coumarin were designed and synthesized. CAA exhibits fluorescence turn-on response to Cu2+ by triggering the intramolecular charge transfer (ICT) process via Cu2+-catalyzed hydrolysis, and can detect formaldehyde (FA) at different channel by inhibiting the photo-induced electron transfer (PET). However, CAB displays quite different responses: the photophysical properties hardly changed in the presence of FA; while a three-stage fluorescence response of fast quenching, steady increasing and slowly decreasing was found upon addition of Cu2+. The high selectivity enabled CAA a good candidate for quantification of Cu2+ and formaldehyde as well as bioimaging Cu2+ in living cells. Good linear relationships between the fluorescence intensity and analyte concentration were observed in the range of 0.1–30 μM for Cu2+ and 1.0–50 μM for FA, and their detection limits (LOD) were calculated to be 0.43 μM and 1.92 μM (3δ/k), respectively.

Synthesis, characterization of 4,4′-((1E,1′E)-hydrazine-1,2-diylidenebis(methanylylidene)) diphenol and the inclusion complex with γ-cyclodextrin as a fluorescent probe for detection of Al3+

The 4, 4′- ((1E, 1′E)-hydrazine-1,2-diylidenebis(methanylylidene)) diphenol (4-HBA) is successfully synthesized utilizing 4-hydroxybenzaldehyde (4-HB) and hydrazine hydrate as the starting materials. The synthesized 4-HBA is confirmed by the spectral analysis of 1H NMR, FT-IR, UV–Visible, and HR-Mass spectroscopy. The inclusion complexes of 4-HBA with γ-cyclodextrin are therefore investigated using UV and fluorescence spectroscopy. When γ-CD combined with 4-HBA, a 1:1 inclusion complex (ICs) is created that causes absorption and fluorescence spectral changes. The molecular computational analysis is carried out utilizing PM3 Gaussian software revealing the orientation of the synthetic 4-HBA within the γ-CD cavity. The HOMO-LUMO band gap and the DFT analysis specifically support the ICs, with the help of energy values and the H-bond distance. The hydrophobic contact between the host and guest molecules is strongly supported by the 1H NMR and 2-D NMR data, with the matching Ar-H proton moving to higher chemical shift values and the strong cross-correlation spot validating the conclusion. Al3+ sensing activity is observed using fluorescent probes in conjunction with UV and FL spectral analysis. Other metal ions are present in the solutions even though they are not readily available, most notably the Al3+ that binds to the fluorescent probe. Here, the Al3+ selective responses, the colour changes at the wavelength regions, and a fluorescence microscopic image of the solution media are also shown. The selected metal ions recovery percentage is used to determine the concentrations in a variety of clean water samples, including tap water, pond water, and also sea water.

A "Turn-on" Fluorescent Probe Based on Phenothiazine for Selectively Recognizing ClO- and its Practical Applications.

Hypochlorous acid (HClO), a highly reactiveoxygen 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 = 0.472μM), fast response time (< 1min) and large Stokes shift (150nm) 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.

A coumarin-based small molecular fluorescent probe for detection of the freshness of meat and shrimp

A coumarin-based small molecular fluorescent probe for detection of the freshness of meat and shrimp

A unique ratiometric fluorescent probe for detection of SO2 derivatives in living cells and real food samples

Abnormal levels of SO2 in organisms can cause cardiovascular disease and respiratory allergies. In addition, the amount of SO2 derivatives used as food preservatives is strictly controlled, and excessive addition can also be harmful to health. Therefore, it is essential to develop a highly sensitive method for the detection of SO2 and its derivatives in biological systems and real food samples. In this work, a new fluorescent probe (TCMs) with high selectivity and sensitivity for the detection of SO2 derivatives was reported. The TCMs could quickly identify SO2 derivatives. It has been successfully used to detect exogenous and endogenous SO2 derivatives. Furthermore, the TCMs has high sensitivity to SO2 derivatives in food samples. Moreover, the prepared test strips could be evaluated for the content of SO2 derivatives in aqueous solutions. This work provides a potential chemical tool to detect SO2 derivatives in living cells and real food samples.

Synthesis of Nanocellulose‐Based Nitrogen‐Doped Carbon Quantum Dots with High Fluorescence Quantum Yields for Multifunctional Applications

AbstractCarbon quantum dots (CQDs) are one of the most promising luminescent nanomaterials for anti‐counterfeiting due to their excellent optical properties, low toxicity, and environmental friendliness. With the development of green chemistry, biomass carbon sources have attracted attention. Herein, nitrogen‐doped carbon quantum dots (N‐CQDs) are synthesized using waste corn bract nanocellulose as the carbon source and L‐histidine as the nitrogen source in a simple and quick one‐step microwave method. It is found that a raw material mass ratio of 1:4, a temperature of 100 °C, and a preparation time of 5 min are the optimum preparation conditions. The fluorescence quantum yield of N‐CQDs obtained under these conditions is 32.64%. Under the excitation of light at a wavelength of 365 nm, the emission peak of N‐CQDs is located at 430 nm and emits blue light. This study also provides a method to prepare fluorescent anti‐counterfeiting films with excellent performance and fluorescent detection probes solely from waste biomass corn bract leaves and L‐histidine.

A novel RhB@MOF-808 fluorescent probe for the rapid detection of dopamine and Fe3+

Dopamine (DA) and Fe3+ as the important bioactive ingredients, playing an indispensable role in human metabolism. Therefore, developing the accurate detection of DA and Fe3+ is of great significance for disease screening. Herein, we put forward a simple, rapid, and sensitive fluorescent detection strategy for the detection of dopamine and Fe3+ based on Rhodamine B-modified MOF-808 (RhB@MOF-808). RhB@MOF-808 produced strong fluorescence at 580 nm, and the fluorescence was significantly quenched after DA or Fe3+ was added, which was regarded as a static quenching process. Detection limits are as low as 60.25 nM and 48.34 nM, respectively. Furthermore, based on the responses of DA and Fe3+ to the probe, molecular logic gates were successfully designed. More importantly, RhB@MOF-808 had excellent cell membrane permeability and had been successfully used to label DA and Fe3+ in Hela cells, which presented a potential biological application value as a fluorescent probe for detecting DA and Fe3+.

The synthesis of fluorescent carbon quantum dots for tartrazine detection in food: a novel one-step microwave heating approach

Nowadays, carbon quantum dots (CDs) as semiconductor synthesized nanoparticles have become an attractive subject for lots of applications due to their remarkable features. In the current study, the highly fluorescent (FL) CDs with great characteristics were synthesized through a novel one-step microwave irradiation by citric acid monohydrate and urea as carbon precursors. The as-prepared CDs were quasi-spherical shape with an average diameter of 4.5 nm and emitted bright blue FL under ultraviolet light irradiation (UV). Furthermore, the synthesized CDs possessed different properties such as diverse functional groups, good sensitivity and selectivity, high water-solubility, low toxicity, and significant stability in various environmental conditions. The results indicated that the as-prepared CDs can be applied as a fluorescent probe for detection of different concentrations of tartrazine from 5 to 100 µM in food samples. In addition, the findings revealed that the good linear relationship was obtained between the FL intensity of CDs and different concentrations of tartrazine over the range of 5 to 100 µM with the detection limit of 2.58 µM.

New fluorescent probes based on gallium(III) corrole complexes for the recognition of hydrogen sulfide: A journey from solution to intracellular site

In this work, three fluorescent probes for detection of hydrogen sulfide (H2S) where prepared based on gallium(III) corrole complexes bearing nitro groups at β-pyrrolic positions. Two of the compounds selected, the 3-nitro-5,10,15- tris(pentafluorophenyl)corrolatogallium(III)(pyridine) (CGa-NO2) and the 3,17-dinitro-5,10,15-tris(pentafluorophenyl)corrolatogallium(III)(pyridine) (CGa-2NO2) present one and two nitro groups directly linked to the β-pyrrolic position. The third compound, the (E)-3-(2-nitroprop-1-en-1-yl)-5,10,15-tris(pentafluorophenyl)corrolatogallium(III)(pyridine) (CGa-EtNO2), has a carbon-carbon double bond spacer between the corrole unit and the nitro group. All these derivatives were obtained from 5,10,15-tris(pentafluorophenyl)corrolatogallium(III)(pyridine) (CGa). The precursor CGa and the derivative CGa-EtNO2 behaved as turn-OFF probes, while compound CGa-NO2 responded as a turn-ON probe in the presence of H2S in the pH range of 5–9. Mechanistic studies show that the interaction of H2S with the probes involves its coordination with gallium(III) and in some cases the reduction of the nitro group to a new aminated corrole. While the formation of the coordination complex with H2S is almost immediate, the kinetics of the reduction is slow. Interestingly, for CGa-NO2 the two processes can be explored in a ratiometric sensing of H2S in a non-aqueous solution showing a good linearity over an extended concentration range (5–200 μM). The response of the corroles to H2S in intracellular medium was studied in 2D cultured cells (HeLa).

Sensing of organophosphorus pesticides by fluorescent complexes based on purine-hydrazone receptor and copper (II) and its application in living-cells imaging

In this study, we used purine hydrazone derivatives and coumarin aldehyde to synthesize a novel fluorescent sensor (EDTP) by Schiff base reaction, which exhibited significant selective fluorescence quenching of Cu2+, and a distinct change from brilliant yellow to red is present along with the solution color. The detection limit of EDTP for Cu2+ was 109.52 nM. Job's plot experiment, density flooding theory (DFT) and 1H NMR titration experiments revealed the possible binding mechanism of EDTP to Cu2+, the probe EDTP could achieve highly detection of Cu2+ through forming a 1:1 complex. Additionally, this new fluorescent sensor EDTP-Cu2+ can be further applied in the rapid and selective detection of pesticide residues in solutions. When the EDTP-Cu2+ system was subsequently exposed to organophosphorus pesticides (glyphosate and glufosinate-ammonium), it was observed that the fluorescence was recovered and accompanied by a red to yellow color change. This may be attributed to the strong chelation of glyphosate and glufosinate-ammonium with Cu2+, leading to the dissociation of the EDTP-Cu2+ system and thus triggering the fluorescence recovery effect. The detection limits of the EDTP-Cu2+ system is 2.48 nM for glyphosate and 17.23 nM for glufosinate-ammonium, respectively. Finally, the developed sensor system has been successfully utilized image glyphosate and glufosinate-ammonium fluorescence in living cells. Purine fluorescence probes are a potential fluorescent probe for the detection of metal ions and pesticides due to their good characteristics. This study opens up a new way for the detection of fluorescent probes in pesticides.

Carbon dots-based modularization fluorescent probe for simultaneous detection of Hg2+ and Cu2+ in water, cells and zebrafish

Modular assembly of carbon dots with organic luminescent small molecules can be devoted to picking up a predetermined fluorescent probe detection system for specific targets. In this work, the blue fluorescent carbon dots B-CDs were prepared by using sodium citrate and nitrogen-rich branched polyethyleneimine as precursors through a functional preservation strategy. A modularized, difunctional and ratiometric fluorescent probe B-CDs@RBH with dual-emission was dexterously prepared by simply blending B-CDs and rhodamine b-hydrazide for the detection of Hg2+ and Cu2+. B-CDs can be quenched by Hg2+ through static quenching, while Cu2+ can specifically open the lactam of rhodamine b-hydrazide to form rhodamine B through hydrolysis accompanied by a turn-on orange fluorescence. More interestingly, rhodamine B can absorb the fluorescence of B-CDs through fluorescence resonance energy transfer, resulting in a blue to orange fluorescence color change in the presence of Cu2+. B-CDs@RBH has a low detection limit of 17.79 nM and 4.19 nM for Hg2+ and Cu2+ respectively with a detection range of 0.1–5 μM, which was applied for the ratiometric fluorescence detection of Hg2+ and Cu2+ in cells and zebrafish, and achieved smartphone-assisted on-site water samples detection. The facile modular design of B-CDs@RBH fluorescent probe and convenient on-site detection application are of great benefit in further ascertaining the migration and transformation of heavy metals in biological and environmental samples.

A dual-responsive fluorescent probe for detection of H2O2 and HClO in living cells and Caenorhabditis elegans

A dual-responsive fluorescent probe FDOCl-N-Na was designed and synthesized for the detection of two reactive oxygen species (ROSs) H2O2 and HClO. FDOCl-N-Na displayed individual response toward H2O2 and HClO presenting green and red fluorescence, respectively. FDOCl-N-Na was able to simultaneously monitor the cellular variations of H2O2 and HClO with high selectivity, and high sensitivity under a wide application range of pH. The cell imaging experiments demonstrated that FDOCl-N-Na could successfully distinguish cancer cells from normal cells base on abnormal expression of H2O2 and HClO. Moreover, FDOCl-N-Na also could be applied to tracing the fluctuation of H2O2 and HClO in Caenorhabditis elegans.

Synthesis of benzylidene-indandione derivatives as quantification of amyloid fibrils

The formation of amyloid fibrils due to its association with fatal diseases, including Alzheimer's, has been investigated by many researchers. These common diseases, mostly become verified when it is too late to be treated. Currently, no cure is available for neurodegenerative diseases, and the process of diagnosing amyloid fibrils in the early stages, while there are fewer amyloid fibrils, has become an issue of interest. To do so, determining new probes with the highest binding affinity to the lowest number of amyloid fibrils is necessary. In this study, we proposed to employ new synthesized benzylidene-indandione derivatives as amyloid fibrils fluorescent detection probes. Native soluble proteins of insulin, bovine serum albumin (BSA), BSA amorphous aggregation, and insulin amyloid fibrils were used to evaluate our compounds' specificity to the amyloid structure. While ten synthesized compounds were examined individually, four of them including 3d, 3g, 3i, and 3j showed a high binding affinity with selectivity and specificity to amyloid fibrils, and their binding properties were also confirmed with in silico analysis. The drug-likeness prediction results for selected compounds by Swiss ADME server shows a satisfactory percentage of blood-brain barrier (BBB) permeability and gastrointestinal (GI) absorption for the compounds 3g, 3i, and 3j. More evaluation is needed to determine all properties of compounds in vitro and in vivo.

Protein Determination by Distance and Color Changing &lt;i&gt;via&lt;/i&gt; PEG-Based Hydrogels

Equipment-free detection devices are attractive for point-of-care analysis, especially in resource-limited regions. Distancebased detection is the measurement of color change along the detection path related to the concentration of analytes. Hydrogels are three-dimensional crosslinked polymer networks with tunable properties and may be suitable for distance-based sensors. However, only small ions have been used as the targets in the previous studies. In this work, we demonstrated the possibility of using hydrogel as the distance-based measurement of large biomolecules such as proteins. The hydrogel was prepared with poly(ethylene glycol) diacrylate and a fluorescein derivative as the fluorescent detection probe. The fluorescent alteration in the presence of a target protein, trypsin, can be observed in both intensity-based and distance-based detection. It was found that the effect of the concentration of a fluorescent reagent was not significantly impacted in distance-based detection, while it is essential in intensity-based detection. The relationship between the distance change and the trypsin concentration in the range of 0.5 – 5 mM can be observed. This result showed the possibility of using hydrogel for distance-based detection of large biomolecules.

Dual-State Fluorescent Probe for Ultrafast and Sensitive Detection of Nerve Agent Simulants in Solution and Vapor.

The development of fluorescent probes for detecting nerve agents has been the main concern focus of research because of their lethal toxicity for humans. Herein, a probe (PQSP) based on the quinoxalinone unit and the styrene pyridine group was synthesized and could visually detect a sarin simulant diethyl chlorophosphate (DCP) with excellent sensing properties in solution and solid states. Interestingly, PQSP showed an apparent intramolecular charge-transfer process by catalytic protonation after reacting with DCP in methanol, accompanied with the aggregation recombination effect. The sensing process was also verified by nuclear magnetic resonance spectra, scanning electron microscopy, and theoretical calculations. In addition, the papered test strips of loading probe PQSP exhibited an ultrafast response time within 3 s and high sensitivity with a limit of detection of 3 ppb for the detection of DCP vapor. Therefore, this research provides a designed strategy for developing the probes with dual-state emission fluorescence in solution and solid states for detecting DCP sensitively and rapidly, which can be fabricated as chemosensors to visually detect nerve agents in practice.

A Poly(carbazole-alt-triazole) with Thiabendazole Side Groups as an "On-Off-On" Fluorescent Probe for Detection of Cu(II) Ion and Cysteine.

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.

A highly selective and easily acquisitive near-infrared fluorescent probe for detection and imaging of hydrogen sulfide in cells

Hydrogen sulfide (H2S) plays a substantial role as a messenger in the physiological and pathological processes of many diseases. Recently, the fluorescence probe of H2S based on organic dye has attracted great attention. However, the emission of many probes is in the UV–vis region (400–600 nm), so it has the disadvantages of shallow tissue penetration and more vulnerable to spontaneous fluorescence interference. Although several H2S probes have been developed that emit more than 650 nm, there is a complex structure difficult to synthesize or unstable in storage. Aimed at simply structural and easily synthesized H2S fluorescent probes with emission wavelength more than 650 nm, a novel near-infrared (NIR) probe (NIR-H2S) here was rationally designed with 4-(2-carboxyphenyl)-7-(diethylamino)-2-(4-hydroxystyryl)chromenylium (NIR-OH) as a fluorescent dye and 2,4-dinitrophenyl moiety as a recognition group. Addition of H2S, the “turn-on” NIR fluorescence response at 736 nm of NIR-H2S was displayed, accompanied by a visual colour change from purple to green when excited at 686 nm. As an easily acquisitive H2S probe, NIR-H2S has been successfully applied to cell imaging for H2S detection with the advantages such as long fluorescence emission, low toxicity, high sensitivity and strong selectivity.

Polyethylenimine-functionalized nitrogen and sulfur co-doped carbon dots as effective fluorescent probes for detection of Hg2+ ions

Surface modification of nitrogen and sulfur co-doped carbon quantum dots (N, S-CDs) were performed using cysteine and polyethylenimine as raw materials. The prepared N, S-CDs exhibited excitation-independent in the range of 300–380 nm. Furthermore, mercury(II) ions (Hg2+) can effectively quench the fluorescence intensity of the N, S-CDs. Based on this, we developed a fluorescence sensor with high sensitivity and selectivity to detect Hg2+. Under optimized conditions, the sensor showed good linearity in the range of 0–500 nM, and the limit of detection is 9.2 nM. Further, the sensor showed high sensitivity to Hg2+ in lake water and rice samples. The recovery of the Hg2+ in lake water and rice samples ranged between 98.2 % and 109.5 % with a relative standard deviation below 5.8 %. With outstanding sensitivity and selectivity, the fluorescence sensor provides a promising platform for monitoring Hg2+ in real samples.

Fluorescent Probe Combined with Photoelectric Analysis Technology for Detection of Escherichia coli.

Food safety is facing great challenges in preventing foodborne diseases caused by pathogenic pollution, especially in resource-limited areas. The rapid detection technique of microorganisms, such as immunological methods and molecular biological methods, plays a crucial key in timely bioanalysis and disease treatment strategies. However, it is difficult for these methods to simultaneously meet the criteria of simple operation, high specificity, and sensitivity, as well as low cost. Coconut water is known as the "water of life" in Hainan. It is a refreshing and nutritious beverage which is widely consumed due to its beneficial properties to health. Coconut water processing is an important pillar industry in Hainan. The detection of pathogenic microorganisms, such as Escherichia coli, in coconut water has become an important factor which has restricted the upgrading and development of this industry. Based on the needs of industrial development, we developed a microbial photoelectric detection system which was composed of a fluorescent probe detection reagent and a photoelectric sensor detection device. This system combined microbial enzyme targets, selective fluorescent substrate metabolism characteristics, and a photoelectric sensor signal transduction mechanism, which produce a strong signal with a high signal-to-noise ratio. The microbial detection system developed here has a simple structure, simple and convenient operation, short detecting time (≥2 h), and high sensitivity (1 CFU/mL). This system may also enable early warning and monitoring programs for other pathogenic microorganisms in order to promote the overall competitiveness of the Hainan coconut water industry.

A novel colorimetric and ratiometric fluorescent probe for detection of Cu2+ with large stokes shift in complete aqueous solution

A novel colorimetric and ratiometric fluorescent probe 1 for Cu2+ was designed and synthesized. 1 exhibited maximum absorption and fluorescence emission peaks at 385 nm and 495 nm respectively, with large Stokes shift of 110 nm. In sensing of Cu2+, the maximum absorption and fluorescence emission peaks generated bathochromic shift to 415 nm and 560 nm respectively, due to the Cu2+-induced hydrolysis reaction of the picolinate moiety in 1. Meanwhile, the solution of 1 turned from pale yellow to yellow in visible light and from pale green to orange under a 365 nm UV lamp. 1 displayed remarkable change in the ratio (F560 nm/F495 nm) of the fluorescence intensity (R/R0 up to 23-fold), high sensitivity (detection limit of 0.62 μM), fast response time (within 2 min), and excellent selectivity for Cu2+ over other metal ions in complete aqueous solution.