Fluorescent Sensor For Cu2 Research Articles

A Novel Rhodamine B Derivative as a "Turn-on" Fluorescent Sensor for Cu2+ with High Selectivity and Sensitivity.

The number of "turn-on" fluorescent probes for Cu2+ is relatively limited, and interference from other metal cations presents a significant challenge for these sensors. In this study, we synthesized and characterized a rhodamine B-based sensor, designated as RBHP, using 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (PMBP) and rhodamine B hydrazide. Selectivity, sensitivity, solvent effects, water content, and pH of RBHP in relation to Cu²⁺ were conducted. RBHP exhibited an exceptionally low fluorescence background signal in acetonitrile and demonstrated a "turn-on" fluorescent response to Cu²⁺. The PMBP-based acylhydrazone moiety and acetonitrile as the detection solvent are crucial for the selective detection. RBHP shows potential as a highly selective and sensitive fluorescent sensor for Cu2+.

Novel highly selective quinoline-based fluorescent chemosensors for quantitative analysis of Cu(II) ion in water and food

While copper (Cu2+) is a vital cofactor in numerous enzymatic processes, its homeostasis is critical. Selective sensors for Cu2+ in food matrices are paramount for ensuring adherence to safety regulations and dietary interaction studies. In this work, novel derivatives of 8-aminoquinoline (L1-L4) with extended π-conjugation and various N-substituents were synthesized and evaluated as fluorescent sensors for Cu2+. The 2-pyridinecarbonyl-substituted derivative L3 exhibited sharp fluorescence quenching selectively in the presence of Cu2+. This compound presents high selectivity for Cu2+ even in the presence of other metal ions. The L3-based fluorescent sensor provides a Cu2+ detection limit of 77 nM, surpassing many existing sensors. The quantifications of Cu2+ in water, food supplements, and wines using this sensor have demonstrated good agreement with those obtained using the standard ICP technique. Notably, L3 also facilitates Cu2+ detection in microliter sample volumes at subnanomole levels using paper-based sensors, opening doors for portable and cost-effective on-site testing.

Development of sensitive biomass xylan-based carbon dots fluorescence sensor for quantification detection Cu2+ in real water and soil

Copper ions (Cu2+) pose significant risks to both human health and the environment as they tend to accumulate in soil and water. To address this issue, an innovative method using biomass-derived fluorescent carbon dots (D-CDs) synthesized via a hydrothermal process, with xylan serving as the carbon source was developed. D-CDs solution exhibited remarkable sensitivity and selectivity as a fluorescence sensor for Cu2+, boasting a low detection threshold of 0.64 μM. In order to facilitate real-time monitoring of Cu2+, solid-state fluorescent nanofiber membrane (NFD-CDs) through electrospinning was engineered. Additionally, D-CDs demonstrated successful Cu2+ detection in various real water samples, including those sourced from Xuanwu Lake, the Yangtze River, tap water, and bottled water, with accurate recovery rates observed. As a result, this research introduces a dual-mode analytical system for onsite detection of Cu2+ in real scenarios. By harnessing biomass-derived fluorescent CDs materials and solid-state fluorescence sensors, this approach offers a promising solution for addressing the challenges associated with Cu2+ contamination.

Synthesis and characterization of a rhodamine derivative as a selective switch-on fluorescent sensor for Cu2+ ions in aqueous PBS buffer and living cells

A novel rhodamine-based receptor molecule (L1) was synthesized via the reaction between rhodamine hydrazide and acetylacetone.

Facile synthesis of NS-doped carbon dots as sensitive “ON-OFF-ON” fluorescent sensor for Cu2+ and GSH detection

In this paper, a novel nitrogen and sulfur co-doped carbon quantum dots (NS-CQDs) were successfully prepared by a dehydration exothermic carbonization method. The NS-CQDs exhibited uniform size distribution, splendid photostability, and bright fluorescence emission with a fluorescence quantum yield of 24.1 %. It was found that Cu2+ could quench the fluorescence at 467 nm based on the static quenching effect when Cu2+ was added to the NS-CQDs. At this time, the fluorescence sensor changed from the “ON” state to the “OFF” state. When glutathione (GSH) was further introduced into the NS-CQDs/Cu2+ system, the fluorescence intensity of NS-CQDs was amazingly restored through the coordination reaction between GSH and Cu2+. The fluorescence sensor changed from the “OFF” state to the “ON” state. Therefore, NS-CQDs as an “ON-OFF-ON” fluorescence sensor was designed for sequential detection of Cu2+ and GSH. Furthermore, this study successfully demonstrated the sensor’s ability to selectively detect Cu2+ and GSH within a wide concentration range. Specifically, the detection range for Cu2+ was 0.1 μM−200.0 μM with a detection limit of 0.07 μM, while the range for GSH was 0.6 μM−180.0 μM with a detection limit of 0.1 μM. Most importantly, the NS-CQDs nanosensor could reliably monitor Cu2+ and GSH levels in human serum samples, with significant potential for practical applications.

Dual-function sensor based on NH2-MIL-101(Fe)@Cu/CeO2 nanozyme for colorimetric and fluorescence detection of heavy metals

Heavy metal ions exhibit significant toxicity and pose threats to ecosystems and human health. Therefore, the development of sensitive detection methods is crucial. Nanozyme-based heavy metal sensors have garnered attention, yet existing nanozymes often suffer from low catalytic activity, limited functionality, and unclear mechanisms. To address these issues, this study successfully synthesized an organic-inorganic hybrid nanozyme (NH2-MIL-101(Fe)@Cu/CeO2) using doping and composite techniques, creating a dual-functional sensor. It's worth noting that in NH2-MIL-101(Fe)@Cu/CeO2, copper doping and heterojunction formation may increase oxygen vacancy concentration, promoting electron transfer. Compared to individual components like amino-terephthalic acid iron (III) metal-organic framework (NH2-MIL-101(Fe)) and copper-doped cerium dioxide (Cu/CeO2), this composite material exhibited enhanced peroxidase-like activity (oxidase-like, peroxidase-mimic, catalase-mimic, and superoxide dismutase-mimic). Particularly, NH2-MIL-101(Fe)@Cu/CeO2 displayed outstanding peroxidase-like activity, with Km values of 0.02 mM for TMB and 0.49 mM for H2O2, surpassing most nanozymes, along with high reaction rate (Vmax = 3.82 × 10−5 mM/s). Leveraging NH2-MIL-101(Fe)@Cu/CeO2's peroxidase-like behavior, TMB oxidation turned blue, inhibited by glutathione causing fading. Importantly, Hg2+ complexed with glutathione's thiol group forming GSH-Hg2+, restoring the blue color. Utilizing these properties, a colorimetric sensor for Hg2+ detection was developed. Furthermore, NH2-MIL-101(Fe)@Cu/CeO2 also exhibited remarkable fluorescence performance; Cu2+ binding with amino groups quenched fluorescence. Exploiting this phenomenon, a fluorescent sensor for Cu2+ detection was devised. Results demonstrated this dual-functional sensor's advantages: high sensitivity (LODHg2+ = 0.7 nM, LODCu2+ = 0.1 µM), strong selectivity, wide linear range (0.01 ∼ 4 µM and 8 ∼ 600 µM), and robust stability (90 % activity retained after three cycles).

Non-aromatic single amino acid, lysine: A simple fluorescence sensor for selective detection of Cu2+ and Co2+ with colorimetric distinction by the virtue of its self-aggregation behaviour

Non-aromatic amino acids are mostly considered as non-emissive due to their lack of conventional fluorophores. However, at high concentrations, they can undergo conformational rigidification via self-aggregation and emit in the visible range. Herein, we have exploited that very property of non-aromatic amino acids as a fluorescence sensor. To the best of our knowledge, this is the first report demonstrating a single unmodified non-aromatic amino acid, Lysine (Lys) as a selective and sensitive fluorescence sensor for the detection of Cu2+ and Co2+ along with colorimetric distinction. An as-prepared aqueous solution of Lys (6.8 mM) served as a fluorescence sensor for Cu2+ and Co2+ with a detection limit of 420 nM and 460 nM, respectively in water. The instantaneous appearance of blue and pink color upon adding Cu2+ and Co2+, respectively to the Lys solution makes the system useful for their real-time analysis. The sensing of Cu2+ and Co2+ are also demonstrated through the fabrication of paper strips. Moreover, the sensor could detect Cu2+ and Co2+ in real water samples (lake water and tap water). The exceptionally low cost (<1 U.S. cent/10 mg Lys), reversibility of the sensor, and its ease of use uniquely qualify Lys as a remarkably simple fluorescent sensor.

3-Pyridylazoindole derivatives as photoswitches: Synthesis, photoswitching behavior research, and applied to “on–off” fluorescence sensor for Cu2+ combined with theoretical calculations

In order to exploit the compounds with excellent photoswitching properties, a series of 3-pyridylazoindole derivatives were designed and synthesized. The molecular structures were characterized via1H and 13C NMR, the structure of typical compound A6 was also confirmed via single crystal X-ray diffraction. This series of 3-pyridylazoindole derivatives had outstanding characteristics compared with traditional azo photoswitches, such as the red-shifted of maximum absorption wavelength, UV/vis light isomerization in both directions (PSScis: 45–78%; PSStrans: 47–98%) can be achieved easily and broad range of trans-isomer thermal half-lives from minutes to days (0.44–38.4 h). The relationship between structure and properties verified that the photoswiching behavior of azo photoswitches was closely related to the conjugation groups and electronic effects modifying groups. Besides, the frontier molecular orbital and differences of spatial structure calculated by density functional theory (DFT) further explained the performance characteristics of photoswitches. What more, the compound A7 exhibited excellent aggregation-induced emission (AIE) property and could also be used as selective “on–off” fluorescence sensor for Cu2+, which expanded the photochemical properties of 3-pyridylazoindole derivatives.

Fabrication of surface ion imprinting rice husk-based polymer for selective detection and efficient adsorption of Cu2+ in lake water

With the deepening of the concept of recycling economy and green chemistry, selective detection and capture of Cu2+ from lake water by biosorbent are of great significance. Herein, the Cu2+ ion-imprinted polymers (RH-CIIP) with organosilane containing hydroxyl and Schiff base groups (OHSBG) as ion-receptor, fluorescent chromophores and cross-linking agent, and Cu2+ as template ion, were fabricated via surface ion imprinting technology by employing mesoporous silica MCM-41 (RH@MCM-41) as supporter. The RH-CIIP could be exploited as a fluorescent sensor for Cu2+ with high selective compared with Cu2+ non-imprinted polymers (RH-CNIP). Additionally, the LOD was calculated to be 5.62 μg/L, which is far below WHO standard for Cu2+ in drinking water of 2 mg/L, and more lower than the reported methods. Moreover, the RH-CIIP can also be utilized as an adsorbent for the effective elimination of Cu2+ from lake water with the adsorption capacity of 87.8 mg/g. Besides, the kinetic features of adsorption were well defined by the pseudo-second-order model and the sorption isotherm was in agreement with the Langmuir model. Meanwhile, the interaction of RH-CIIP and Cu2+ was investigated using theoretical calculations and XPS. Finally, RH-CIIP was able to remove almost 99 % Cu2+ in lake water samples that satisfied the drink water standard.

Stable chitosan fluorescent nanofiber sensor containing Eu3+ complexes for detection of copper ion

In this work, a luminescent lanthanide complex, namely, Eu(tta)3phen (Eu = europium, tta = 2-thenoyltrifluoroacetone, phen = 1, 10-phenanthroline) is used as a luminescent dopant to prepare fluorescent nanofiber films. The resulting nanofibers (CS/PEO-SiO2@Eu(tta)3phen) are composed of chitosan and polyethylene oxide containing silica nanoparticles, encapsulating the Eu(tta)3phen. The nanofibers are stabilized by treatment with sodium bicarbonate (NaHCO3) aqueous solution as neutralizer and then repeatedly washed with deionized water. A more stable Na-CS/PEO-SiO2@Eu(tta)3phen fiber film is obtained as a fluorescence sensor for Cu2+ ions. The Na-CS/PEO-SiO2@Eu(tta)3phen has high sensitivity, and a wide detection range. The response is linear in the concentration range from 10 to 90 μmol/L, and the detection limit is 0.826 μmol/L. In addition, Na-CS/PEO-SiO2@Eu(tta)3phen nanofiber film can be used as a recyclable sensor for the detection of Cu2+ ions in aqueous solution due to its good recyclability, selectivity and rapid optical response.

Fluorescence quenching mechanism of P-doped carbon quantum dots as fluorescent sensor for Cu2+ ions

Carbon quantum dots (CQDs), were gaining traction as promising optical detection materials due to its unique properties.In this research, rice stock is utilized as source of carbon and phosphorus is utilized as source of phosphorus to render phosphorus-doped carbon quantum dots.The P-CQDs may be generated in an economical and environmentally responsible manner using this technique.Under optimal conditions of temperature and pH, the synthesized green fluorescent P-CQDs were monodispersed and spherical in shape having an average size of 5.4 nm and a high quantum yield of 32.61%. Because of the interaction of P-CQDs and Cu2+ ions, the fluorescence properties of P-CQDs are quenched when they are in the presence of Cu2+ ions.With the incorporation of Cu2+ ions into P-CQDs, electron transport was enhanced, which may lead to fluorescence quenching, under optimal circumstances.According to the results of a spectroscopic analysis, Cu2+ ions can be detected at concentrations ranging from 0 to 260 μM, with a lower limit of detection of 0.032 μM.A real implementation of detecting Cu2+ in tap water was also carried out, and the results showed a satisfactory recovery rate. In a direct result of these, the implementation of a Cu2+ sensor may also be considered a real scenario.

Click Chemistry ‐ Inspired Synthesis of Porphyrin Hybrid Glycodendrimers as Fluorescent Sensor for Cu(II) Ions

AbstractAn expeditious and modular CuAAC ‘click’ protocol has been exploited for the construction of porphyrin cored hybrid glycodendrimers of G1 and G2 generation. The developed porphyrin hybrid glycodendrimers were characterized using extensive spectral analysis including NMR (1H, 13C, and 19F), MS, MALDI‐TOF, IR, and SEC datas and evaluated for their sensing ability for a range of metal ions, where they displayed notable sensing for Cu(II) ion with solvatochromism properties.

Down shifting luminescent Eu3+ doped Ba6Gd2W3O18 perovskite Nanosensor for Cu2+ ions in drinking water and food samples

Down shifting red luminescent Eu3+ doped Ba6Gd2W3O18 (BGWO: y mol Eu3+; y = 0.00, 0.03, 0.07, 0.10, 0.15) is synthesized for the first time by citrate sol–gel method as a novel fluorescent sensor for Cu2+ in drinking water and food samples. BGWO: y mol Eu3+ is characterized with nano-domain crystalline cubic perovskite structure. PL emission, lifetime measurements and CIE chromaticity coordinates diagram confirmed that BGWO: 0.10 mol Eu3+ has a strong pure red emission color with long lifetime. BGWO: 0.10 mol Eu3+ Nanosensor shows a quite selectivity and sensitivity towards copper ion in comparison to other studied metal ions. Copper sensitivity is studied by BGWO: 0.10 mol Eu3+ Photoluminescence (PL) quenching method. Stern-Volmer plot was achieved over the concentration 0.01 to 100 μM with correlation coefficient (R2) of 0.9894 and a detection limit of 0.138 μM. The sensing mechanism is discussed in detail. Optimized BGWO: 0.10 mol Eu3+ Nanosensor was applied for copper detection in drink water and food sample with high recovery value.

Aggregation-induced emission-active fluorescent polymer sensors for the detection of water in organic solvents, Cu2+ and hemolysis

The hydrophobic polymer HDDA-EDT-SADA with aggregation-induced emission (AIE) property was synthesized via the thiol-ene click copolymerization of salicylaldehyde azine (SA) derivative diacrylate monomer SADA and commercially available 1,2-ethanedithiol (EDT) and 1,6-hexanediol diacrylate (HDDA). HDDA-EDT-SADA was found to display unexpected intense fluorescence in acetone and DMSO compared to that in other good solvents, which dramatically decreased by adding small amount of water. We demonstrate that HDDA-EDT-SADA can be used as a fluorescent sensor for water detection in acetone and DMSO. To improve the water solubility of the AIE-active polymer, SADA was copolymerized with dithiothreitol (DTT) and poly(ethylene glycol) diacrylate (PEGDA) to give an amphiphilic AIE polymer PEGDA-DTT-SADA. Similar fluorescence phenomenon was also found in DMF, suggesting that PEGDA-DTT-SADA could serve as an indicator for water detection in DMF. Thanks to the PEG segments and DTT units, the PEGDA-DTT-SADA was able to well-disperse in water via the formation of stable micelles. The PEGDA-DTT-SADA selectively complexed with Cu2+ and thus could be used as a fluorescent sensor for Cu2+ detection in aqueous media. Moreover, the PEGDA-DTT-SADA could be utilized as a fluorescent sensor for hemolysis ratio detection of red blood cells (RBCs) due to the inner filter effect.

Hydrazone-based Schiff base dual chemosensor for recognition of Cu2+ and F− by 1:2 demultiplexer, half adder, half subtractor, molecular keypad lock and logically reversible transfer gate logic circuits and its application as test kit

A new hydrazone-based chemosensor R was synthesized as a highly colorimetric and fluorescent sensor for Cu2+ and F− ions in DMSO. The chemosensor R characterized by UV–Vis absorption and fluorescence spectroscopic studies. The binding behavior of the chemosensor R toward Cu2+ and F− ions was investigated by UV–Vis absorption, 1HNMR and fluorescence spectroscopic studies. By adding Cu2+ ion to the chemosensor R, a mental-to-ligand charge-transfer transition (MLCT) was exhibited at 410 nm and the decrease of fluorescence at 532 nm was observed with concomitant appearance of a new peak at 570 nm. A new absorption peak at 513 nm and enhancement of the emission band at 532 nm were observed in the presence of F− ions. The –NH unit in hydrazone- based chemoreceptor is the proper H-bond donor which can act as a selective sensor for F− ions. The detection limits of the compound R (obtained by the 3σ method) for Cu2+ and F− ions are 3.51 × 10−6 and 3.26 × 10−6 mol L−1, respectively. According to the observed changes in the absorbance and emission intensity a specific wavelength as a result of two inputs (Cu2+ and F−), it can be concluded that the chemosensor R mimics the function of XOR, INH, IMP and AND logic gates and half adder, half subtractor, 1:2 demultiplexer, complementary IMP/INH logic, molecular keypad lock and logically reversible transfer gate logic circuits with a single molecule. The test kits can be utilized for detecting fluoride anion with different concentration in aqueous media by naked-eyes, without any optical instrument in undeveloped regions.

A highly selective fluorescent sensor for Cu2+ based on naphthalimide containing aza‐crown ether

AbstractThe development of a fluorogenic chemosensors with high sensitivity for copper ion (Cu2+) has been receiving great attention in recent years because of their potential application in clinical biochemistry and the environment studies. In the present study, we designed and synthesized a fluorescent probe, Np‐azaCE, with 1,8‐naphthalimides as a core structure and 1,4‐diaza‐9‐crown‐3‐ether as a copper ion tweeze, which showed selective and sensitive fluorometric change upon addition of a copper ion. The Np‐azaCE chemosensor was highly selective for Cu2+ over the other metal ions with fluorescent quenching. Finally, the Cu2+ detection limit and job's plot of Np‐azaCE were calculated using UV–visible spectrophotometer and fluorescence spectrophotometer.

Carbazole‐based dual‐functional chemosensor: Colorimetric sensor for Co2+ and fluorescent sensor for Cu2+ and its application

AbstractA new carbazole derivative CNS was prepared by the condensation of 2‐hydrazine benzothiazole with 3‐aldehyde‐6‐naphthalene‐N‐butyl carbazole, which could highly selectively discriminate Co2+ and Cu2+ in different solvent systems. CNS could enable the recognition of Co2+ by the “naked eye,” with the color changing from colorless to pale yellow in DMSO/H2O (v/v = 1:1). The addition of Cu2+ made the fluorescence emission intensity increase nearly 10 times, which was accompanied by a weak blue shift of the emission peak in CH3CN. Under the illumination of 365 nm ultraviolet lamp, the color of the CNS solution changed from light blue to dark blue after Cu2+ was added. The binding process could be reasonably speculated by spectrometric titrations, 1H NMR, mass spectrometry (MS) analysis, and density functional theory (DFT) calculation. The results of fluorescence electron microscopy showed that CNS could be used as a fluorescent sensor to detect Cu2+ in Hela cells. In addition, CNS was successfully used for the detection of Cu2+ in actual water samples.

Preparation, luminescence and photofunctional performances of a hybrid layered gadolinium-europium hydroxide

The design and fabrication of rare earth ions incorporated into the inorganic/organic hybrid materials have attracted growing attention for seeking improved optical properties and photofunctional performances. In this paper, a novel hybrid composite based on the layered rare earth hydroxides was successfully prepared by the ion-exchange and intercalation chemical process. The rare earth elements in the composite contain gadolinium (Gd) and europium (Eu) and the molar ratio of Gd to Eu is kept constant at 1.9 : 0.1. Organic sodium dodecyl sulfonate and dye coumarin-3-carboxyllc acid are simultaneously incorporated into the layered rare earth hydroxides as supporting agent and light-harvesting antenna, respectively. The resulting hybrid layered rare earth hydroxides exhibit the enlarged interlayer distance with about 2.60 nm, and the chemical composition was confirmed through X-ray diffraction, carbon, hydrogen and nitrogen (CHN) elemental analysis, infrared spectroscopy, and thermogravimetric analysis. The layered solid compound shows the characteristic red emission corresponding to the 5D0→7F2 transition of Eu3+ ion, and the luminescence intensity of the optimized compound is greatly enhanced as compared to its corresponding nitrate and the hybrid composite without the introduction of dye molecule. The hybrid layered rare earth hydroxides can be exfoliated into bright colloidal solution, which show superior recognition capability to Cu2+ ion with the distinct luminescence quenching. The large quenching constant (1.4 × 104 L/mol) and low detection limit (0.35 μmol/L) are achieved for Cu2+ ion, implying a “turn-off” fluorescent sensor for Cu2+ detection. Moreover, a transparent film was prepared based on the colloidal solution and displays the typical red emission in folded shape. The new hybrid compound with enhanced luminescence and excellent photofunctional performances is expected to be applied in the fields of fluorescent sensing and flexible optical devices.

A Rare Natural Benzo[k,l]xanthene as a Turn-Off Fluorescent Sensor for Cu2+ Ion.

Rapid and efficient analyses of copper ions are crucial to providing key information for Cu2+ in living cells because of their biological importance. In this study, we reported one new turn-off fluorescent sensor for Cu2+ with a benzo[k,l]xanthene core, which served as an efficient cation sensor for copper ion over a wide range of other cations (Na+, K+, Ag+, Hg2+, Cd2+, Co2+, Ni2+, Zn2+, Mg2+, and Fe3+) owing to the catechol group in the aromatic core. The sensor showed selectivity for Cu2+ over other ions; the logKβ for Cu2+ binding to compound 1 had a value of 13.265. In the presence of Cu2+, sensor 1 provided significant fluorescence decrement; Co2+, and Ni2+ caused a fluorescence decrement when employed at a higher concentration than Cu2+, while Na+, K+, Hg2+, Cd2+, Zn2+, and Mg2+ metal ions produced only minor changes in fluorescence intensity. Fluorescence experiments demonstrate that compound 1 may have an application as a fluorescent probe for detecting Cu2+ with a limit of detection of 0.574 µM.

Synthesis of calix[4]arenes bearing thiosemicarbazone moieties with naphthalene groups: Highly selective turn off/on fluorescent sensor for Cu(II) recognition

Calix[4]arenes-based fluorescent chemosensors containing thiosemicarbazone as a binding site and naphthalene as a fluorogenic unit in a 1,3-alternate (L1) and cone (L2) conformation, were synthesized and examined for their binding abilities towards anions and cations using different spectroscopic techniques. Both receptors L1 and L2, exhibited an off/on fluorescence behaviour due to complex formation with Cu(II). They showed selective recognition of Cu(II) in presence of other cations and anions detecting up to 4.25 µg/L for L1 and 1.58 µg/L for L2, both in acetonitrile. The complexation behaviour was studied by 1H NMR and FT-IR spectral analysis, indicating that copper interacts with sulphur and with imine nitrogen of the thiosemicarbazone. No major differences in the selectivity and sensitivity were found between calix[4]arene receptors in 1,3-alternate and cone conformation. The 1H NMR spectra indicates that receptor L2 changed its conformation from cone to pinched cone, stiffening the conformation due to interaction of the thiosemicarbazone moiety with copper.