Detection Of Copper Ions Research Articles

Nitrogen-Doped Carbon Dots Prepared via Microchannel Method for Visual Detection of Copper Ions.

Copper ions (Cu2+) play a crucial role in biological processes; however, excessive intake can result in severe health problems. Current methods for detecting copper ions are both expensive and complex. Therefore, there is a need for efficient and straightforward visual detection methods. In this study, novel nitrogen-doped carbon dots (N-CDs) were synthesized via a microchannel method using diethylenetriamine and citric acid as precursors and were characterized by TEM, XRD, and IR, among others. The N-CDs demonstrated high selectivity and strong fluorescence, showing a linear quenching response to copper ions with a detection limit of 46 nM, whereas other common metal ions, such as Ca2+ and Mg2+, exhibited negligible interference even at higher concentrations. These N-CDs were subsequently applied to test paper, allowing for on-site visual and quantitative detection of copper ions via a colorimetric method. This approach provides a novel solution for the rapid detection of copper ions, with significant potential in environmental monitoring, public health, and industrial applications.

Luminescent Re(I) sensors for copper ion detection in the lifetime based mode

Luminescent Re(I) sensors for copper ion detection in the lifetime based mode

A novel overtone peak self-referencing fluorescent sensor based on a bipyridine-linked covalent organic framework for highly sensitive copper ion detection.

This study reports a novel ratiometric fluorescence sensor based on a tetraphenylethylene-bipyridine covalent organic framework (TPE-Bpy-COF) for the sensitive detection of Cu2+, leveraging the unique coordination properties of the bipyridine moieties. The interaction between Cu2+ and the nitrogen atoms in the bipyridine units induces fluorescence quenching at 500 nm through an efficient host-guest electron transfer mechanism, where excited-state electrons from the COF framework are transferred to the vacant orbitals of Cu2+. Upon excitation at 410 nm, the sensor exhibits a primary emission peak at 500 nm, which is quenched in the presence of Cu2+, while an overtone peak at 820 nm remains stable, serving as an internal reference for ratiometric measurements and significantly enhancing the accuracy and reliability of the sensor. The detection limit for Cu2+ is 0.1 μM, with the dual-emission system and the strong affinity of the bipyridine units for Cu2+, further improving the sensor's sensitivity and selectivity. Additionally, the sensor demonstrated excellent recovery rates in real water samples, confirming its practical applicability in environmental monitoring.

Template-assembly activation of primer exchange reaction for on-site and sensitive detection of copper ions in blood.

The sensitive and accurate detection of copper ions is crucial for public health, medical research, and environmental monitoring. In this study, we developed a sensor based on template-assembly activation of the primer exchange reaction (PER) for the on-site detection of copper ions in blood. Copper ions triggered the assembly of two template fragments into a hairpin structure via a click-chemistry reaction, activating the PER. Polymerase then repeatedly guided the polymerization of multiple primers along the assembled PER template, generating amplified products containing G-triplex sequences. These G-triplex structures specifically enhanced the fluorescence of thioflavin T and exhibited peroxidase-like activity, serving as dual-functional signal reporters for both fluorescence and colorimetric outputs. The sensor effectively amplified a single copper ion signal into multiple G-triplex signals, achieving high sensitivity with detection limits of 68.5nM in fluorescence mode and 70.4nM in colorimetric mode. The system also demonstrated strong selectivity, due to the high specificity of the click-chemistry reaction for copper ions. The dual-mode detection minimized false signals and improved accuracy through cross-verification. Additionally, both fluorescence and colorimetric signals were easily measurable without complex instrumentation, enabling flexible application. The method was successfully applied to blood samples, showcasing its robust performance. This sensor offers a promising alternative for copper ion detection with broad potential applications in public health, medical research, and environmental monitoring.

A dual-emission fluorescence sensor based on TCPP@UiO-66-NH2 for high-sensitivity detection of copper ions

A dual-emission fluorescence sensor based on TCPP@UiO-66-NH₂ for high-sensitivity detection of copper ions

Integrating L-Cys-AuNCs in ZIF-8 with Enhanced Fluorescence and Strengthened Stability for Sensitive Detection of Copper Ions.

Gold nanoclusters (AuNCs) have been widely investigated because of their unique photoluminescence properties. However, the applications of AuNCs are limited by their poor stability and relatively low fluorescence. In the present work, we developed nanocomposites (L-Cys-AuNCs@ZIF-8) with high fluorescence and stability, which were constructed by encapsulating the water-dispersible L-Cys-AuNCs into a ZIF-8 via Zn2+-triggered growth strategy without high temperature and pressure. The maximum emission wavelength of the L-Cys-AuNCs@ZIF-8 composite was at 868 nm, and the fluorescence intensity of L-Cys-AuNCs@ZIF-8 was nearly nine-fold compared with L-Cys-AuNCs without the ZIF-8 package. The mechanism investigation by fluorescence spectroscopy and X-ray photoelectron spectroscopy showed that L-Cys-AuNCs@ZIF-8 impeded ligand rotation, induced energy dissipation, and diminished the self-quenching effect, attributing to the spatial distribution of L-Cys-AuNCs. Based on the high fluorescence efficiency of L-Cys-AuNCs@ZIF-8, a "signal off" detective platform was proposed with copper ions as a model analyte, achieving a sensitive detection limit of Cu2+ at 16.7 nM. The quenching mechanism was confirmed, showing that the structure of the L-Cys-AuNCs@ZIF-8 nanocomposites was collapsed by the addition of Cu2+. Attributing to the strong adsorption ability between copper ions and pyridyl nitrogen, the as-prepared L-Cys-AuNCs@ZIF-8 was shown to accumulate Cu2+, and the Zn2+ in ZIF-8 was replaced by Cu2+.

Functionalized magnetic hydrogen-bonded organic framework for preconcentration and rapid detection of lead and copper ions in water

Functionalized magnetic hydrogen-bonded organic framework for preconcentration and rapid detection of lead and copper ions in water

Curcumin-Derived Turn-Off Fluorescent Probe for Copper (II) Ion Detection and Live Cell Imaging Applications.

A curcumin-derived chemosensor 4,4'-((1E,3Z,5Z,6E)-3,5-bis((2hydroxyphenyl)imino) hepta-1,6-diene-1,7-diyl)bis(2-methoxyphenol) (HIBMP) was developed from curcumin and o-aminophenol using Schiff base condensation method. HIBMP selectively recognizes Cu (II) ion (Cu (II)) relative to other tested metal ions. Selective binding of Cu (II) ion turns off the fluorescent property of HIBMP and shows no interference with other metal ions. Moreover, the favourable binding of Cu (II) with HIBMP was noticed by a good linearity between the fluorescence intensity and concentration of Cu (II) with a range of 0-15.6 × 10-7 M, and the limit of detection was determined to be as low as 30.1 nM. Furthermore a 1:1 stoichiometry was identified from the results of Job's plot and HR-MS. Density functional theory (DFT) calculation results expressed that the intramolecular charge transfer (ICT) during chelation is responsible for quenching of fluorescence. Besides, the fluorescence life time measurement and ethylenediaminetetraacetic acid (EDTA) titration method revealed the stability and reversibility of the sensor. Practical use of the sensor was achieved through the quantitative analysis of spiked Cu (II) ion in real water samples with good recoveries, and biological experiments exposed that the sensor was less toxic and could be applied in fluorescence imaging of Cu (II) in living cells.

A graphene quantum dots based dual-modal fluorometric and visualized detection of copper ions

In this study, we present a dual-modal fluorometric and visualized detection method for Cu2+ ion, leveraging the synergistic properties of graphene quantum dots (GQDs) and Cu2+ ion catalyzed Fenton-like reaction. The Fenton-like reaction of Cu2+ ions and ascorbate generates highly reactive hydroxyl radical (·OH), which effectively disrupt the structure of GQDs, leading to fluorescence quenching. Under optimized conditions, the fluorescence quenching degree exhibited a linear correlation with Cu2+ concentration within the range of 40 to 2000 nM, enabling the detection of Cu2+ ions as low as 40 nM. Furthermore, we demonstrated the feasibility of semi-quantitative visual detection of Cu2+ ion concentrations in water using a portable ultraviolet instrument. The method achieved a minimum detectable concentration of Cu2+ ion as low as 10 μM, surpassing the maximum contaminant level goals of 20.47 μM set by the EPA and the guideline value of 31.47 μM recommended by the WHO. As such, this approach holds promise as a point-of-care testing (POCT) method for Cu2+ ion detection during copper pollution emergency events in water. Additionally, this method can be adapted for the detection of ascorbic acid. Our findings showcase the potential of this dual-modal detection approach, offering a sensitive, rapid, and efficient means for detecting Cu2+ ion, thereby contributing to environmental monitoring and public health applications.

Smartphone-assisted sensing platform based on dual-responsive nitrogen-doped carbon dots for enzyme-free and visual quantitative detection of Cu2+ and glyphosate

Rapid and selective detection of copper ion (Cu2+) and glyphosate (GLY) is crucial to environmental pollution control, especially when using a simple and portable device. In this study, an enzyme-free and visual fluorescence sensor based on nitrogen-doped carbon dots (N-CDs) is successfully designed, featuring strong blue fluorescence and excellent stability. The sensor shows a linear response to Cu2+ over a wide detection range of 0.048 to 40 μM with a low limit of detection (LOD, 48 nM), resulting in fluorescence quenching at 435 nm. Meanwhile, the rapid enhancement in fluorescence intensity of the quenched N-CDs/Cu2+ system can be triggered by GLY owing to the strong complexation between Cu2+ and GLY, with a LOD of GLY as low as 0.24 μM. Furthermore, we develop a smartphone-assisted sensing platform using N-CDs/polyvinyl alcohol films, which captures and analyzes fluorescence images to detect Cu2+ and GLY with sensitive LODs of 73 nM and 0.32 μM, respectively. Satisfactory recoveries, ranging from 94.0 % to 104.6 %, are achieved in real sample detection, implying the potential application in the field of enzyme-free and on-site pesticides detection.

A ratiometric and colorimetric dual-mode fluorescence method for the sensitive determination of copper ion

The present work describes the fabrication of a low-cost, simple, and highly selective analytical method based on the combination of two fluorescent carbon quantum dots (CQDs) for visual or quantitative detection of copper ions at trace levels. Folium cycas and o-phenylenediamine are used as carbon precursors for the preparation of blue fluorescence CQDs (B-CQDs) and yellow fluorescence CQDs (Y-CQDs), respectively. The dual emission ratio fluorescence sensor (B@Y-CQDs), which is obtained through a physical blending method, demonstrates the dual-mode detection of copper ions, including colorimetric detection (visual detection) and ratiometric detection (quantitative detection). Our study reports a portable fluorescent paper sensing platform based on smartphones and computer software that can visually quantify Cu2+ without the need for expensive and bulky laboratory instruments. Upon addition of Cu2+, the simple B@Y-CQDs solution or B@Y-CQDs modified paper-based strip shows a visible color change from blue to yellow under 365 nm ultraviolet light, which achieves visual detection coupled with computer software and smartphones. For the accurate quantitative detection of trace Cu2+, the changes in the fluorescence intensity ratio of F450/550 are recorded, in which B@Y-CQDs exhibited remarkable selectivity and sensitivity, with a low limit of detection (0.73 μM) within the linear ranges of 7–15 μM. The applicability of the sensor is explored by the successful detection of Cu2+ in tap water and rice samples. These results provide a novel strategy for the quantitative and visual detection of various metal ions and hold significant potential for applications in food safety assurance and water pollution control.

High-sensitivity detection of copper ions in water via cellulose nanomaterial nano-antennas and DFT studies

The widespread occurrence of copper in water presents serious health hazards, requiring improvement of a method to monitor and remove copper ions in the field. In this study, a fresh approach is introduced that incorporates Cellulose Nanomaterials (CNMs) with a unique rod-like structure, offering a large surface area that is perfect for adsorbing cupral, a Cu(II) ion probe. By using this arrangement, toxic copper can be rapidly and visibly detected. Without any special tools, it's easy to see the color change from off-white to brown. The copper nano-antenna (CNA) has an impressively high sensitivity, detecting as low as 2.5 × 10–7 M through image analysis and 4.3 × 10–8 M with spectrophotometric methods. The values fall significantly below the WHO drinking water guidelines of 2 ppm. The CNA's ability to detect at low thresholds and be easily regenerated makes it an effective tool for initial water testing. According to the findings, the CNA could be a promising solution for enhancing safety in drinking water by allowing real-time visualization of copper ions, with only 5 mg required for measurements. Computational analysis has been conducted to study the structural properties of copper and its copper complex (Cu(CNA)2). There is a significant-close agreement between the theoretical and experimental results. The developed CNA material was tested in various environmental and real samples for detecting Cu2+ ions, especially in water and whitening cream samples showing the material application for real-world applications.

Development of a two component system based biosensor with high sensitivity for the detection of copper ions

Recent advancements in bacterial two-component systems (TCS) have spurred research into TCS-based biosensors, notably for their signal amplification and broad input responsiveness. The CusRS system in Escherichia coli (E. coli), comprising cusS and cusR genes, is a copper-sensing module in E. coli. However, due to insufficient sensing performance, CusRS-based biosensors often cannot meet practical requirements. To address this issue, we made improvements and innovation from several aspects. CusR and CusS expression were adjusted to enhance the Cu(II) biosensor’s performance. A copy-number inducible plasmid was used for signal amplification, while removing copper detox genes cueO and cusCFBA improved sensitivity and lowered detection limits. Ultimately, in the optimized biosensor of Cu26, the fold-change (I/I0) increased from 1.5-fold to 18-fold at 1 μM, rising to 100-fold after optimizing the cell culture procedure. The biosensor’s high fluorescence enabled rapid, instrument-free detection and an improved analysis strategy reduced the detection limit to 0.01 μM, surpassing traditional methods.

Dual-color fluorescent multi-component hybrid materials for copper ion detection, NADH regeneration and cell imaging

Gold nanoclusters (AuNCs) exhibit unique physical, chemical and photoelectric properties with various advantages. On the other hand, small organic fluorescent molecules show alternative specialized characteristics. To overcome their weaknesses and integrate strengths, we propose here a workable platform to fabricate protein-gold-dye multifunctional hybrid materials. Briefly, protein skeleton bovine serum albumin (BSA), AuNCs, and organic molecule dye Thioflavin T (ThT) are co-assembled mutually to form a dual-color fluorescent material BSA-AuNCs@ThT. This approach is simple, cost-effective, green and environmental friendly. To tackle their biological application, we coat BSA-AuNCs@ThT with cationic polyethyleneimine (PEI). The prepared BSA-AuNCs@ThT@PEI hybrid materials can be used to fluorescence imaging of microbial cells as well as HeLa cells. Due to the unique background of BSA-AuNCs@ThT@PEI, the hybrid materials work well in differentiate heavy metal ions such as Hg2+ and Cu2+ ions. Moreover, this system is also suitable to do the photocatalytic transformation and regeneration of coenzyme NADH. Therefore, we propose this platform to build new nano-dye hybrid materials for copper ion detection, NADH regeneration and cell imaging, or potentially other applications.

Eu-polyaspartic acid based ratiometric fluorescent probes for ultrasensitive and visual detection of tetracycline and copper ions in food samples

The visualization and accurate on-site detection of tetracycline and Cu2+ residues in food are essential for maintaining food safety and public health. A novel poly (aspartic acid) Ratiometric fluorescent probe was designed for the sensitive visual detection of tetracycline (Tc) and Cu2+ using the EDTA-Eu3+ complex as the sensing unit and fluorescein dye as the internal standard. The fluorescence of Eu3+ at 617 nm was turned on significantly by Tc via the “antenna effect” and can be quenched by Cu2+ owing to the inner filter effect. The probes selectively detected Tc and Cu2+ over a wide linear range, low LODs of 10 nM and 333 nM, respectively, were obtained. A smartphone APP and probe-loaded test paper were also assembled into a biomass-based portable sensor for visual point-of-use analysis. The fabricated sensors successfully monitored the Tc and Cu2+ levels in milk, honey, and tap water samples, suggesting their broad applications in food safety monitoring and environmental analysis.

Mandarin Peels-Derived Carbon Dots: A Multifaceted Fluorescent Probe for Cu(II) Detection in Tap and Drinking Water Samples.

Carbon dots (CDs) derived from mandarin peel biochar (MBC) at different pyrolysis temperatures (200, 400, 600, and 800 °C) have been synthesized and characterized. This high-value transformation of waste materials into fluorescent nanoprobes for environmental monitoring represents a step forward towards a circular economy. In this itinerary, CDs produced via one-pot hydrothermal synthesis were utilized for the detection of copper (II) ions. The study looked at the spectroscopic features of biochar-derived CDs. The selectivity of CDs obtained from biochar following carbonization at 400 °C (MBC400-CDs towards various heavy metal ions resulted in considerable fluorescence quenching with copper (II) ions, showcasing their potential as selective detectors. Transmission electron microscopic (TEM) analysis validated the MBC-CDs' consistent spherical shape, with a particle size of <3 nm. The Plackett-Burman Design (PBD) was used to study three elements that influence the F0/F ratio, with the best ratio obtained with a pH of 10, for 10 min, and an aqueous reaction medium. Cu (II) was detected over a dynamic range of 4.9-197.5 μM and limit of detection (LOD) of 0.01 μM. Validation testing proved the accuracy and precision for evaluating tap and mountain waters with great selectivity and no interference from coexisting metal ions.

An interesting aggregation induced red shifted emissive and ESIPT active hydroxycoumarin tagged symmetrical azine: Colorimetric and fluorescent turn on–off–on response towards Cu2+ and Cysteine, real sample analysis and logic gate application

We report a newly synthesized 7-diethylamino-4-hydroxycoumarin tagged symmetrical azine derivative (SHC), with an interesting color transformation from yellowish green to orange via aggregation induced red shifted emissive (117 nm) feature in THF-H2O mixture. Interestingly, the single crystal X-ray analysis of this molecule demonstrates that two hydroxycoumarin moieties were present in azine unit, among them one of the coumarin units was exist as enol form and another one transferred to keto form via ground state proton transfer reaction. The optical responses of the compound in different solvents exposed the observation of dual emissive bands which corresponds to the presence of ESIPT phenomenon in SHC molecule. Further, this characteristic was confirmed by absorption, emission, solid state structure and time resolved fluorescence decay measurements. Furthermore, the fluorophore, SHC was exploited as a colorimetric and turn on–off–on fluorescent probe for detection of Cu2+ ions and Cysteine (Cys). The 1:1 binding ratio of the probe with Cu2+ and Cys with SHC-Cu2+, was established via Job plot analysis, mass spectral technique and the DFT calculations. The probe, SHC was employed for the detection of copper ions in the environmental real water samples. Finally, the reversible fluorescent turn on–off–on character of the probe, SHC was established to construct the IMPLICATION logic gate application.

4-Diphenylaminobenzaldehyde-formulated isonicotinohydrazide for the rapid recognition of Cu2+ ions; Application of RGB tool, pharmaceutical samples, and DFT studies

High copper concentrations have been linked to several harmful illnesses in humans and negatively affect the kidneys and liver. The design and synthesis of simple and effective chemosensors for recognizing copper (Cu2+) ions are extremely significant. However, most of the colorimetric chemosensors have been developed using an intramolecular charge transfer binding mechanism based on donor-acceptor conjugation systems. This study aimed to fabricate a novel Schiff base colorimetric chemosensor, N'-(4-(diphenylamine) benzylidene) isonicotinohydrazide (DPBA-INH), with high sensitivity and selectivity towards copper ions in the semi-aqueous medium (DMSO: H2O, 7:3, v/v). The synthesized receptor DPBA-INH was distinguished using various spectroscopic methods, including NMR analysis, Fourier transform infrared spectroscopy, HRMS, and ultraviolet-visible (UV–vis) spectroscopy. When exposed to sunlight, the receptor DPBA-INH with Cu2+ ion complexation exhibited a color change from orange to pale yellow. A Job's plot and electrospray ionization mass spectra confirmed the presence of complexation at a stoichiometric binding proportion of the receptor to Cu2+ ions of 1:1. The receptor DPBA-INH interacts with Cu2+ ions in a 1:1 stoichiometric manner with a detection limit of 1.40 × 10−7 M. The experimental results were supported by a theoretical DFT study. Moreover, the receptor effectively measured Cu2+ ions in pharmaceutical samples and test strip analyses. Furthermore, the rapid colorimetric recognition of Cu2+ ions in a semi-aqueous medium was achieved using DPBA-INH, which was demonstrated to be an excellent receptor. Notably, DPBA-INH was employed to detect copper ions in real water samples.

Sensing at Your Fingertip: On-Glove Electrochemical Sensor for Copper Detection on Vine Leaves

Intensive use of copper-based pesticides in agriculture can impact human health and biodiversity: the accumulation of this metal in soil negatively affects crop yields. There is growing interest in developing new tools that are capable of monitoring copper occurrence in agricultural contexts through the use of quick and user-friendly approaches for non-specialists, e.g., farmers. This work focuses on the development of a glove-based electrochemical sensor, enhanced with gold nanoparticles, for the detection of copper ions on leaves. The developed device proved was capable of detecting copper ions contained in a copper-based pesticide commonly used in agriculture (Cupravit Bio Advanced). The on-glove analytical device was characterized using garden leaf as the model system and subsequently applied to on-site detection of copper ions on vine leaf treated with Cupravit Bio Advanced. The procedure was very facile: sampling was carried out by touching the leaf with the strip and the stripping-voltammetric measurement was performed by adding a few microliters of an acidic solution to the strip. The on-glove approach allowed evaluation of the level of copper-based pesticide used, avoiding complex and time-consuming tasks. Such operation opens up a wide range of possibilities for improving precision agriculture and sustainable development at the point-of-need for the use of non-specialists.

One-step preparation of orange-red Emitting carbon dots for visual detection of copper ions in the water environment

In this study, p-aminophenol and o-phenylenediamine were used as materials in a straightforward one-step hot solvent approach for generating a nitrogen-doped carbon dot. Fourier Transform Infrared Spectroscopy (FT-IR), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and UV–Vis analysis were used to analyze the resultant CDs composites. Furthermore, fluorescence and absorption spectroscopy were used to assess the optical characteristics. Following the addition of Cu2+, CDs’ fluorescence was quenched statically, resulting in the formation of a non-fluorescent complex. Based on this, a highly selective fluorescent technique was developed with a detection limit of 2.71 μM and a relevant linear range of 10–100 μM for Cu2+. More convenient to carry and detect sodium alginate gel beads doped with carbon dots were prepared for visual detection of Cu2+. Using this method, Cu2+ ions from various environmental sources can be detected rapidly, cheaply, environmentally friendly, and selectively.