Sensor For Cu2 Research Articles

Robust Colorimetric Detection of Cu2+ by Excessed Nucleotide Coordinated Nanozymes

Many sensors for Cu2+ rely on the catalytic activity of Cu2+ to produce a color change, but these colorimetric sensors often suffer from poor selectivity and are susceptible to interference. In this work, we found that Cu2+-catalyzed TMB oxidation can be significantly improved with excessed nucleotides and nucleosides. Especially, with oversaturated guanosine 5′-monophosphate (GMP) to form a coordination nanozyme, the catalytic efficiency was greatly accelerated. It can be attributed to the specific binding between the electron-rich oxygen and nitrogen atoms of guanine with Cu2+. A sensitive and selective strategy for Cu2+ sensing was proposed. Owing to the presence of excessed GMP, it ensures robust activity and less susceptibility to interference. This allowed us to test the sensor in complex samples such as the seawater. This work strongly suggests that by supplying excessed ligands, far exceeding the binding stoichiometry, we may produce more robust sensing systems.

Rare Crystal Structure of Open Spirolactam Ring along with the Closed-Ring Form of a Rhodamine Derivative: Sensing of Cu2+ Ions from Spinach.

Crystal structures of a rhodamine derivative in its closed and open spirolactam ring forms were developed, which allows selective and sensitive detection of Cu2+ ions at a micromolar range in neutral medium. The chemosensing properties of the probe through a pentacoordinate Cu2+ ions were proven by spectroscopic and theoretical analysis. The spirolactam ring opening as the Cu2+ selective sensor was applied to spinach (Spinacia oleracea) to estimate the accumulation of copper as copper(II) in the plant.

A ratiometric fluorescent sensor for tracking Cu(I) fluctuation in endoplasmic reticulum

A two-photon ratiometric fluorescent sensor for Cu+ in endoplasmic reticulum (ER), CNSB , was developed via coumarin/ASBD integration based on FRET mechanism. In solution, CNSB shows reversible, highly-specific ratiometric response to Cu+. Moreover, CNSB exhibits suitable K d value, suggesting the possibility of detecting Cu+ in the living cells. The probe can enter the MCF-7 cells easily and specifically locates in the ER. The highly specific ratiometric response of CNSB toward Cu+ in MCF-7 cells provides the sensor the capacity to visualize both exogenous and endogenous Cu+ in the ER via fluorescence imaging. Next, CNSB was utilized to detect the fluctuation and distribution of Cu+ under ER stress in MCF-7 cells, which confirmed directly the relationship between Cu+ enhancement and ER stress. Meanwhile, the two-photon ability of coumarin facilitated the sensor to visualize Cu+ fluctuation via two-photon fluorescence imaging. In addition, the spatial distribution of Cu+ in the heart slice of the 14-day-old rat was demonstrated using CNSB . This study demonstrates the promising potential of CNSB in clarifying the Cu+-dependent signaling in the ER stress-related diseases.

Thiazoline-pyrene selective and sensitive fluorescence "turn-on" sensor for detection of Cu2.

A thiazoline and pyrene containing sensor 1 was synthesized via one-pot reaction and utilized as a highly selective and sensitive fluorescence "turn-on" sensor for Cu2+ detection, via the fluorescence enhancement of pyrene monomer emission. The 2:1 stoichiometry of 1 and Cu2+ was calculated from Job's plots based on fluorescent titrations, and the complexation of 1 with Cu2+ was also supported by mass spectra, Fourier transform infrared spectra, proton NMR spectra and density functional theory analysis. The fluorescence intensity of 1 at 389 nm and 410 nm increased significantly upon the addition of Cu2+. Limit of detection and association constant value of 1-Cu2+ were calculated using standard deviations and linear fittings, respectively. Results showed that 1 was active for Cu2+ detection in the wide pH range of 2.0-11.0.

Green Silver Nanoparticles Based Multi-Technique Sensor for Environmental Hazardous Cu(II) Ion

In the present work, we report green synthesized unmodified silver nanoparticles from Moringa oleifera’s bark extract (AgNP-MO) as multifunctional sensor for hazardous Cu(II) ion with high selectivity. The optical and fluorescent sensing of Cu(II) ion in presence of AgNP-MO was investigated and optimized. The intensity of SPR absorption band of AgNP-MO dramatically reduced with Cu(II) ion concentration as a result of complex formation, and it could be recognized by naked eye with a visual detection. The electrochemical activity of silver nanoparticles was explored for the sensing of Cu(II) ion by AgNP-MO-modified platinum electrode (AgNP-MO/PE). The Cu(II) ion selectivity of the developed system was investigated by both techniques. The applicability of developed electrochemical sensor was checked with water samples collected from Vembanad Lake, Kumarakom, Kottayam, Kerala, and electroplating industry. The limit of detection of a developed sensor for Cu(II) ion detection was found at 0.530 μM. The antibacterial activity of silver nanoparticles from Moringa oleifera was checked against with two waterborne bacteria extracted from the same lake water sample. To the best of our knowledge, there are no reports for the electrochemical sensing of Cu(II) ion by AgNP-MO/PE. We expect our present approach to have multifunctional applications in various areas.

Turn-off/on fluorescent sensors for Cu2+ and ATP in aqueous solution based on a tetraphenylethylene derivative

Two novel fluorescent sensors based on a tetraphenylethylene derivative (TPE-COOH) were designed and prepared for the rapid detection of cupric ion and adenosine triphosphate (ATP) in 100% aqueous solution.

A dual-mode fluorometric/colorimetric sensor for Cu2+ detection based on hybridized carbon dots and gold-silver core-shell nanoparticles.

A fluorometric and colorimetric dual mode sensing platform based on hybridized carbon dots (Cdots) and gold-silver core-shell nanoparticles (Au@Ag NPs) has been established for the sensitive detection of trace Cu2+ ions in aqueous solution. In this system, the fluorescence of Cdots was quenched by Au@Ag NPs due to the surface plasmon-enhanced energy transfer. Due to the fact that Cu2+ could accelerate the etching process of Au@Ag NPs in the presence of thiosulfate, the fluorescence of Cdots was recovered. The limit of detection (LOD) is 4.81 nM for fluorometric measurements and 3.85 nM for colorimetric measurements. The dynamic range from these two modes is 0.005-1 μM. Importantly, Cu2+ in solution can also be directly visualized by this sensor via evident color change from the solution. Therefore, this dual mode nanosensor has potential applications for the efficient detection of Cu2+ ions in aqueous samples with great selectivity and high sensitivity.

Ratiometric Fluorescence Sensing of Cu(II): Elucidation of FRET Mechanism and Bio‐Imaging Application

AbstractRhodamine‐formylaniline conjugate RFA has been developed as a Cu2+‐selective ratiometric fluorescent probe. The probe shows high selectivity towards Cu2+ ion through both its absorption and emission properties; and has been characterized by 1H NMR, FTIR, ESI‐MS spectroscopy. Sensing of Cu2+ proceed through FRET process which is nicely depicted from steady‐state and fluorescence lifetime studies. From the measurement of fluorescence lifetime, the FRET mechanism has been established undoubtedly. The important parameters regarding FRET, namely the energy transfer efficiency (ΦEt) and the Förster distance (R0) have also been calculated by fluorescence measurement. The origin of different emission bands has been distinguished by recording excitation spectra. The lowest detection limit (DL) for Cu2+ ion was 4.2 ×10−7 M in Tris‐HCl buffered MeCN: H2O (10 mM, 1:1 v/v).

Influence of doping ion, capping agent and pH on the fluorescence properties of zinc sulfide quantum dots: Sensing of Cu2+ and Hg2+ ions and their biocompatibility with cancer and fungal cells.

Herein, a facile one-pot synthetic method was explored for the fabrication of glutathione capped Mn2+ doped‑zinc sulphide quantum dots (GSH-Mn2+-ZnS QDs) for both fluorescent detection of Cu2+ and Hg2+ ions and for fluorescence imaging of two cancer (RIN5F and MDAMB231) and fungal (Rhizopus oryzae) cells. Particularly, doping of Mn2+ into ZnS QDs nanocrystal structure resulted a great improvement in the fluorescence properties of ZnS QDs. The emission peak of undoped ZnS QDs was found at 447 nm, which is due to the large number of surface defects in the ZnS QDs nanostructures. Under identical conditions, there is a good linear relationship between the quenching of fluorescence intensity and analytes (Cu2+ and Hg2+ ions) concentration in the range of 0.005 to 0.2 mM and of 0.025 to 0.4 mM for Cu2+ and Hg2+ ions, respectively. The GSH-Mn2+-ZnS QDs exhibit least cytotoxicity against RIN5F and MDAMB231 cells, demonstrating the multifunctional applications in sensing of metal ions and biocompatibility towards cancer (RIN5F and MDAMB231) and fungal (Rhizopus oryzae) cells.

A selective fluorescent sensor for Cu(II) ion in ethanol and acetone based on BODIPY

A selective fluorescent sensor for Cu(II) ion in ethanol and acetone based on boradiazaindacene (BODIPY) has been studied. The selectivity towards Cu(II) ion is good over Ag(I), Cd(II), Fe(III), Hg(II), Ni(II), Pb(II), and Zn(II) ions, only Fe(III), Hg(II) and Ni(II) ions showed a slight interference. The solution showed strong fluorescence intensity after addition of triethanolamine, indicating that the Sensor 1-Cu(II) complex could be reversed by triethanolamine.

One-pot synthesis of a natural phenol derived fluorescence sensor for Cu(II) and Hg(II) detection

Development of a high performance molecular fluorescence sensor from natural products for metal ions selective detection is also a great challenge. Herein, catechine-dopamine (C-DA) as a fluorescence sensor, was designed for Cu(II) and Hg(II) selective detection in 100% aqueous solution. C-DA with high fluorescence quantum yield of 10.93% was rapidly synthesized from the reaction between two natural phenols, catechine and dopamine, by a simple one-pot organic solvent free approach. Based on fluorescence “on-off”, C-DA could linearly detect the Cu(II) and Hg(II) concentrations in a range of 75 nM - 10 μM and 0.25 μM - 8 μM, respectively, and realized the Cu(II) and Hg(II) determination in tap water samples. Moreover, C-DA exhibited strong affinity to Cu(II) and Hg(II) among 15 kinds of metal ions and 9 kinds of anions. The association constants of C-DA-Cu(II) and C-DA-Hg(II) were respectively calculated as 3.21×104 M-1 and 3.05×104 M-1. Interestingly, although both Cu(II) and Hg(II) formed 1:1 complex to C-DA, they bond to C-DA in a different manner. Cu(II) firstly oxidized the catechol hydroxyl to quinone and was reduced to Cu(I), and then Cu(I) chelated with quinone. Nevertheless, Hg(II) straightly bonded to catechol hydroxyl.

A new colorimetric sensor for visible detection of Cu(II) based on photoreductive ability of quantum dots

Quantum dots (QDs) have been widely used to develop analytical methods due to their unique fluorescent and photoelectrochemical characteristics. However, analytical strategies based on their catalytic property are rarely reported. Here, we demonstrate that the photoreductive ability of QDs can be utilized to develop a sensitive and selective colorimetric sensor for Cu(II). By using UV irradiation, 3,3′,5,5′-tetramethylbenzidine (TMB) is oxidized to its oxidation product, which can be reduced back to TMB by QDs. The presence of Cu(II) decreases the reductive activity of QDs and results in a color change in a signal-on format. The proposed sensor can be activated using a portable UV lamp or direct sunlight. Under optimized conditions, the detection limit (S/N = 3) is 10 nM via spectrophotometry and 0.1 μM by visible color change. This sensing system was applied to quantify Cu(II) in real samples, such as river water and tap water. Results were in agreement with those obtained using inductively coupled plasma spectrometry (ICP). This study may provide new ideas for the development of QD-based sensors.

Rapid Detection of Copper in Biological Systems Using Click Chemistry.

A fast (1 min), straightforward but efficient, click chemistry-based system that enables the rapid detection of free copper (Cu) ions in either biological fluids or living cells without tedious pretreatment is provided. Cu can quickly induce the conjugation between graphene oxide (GO) and a fluorescent dye via click reaction. On the basis of the high specificity of bioorthogonal reaction and the effective quenching ability of GO, the assay studied in this paper can respond to Cu ions in less than 1 min with excellent selectivity and sensitivity, which is the fastest sensor for Cu as far as it is known. In addition, the application of this system is verified by performing assays in living cells and untreated urine samples from patients suffering from Wilson's Disease. Such a Cu detection system shows great promises in both fundamental research and routine clinical diagnostics.

Colourimetric and fluorimetric metal ion chemosensor based on a benzimidazole functionalised Schiff base

Herein we present the interaction of benzimidazole based Schiff base 1 with different metal ions studied by absorption and fluorescence spectroscopies and computational modelling. Compound 1 exhibits changes in spectroscopic properties upon chelation with specific metal ions. Its strong absorption band at 425 nm is significantly red shifted (Δλ = 30 nm) only upon the complexation with Al3+, an effect observable by a naked eye as a colour change from light- to dark-yellow. Of the metal ions investigated, only Al3+ caused any increase in the fluorescence intensity of 1. All other metal ions, including K(I), Na(I), Ag(I), Li(I), Zn(II), Co(II) and Hg(II), showed a negligible fluorescence response, while Cu(II) and Fe(III) significantly decreased the fluorescence intensity. Therefore, system 1 is a promising colourimetric sensor for Al3+, and a fluorescence sensor for Cu2+ and Fe3+ ions. Computational analysis revealed that 1 is unionized in ethanol solution, while it becomes di-deprotonated to 12– upon the complexation with Al3+. This changes the electronic structure of 1 and leaves no acidic hydrogen atoms to allow the ESIPT process. On the other hand, the presence of monovalent metal cations induces only mono-deprotonation to 1–, which turns out to be an insufficient electronic change to be spotted in the recorded spectra.

Synthesis of Dansyl-Substituted Cryptands Containing Triaza­cycloalkane Moieties and their Evaluation as Fluorescent Chemosensors

A method for the synthesis of a new family of cryptands containing 1,4,7-triazacyclononane and 1,5,9-triazacyclododecane moieties and dansyl fluorophore groups has been elaborated starting from free triazacycloalkanes and employing Pd(0)-catalyzed amination at the macrocyclization step. The dependence of the products yields on the nature of reagents has been established. The majority of synthesized macrobicycles have been evaluated as possible chemosensors for detecting metal cations. Compound comprising 1,4,7-triazacyclononane and dioxadiamine linker proved to be a prospective colorimetric sensor for Cu(II) by changing its absorption spectrum in the presence of this cation, while other cryptands demonstrated full quenching of fluorescence in the presence of Cu(II) and Al(III) what makes them promising fluorescent molecular probes for these metals.

Novel synthesis and application of FePt/CuInS2 magneto-optical core-shell nanostructures in copper ions sensing

In this study, the FePt core, CuInS2 shell and FePt/CuInS2 core-shell nanostructures were successfully synthesized using Polyol process. Temperature and field dependence magnetization behavior of as-synthesized FePt and FePt/CuInS2 showed super paramagnetic and ferromagnetic behavior at 300K, respectively. The blocking temperature (TB) estimating by the peak in ZFC curve was about 26K for FePt and this peak was absences for FePt/CuInS2 NSs, which indicates ferromagnetic regime. To design novel sensor for Cu+2 ions, a glassy carbon electrode was fabricated with FePt/CuInS2 core shell NSs and multi walled carbon nanotubes (MWCNT). Using cyclic voltammetry, the electrochemical behavior of Cu+2 ions was studied at FePt/CuInS2 core-shell/MWCNT@GCE and compared with responses on bare GCE and MWCNT@GCE. Finally, this electrode was used for construction of the calibration curve in linear range from 12.5–575.0nmolL−1 Cu+2 with a detection limit of 0.14nmolL−1.

A new Schiff base as a turn‐off fluorescent sensor for Cu2+ and its photophysical properties

A new Schiff base receptor 1 was synthesized and its photophysical properties were investigated by absorption, emission and excitation techniques. Furthermore, its chromogenic and fluorogenic sensing abilities towards various metal ions were examined. Receptor 1 selectively detects Cu2+ ion through fluorescence quenching and detection was not inhibited in the presence of other metal ions. From fluorescence titration, the limit of detection of receptor 1 as a fluorescent 'turn-off' sensor for the analysis of Cu2+ was estimated to be 0.35μM.

A novel, highly sensitive, selective, reversible and turn-on chemi-sensor based on Schiff base for rapid detection of Cu(II)

In this work, a novel optical fluoro-chemisensor was designed and synthesized for copper (II) ions detection. The sensor film is created by embedded N,N-Bis(2-hydroxo-5-bromobenzyl)ethylenediamine in poly vinyl chloride (PVC) film in presence of dioctyl phthalate (DOP) as plasticizer. The receptor Schiff base reveals “off-on” mode with high selectivity, significant sensitivity to Cu(II) ions. The selectivity of optical sensor for Cu(II) ions is the result of chelation enhanced fluorescence (CHEF). The optimal conditions of pH and response time at which higher efficiency of sensor film is performed was found to be 6.8 and 2.48min. The possible interference of other metal ions in solution was examined in presence of different types of metal ions. This film shows high selectivity and ultra-sensitivity with low detection limit LOD (1.1×10−8M). Thus, these considerable properties make it viable to monitor copper metal ions within very low concentration range (0–15×10−6M Cu(II)) and highly selective even in the presence of different types of metal ions. The sensor reversibility was achieved by utilizing EDTA solution with concentration of 0.1M solution.

CNT-anchored cellulose fluorescent nanofiber membranes as a fluorescence sensor for Cu2+ and Cr3+

1,4-Dihydroxyanthraquinone (1,4-DHAQ, a fluorophore) doped carbon nanotubes@cellulose (1,4-DHAQ-doped CNTs@CL) nanofibrous membranes have been prepared via electrospinning and subsequent deacetylation in this work.

A novel hexahydroquinazolin-2-amine-based fluorescence sensor for Cu2+ from isolongifolanone and its biological applications

The isolongifolanone derivative (2c) exhibit highly selective and sensitive fluorescence quenching towards copper ions, and this was used for real-time sensing of cooper ions in vivo.