Sensitive Detection Of Copper Ions Research Articles

An array of femtoliter wells for sensitive detection of copper using click chemistry

Sensitive detection of copper ion (Cu2+), which is of great importance for environmental pollution and human health, is crucial. In this study, we present a highly sensitive method for measuring Cu2+ in an array of femtoliter wells. In brief, magnetic beads (MBs) modified with alkyne groups were bound to the azide groups of biotin-PEG3-azide (bio-PEG-N3) via Cu+-catalyzed click chemistry. Cu+ in the click chemistry reaction was generated by reducing Cu2+ with sodium ascorbate. Following the ligation, the surface of the MBs was modified with biotin, which could be labeled with streptavidin-β-galactosidase (SβG). The MBs complex was then suspended in β-galactosidase substrate fluorescein-di-β-d-galactopyranoside (FDG), and loaded into the array of femtoliter wells. The MBs sank into the wells due to gravity, and the resulting fluorescent product, generated from the reaction between SβG on the surface of the MBs and FDG, was confined within the wells. The number of fluorescent wells increased with higher Cu2+ concentrations. The bright-field and fluorescent images of the wells were acquired using an inverted fluorescent microscope. The detection limit of this assay for Cu2+ was 1 nM without signal amplification, which was 103 times lower than that of traditional fluorescence detection assays.

DNA-modified Prussian blue nanozymes for enhanced electrochemical biosensing.

Prussian blue nanoparticles exhibit the potential to be employed in bioanalytical applications due to their robust stability, peroxidase-like catalytic functionality, straightforward synthesis, and biocompatibility. An efficient approach is presented for the synthesis of nucleic acid-modified Prussian blue nanoparticles (DNA-PBNPs), utilizing nanoparticle porosity to adsorb nucleic acids (polyT). This strategic adsorption leads to the exposure of nucleic acid sequences on the particle surface while retaining catalytic activity. DNA-PBNPs further couple with functional nucleic acid sequences and aptamers through complementary base pairing to act as transducers in biosensors and amplify signal acquisition. Subsequently, we integrated a copper ion-dependent DNAzyme (Cu2+-DNAzyme) and a vascular endothelial growth factor aptamer (VEGF aptamer) onto screen-printed electrodes to serve as recognition elements for analytes. Significantly, our approach leverages DNA-PBNPs as a superior alternative to traditional enzyme-linked antibodies in electrochemical biosensors, thereby enhancing both the efficiency and adaptability of these devices. Our study conclusively demonstrates the application of DNA-PBNPs in two different biosensing paradigms: the sensitive detection of copper ions and vascular endothelial growth factor (VEGF). These results indicate the promising potential of DNA-modified Prussian blue nanoparticles in advancing bioanalytical sensing technologies.

Porphyrin Functionalized Carbon Quantum Dots for Enhanced Electrochemiluminescence and Sensitive Detection of Cu2.

Porphyrin (TMPyP) functionalized carbon quantum dots (CQDs-TMPyP), a novel and efficient carbon nanocomposite material, were developed as a novel luminescent material, which could be very useful for the sensitive detection of copper ions in the Cu2+ quenching luminescence of functionalized carbon quantum dots. Therefore, we constructed a sensitive "signal off" ECL biosensor for the detection of Cu2+. This sensor can sensitively respond to copper ions in the range of 10 nM to 10 μM, and the detection limit is 2.78 nM. At the same time, it has good selectivity and stability and a benign response in complex systems. With excellent properties, this proposed ECL biosensor provides an efficient and ultrasensitive method for Cu2+ detection.

CdSe/ZnS QDs embedded polyethersulfone fluorescence composite membrane for sensitive detection of copper ions in various drinks

The copper ion was detected rapidly by a novel sensing membrane in this paper for its damage to health and the environment. CdSe/ZnS QDs modified polyethersulfone membrane (QDs@PESM) was made by phase-inversion method using a membrane separation technique and quantum dots (QDs). When the sample passed through the membrane, the copper ions in the sample caused the membrane’s fluorescence to be quenched. The fluorescence quenching value of the membrane is used to calculate the concentration of copper ions. With R 2= 0.9964, Cu2+could be quantitatively detected over a wide concentration range (10–1000 μg/L). The method’s LOD and LOQ were 4.27 and 14.23 μg/L, respectively. When the CdSe/ZnS QDs@PESM was used to analyze Cu2+ in various real drinks, including well water, baijiu, orange juice, beer, and milk, the recovery ranged from 79.1 to 123.9%, indicating that the CdSe/ZnS QDs@PESM can be used as a rapid, simple and reliable method to determine Cu2+ in various matrices.

Construction of a novel fluorescent DNA aptasensor for the fast-response and sensitive detection of copper ions in industrial sewage.

Heavy metal pollution poses a great threat to the ecological environment and human health. In particular, copper ions (Cu2+) play a vital role in regulating fundamental life behavior, and the homeostasis of Cu2+ is closely related to many physiological processes. The excessive accumulation of Cu2+ in the human body through food and drinking water will cause severe diseases. However, current conventional Cu2+ detection methods for evaluating the content of Cu2+ are unable to meet the complete requirements of practical Cu2+ analysis in the practical aquatic environment. In this work, we successfully constructed a novel fluorescent DNA aptasensor, which originated from the binding reaction between the improved DNA fluorescent light-up aptamer termed S2T3AT-GC and a small fluorescent molecule termed DFHBI-1T (S2T3AT-GC/DFHBI-1T) to realize fast and anti-interference response for Cu2+via the competitive interaction between Cu2+ and S2T3AT-GC (Cu2+/S2T3AT-GC) destroying the contained G-quadruplex structure of S2T3AT-GC. Moreover, it enables the sensitive detection of Cu2+ with a detection limit of 0.3 μM and a wide detection linear range from 0.3 to 300 μM. Moreover, with the verification of high stability in real industrial sewage samples, this aptasensor exhibits excellent detection performance for Cu2+ analysis in real water samples. Therefore, the proposed aptasensor exhibits great potential in exploring Cu2+-related environmental and ecological research.

A squaraine-based colorimetric probe for the sensitive detection of copper ion (II)

A squaraine based colorimetric probe 2,4-bis[4-(N,N-diisobutylamino)-2,6-dihydroxyphenyl]squaraine (IHSQ) was selected for colorimetric detection of Cu2+ and the characteristics of IHSQ for Cu2+ recognition were investigated by absorption spectra. The results showed the absorbance of IHSQ significantly decreased with increasing concentration of Cu2+ in acetonitrile/H2O (V/V = 9/1). This colorimetric detection method shows a satisfactory linear response (R2 = 0.9856) to Cu2+ concentration within the range from 2 μM to 200 μM. The limit of detection was 2 μM which was much lower than the environmental protection agency guideline of China (15.63 μM) in drinking water. Moreover, no obvious interference was observed on the detection of the Cu2+ in the presence of the common metal ions such as Zn2+, K+, Ca2+, Na+, Co2+, Ba2+, Cd2+, Cr3+, Sr2+, Pb2+ and Fe3+, indicating that IHSQ possesses high selectivity and satisfactory sensitivity for the detection of Cu2+.

Encapsulating gold nanoclusters into metal–organic frameworks to boost luminescence for sensitive detection of copper ions and organophosphorus pesticides

Gold nanoclusters (Au NCs) with luminescence property are emerging as promising candidates in fluorescent methods for monitoring contaminants, but low luminescence efficiency hampers their extensive applications. Herein, GSH-Au NCs@ZIF-8 was designed by encapsulating GSH-Au NCs with AIE effect into metal-organic frameworks, achieving high luminescence efficiency and good stability through the confinement effect of ZIF-8. Accordingly, a fluorescent sensing platform was constructed for the sensitive detection of copper ions (Cu2+) and organophosphorus pesticides (OPs). Firstly, the as-prepared GSH-Au NCs@ZIF-8 could strongly accumulate Cu2+ due to the adsorption property of MOFs, accompanied by a significant fluorescence quenching effect with a low detection limit of 0.016 μM for Cu2+. Besides, thiocholine (Tch), the hydrolysis product of acetylthiocholine (ATch) by acetylcholinesterase (AchE), could coordinate with Cu2+ by sulfhydryl groups (-SH), leading to a significant fluorescence recovery, which was further used for the quantification of OPs owing to its inhibition to AChE activity. Furthermore, a hydrogel sensor was explored to accomplish equipment-free, visual, and quantitative monitoring of Cu2+ and OPs by a smartphone sensing platform. Overall, this work provides an effective and universal strategy for enhancing the luminescence efficiency and stability of Au NCs, which would greatly promote their applications in contaminants monitoring.

Resonance Rayleigh scattering method for highly sensitive detection of copper ions in water based on salicylaldeoxime-copper (Ⅱ)- 2-methylimidazole supramolecular

In weakly acidic BR buffer solution, a convenient and sensitive resonance Rayleigh scattering (RRS) method for the detection of Cu(Ⅱ) was developed based on the formation of salicylaloxime-Cu(Ⅱ) supramolecular complex by complexation reaction. The coordination reaction of salicylaldehyde oxime with Cu(Ⅱ) led to the significant enhancement of the resonance Rayleigh scattering intensity of the solution, and the increase of the resonance Rayleigh scattering intensity was proportional to the concentration of Cu (Ⅱ). When organic compounds with different molecular structures were introduced into the system, the resonant Rayleigh scattering intensity of the solution system changed differently. The interaction between the compounds and the spatial structure of the complexes were characterized by transmission electron microscopy (TEM), Fourier real-time infrared spectroscopy (FT-IR), zeta potential and particle size. The results showed that when 2-methylimidazole was introduced, the layered texture of Cu(Ⅱ)-CH3COO--H2PO4- -salicylaldoxime system changed to porous reticular spatial structure, and the RRS value increased significantly. Under the optimal conditions, in the range extending from 0.08 to 2.81 µmol/L, the equation of linear regression was ΔI = 3202c + 10.88 (c, µmol/L) with a correlation coefficient 0.9996, and the detection limit was estimated to be 4.23 × 10-2 µmol/L. The method was successfully applied for the determination of Cu(Ⅱ) in tap and river water sample, suggesting its great potential toward Cu(Ⅱ) analysis.

Dual-emission fluorescent nanoprobe based on Ag nanoclusters for sensitive detection of Cu(II)

Noble metal nanoclusters have attracted much attention because of their excellent fluorescence properties. In this work, we demonstrated a dual-emission fluorescent nanocomposite based on silver nanoclusters. First, we synthesized positively charged His-AgNCs, which emits intense blue light, and then Ag nanoclusters with stable red emission were synthesized using DHLA as the ligand. Thus a dual-emission fluorescent nanoprobe was successfully obtained through electrostatic self-assembly, with the advantages of good water solubility and excellent stability. Based on the intensity ratio of the two emission peaks, the nanoprobe can be used for selective and sensitive detection of copper ions, and presents a good linear relationship within a certain concentration range. In addition, we also designed a polymer film, and our dual-emission nanoprobe was successfully loaded onto it, which means that the visual detection of copper ions is possible. This indicates that our dual-emission fluorescent nanoprobe has potential application prospects in environmental analysis, medical diagnosis, biological detection, etc.

Chemiluminescence of doped carbon dots with H2O2-KMnO4 system for the detection of Cu2+ and tannin

The carbon dots doped with chlorine and phosphorus (CDs-Cl,P) were used as chemiluminescence (CL) reagent for the sensitive detection of copper ions (Cu2+) and tannin (TA). The CDs-Cl,P was found to strongly enhance the reaction of H2O2 and KMnO4 in alkaline medium. The enhanced CL behavior of CDs-Cl,P was investigated and it was found that some radicals such as •OH, •O2– and 1O2 appeared in the CL reaction process. The participation of Cu2+ could result in an enhanced CL intensity of the CDs-Cl,P-H2O2-KMnO4 system due to the Cu2+-catalyzed decomposition of H2O2 resulting in more •OH generation. Therefore, the CDs-Cl,P-H2O2-KMnO4 system was used to selectively quantify Cu2+ in solution by CL emission. A linear increase was observed between CL intensity and Cu2+ concentration. The CDs-Cl,P-H2O2-KMnO4 system allowed the detection of Cu2+ down to lower concentration of 0.1 μM with a linear range of 0.2–60.0 μM. Moreover, TA as a common polyphenolic compound, could selectively decrease the CL signal of the CDs-Cl,P-H2O2-KMnO4-Cu2+ system due to its complexation with Cu2+. On this basis, the CL assay for TA was also developed. The detection limit was 0.14 μM and the linear range was from 5.0 μM to 100.0 μM. The proposed method was successfully applied to the determination of Cu2+ and TA in water, rice dumplings leaves, sodium copper chlorophyllin and wine samples with satisfactory results.

Ionothermal synthesis of carbon dots from cellulose in deep eutectic solvent: A sensitive probe for detecting Cu2+ and glutathione with “off-on” pattern

Highly sensitive detection of metal ions and biothiols is very important for environment-friendly and human health but under great challenges of high-cost and complex experimental operation. In this work, we reported a simple and effective ionothermal method for the synthesis of nitrogen and sulfur doped carbon dots (N, S-CDs) from cellulose, which can be used as an on–off fluorescent sensor for the sensitive detection of copper ions (Cu2+) and glutathione (GSH). In this process, cellulose was used as a renewable carbon source, and deep eutectic solvent (DES) prepared by urea/sulfamic acid was used as a green solvent and nitrogen sulfur dopant. The as-prepared CDs have excellent optical properties, pH resistance, excellent photostability and hydrophilicity, with a quantum yield (QY) of 7.17% and the fluorescence intensity of the CDs still reached 85% of the initial intensity after 50 days. The fluorescent probe can selectively detect Cu2+ with a high sensitivity of 23.4 nM. In addition, the addition of GSH can restore the fluorescence of CDs by forming a more stable Cu2+-GSH complex. Therefore, the CDs-Cu2+ complex can be used as a secondary sensor with a detection range of 5.98 μM.

A Facile Colorimetric Method for Ultra-rapid and Sensitive Detection of Copper Ions in Water

It is of great meaning to develop a facile, reliable and sensitive method to detect copper ions in water. In the study, a facile method has been developed for rapid and sensitive detection of Cu2+. An interesting phenomenon has been observed that 3,3′,5,5′-tetramethylbenzidine (TMB) ethanol solution can be extremely fast passed from colorless to yellow once Cu2+ ions are added. It easily occurs to us that Cu2+ can be quantitatively determined via the absorbance at 904 nm of the color changed TMB solution. More importantly, some specific anions (Cl−, Br−) can significantly enhance the absorption intensity. Under the optimized experimental conditions, this method exhibits a good linear response range for Cu2+ from 0.5 to 100 μM, with the detection limit of 93 nM. Moreover, the possible detection principle has been explored. It is worth mentioning that the color change can be clearly observed by naked eyes for the detection of 1 μM Cu2+, which is far below the threshold limit of Cu2+ in drinking water suggested by World Health Organization. It means that this method possess great promise for on-site Cu2+ detection.

A new spiropyran compound for selective naked-eye detection of copper ions in aqueous media and on test paper strips

Using a strategy of modifying a bis(pyridin-2-ylmethyl) amino group in the 5-position, a new spiropyran dye ((1′-ethyl-3′,3′-dimethyl-N, N-bis(pyridin-2-ylmethyl) was synthesized. The dye was able to distinguish copper ions with remarkable selectivity by naked eye on paper strips and in aqueous media. Copper ions are selectively coupled to the receptor, which stimulates the opening of the spirocycle. Consequently, the π -electrons are localized on the spiropyran and a new absorption peak appears between 450 and 600 nm. Due to its functional properties, the receptor facilitates the rapid, selective, and sensitive detection of copper ions with a detection limit of 19 nM. According to Job's plot analysis, the correlation ratio between the probe and copper ions appears to be 2:1. Further, the probe was successfully applied to test papers strips that demonstrated distinct colors changes in response to different concentrations of copper ions.

Resonance Rayleigh Scattering Method for Highly Sensitive Detection of Copper Ions in Water Based on Salicylaldeoxime-Copper (Ii) - 2-Methylimidazole Supramolecular

Resonance Rayleigh Scattering Method for Highly Sensitive Detection of Copper Ions in Water Based on Salicylaldeoxime-Copper (Ii) - 2-Methylimidazole Supramolecular

Development of an impedimetric sensor based on carbon dots and chitosan nanocomposite modified electrode for Cu(II) detection in water

The fast and sensitive detection of copper ions would be essential for water monitoring. Herein, we report a novel development of an impedimetric sensor based on carbon dots/chitosan nanocomposite. Carbon dots (CDs) were synthesized by simple heating of an acidic aqueous solution of glucose. The prepared CDs were characterized by TEM, FTIR, XRD, UV-visible, and PL. These measurements revealed that the CDs possess a mean size of 3.2 nm, a graphitic structure with carboxyl and hydroxyl groups on the surface, and shows particular optical properties. A glassy carbon electrode (GCE) was modified with a carbon dot/chitosan nanocomposite and was characterized by scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). The CDs-CHITO/GCE electrode exhibits a large surface area, good conductivity film, and charge transfer at film/electrolyte interface. The proposed impedimetric sensor exhibits a linear response to Cu(II) ranging from 10−9 M to 10−5 M with a detection limit about 5 × 10−10 M. In addition, the sensor shows a good selectivity toward Cu(II) ions, which is less than 5%. Therefore, the as-developed impedimetric sensor exhibits good reproducibility, stability, selectivity, and a low limit of detection, which augur well for its application in water safety control processes.

Electroanalytical Sensor Based on Gold-Nanoparticle-Decorated Paper for Sensitive Detection of Copper Ions in Sweat and Serum.

The growth of (bio)sensors in analytical chemistry is mainly attributable to the development of affordable, effective, portable, and user-friendly analytical tools. In the field of sensors, paper-based devices are gaining a relevant position for their outstanding features including foldability, ease of use, and instrument-free microfluidics. Herein, a multifarious use of filter paper to detect copper ions in bodily fluids is reported by exploiting this eco-friendly material to (i) synthesize AuNPs without the use of reductants and/or external stimuli, (ii) print the electrodes, (iii) load the reagents for the assay, (iv) filter the gross impurities, and (v) preconcentrate the target analyte. Copper ions were detected down to 3 ppb with a linearity up to 400 ppb in standard solutions. The applicability in biological matrices, namely, sweat and serum, was demonstrated by recovery studies and by analyzing these biofluids with the paper-based platform and the reference method (atomic absorption spectroscopy), demonstrating satisfactory accuracy of the novel eco-designed analytical tool.

Highly Sensitive Detection of Copper Ions by Reduced Glutathione Modified Gold Nanocluster Fluorescence Sensor

Highly Sensitive Detection of Copper Ions by Reduced Glutathione Modified Gold Nanocluster Fluorescence Sensor

New Schiff Base as Selective and Sensitive Detection of Copper Ions in Aqueous Solvent

AbstractDetection of metals in aqueous solution is advantageous in the field of food, nutrition and drug chemistry. Hence, a new sensor was designed for the selective and sensitive detection of Cu2+ ions in the aqueous media. Herein, Schiff base L=(E)‐N′‐((1H‐indol‐2‐yl)methylene)isonicotinohydrazide acts as a sensor which consist of isaniazid and indole moiety connected with azomethine linkage. Single crystal X ray analysis along with other spectroscopic methods was used to confirm the structure of the synthesized ligand. Theoretical calculations were performed which gave satisfactory correlation with experimental results. A naked eye color change from colorless to yellow was observed upon addition of Cu(II) ions in synthesized Schiff base sensor. UV‐Visible absorption spectroscopy was used for the further sensing experiments and a red shift of 63 nm was observed only in the case of Copper ions in a pH range of 6–8, this confirms the selective nature of Schiff base sensor towards the Cu2+ ions. Negligible interference of other metal ions in the sensing of copper ions was confirmed by interference study.Calculated limit of detection for copper detection in aqueous media was 0.05 μM. To check the practical applications of the studied Schiff base as a chemosensor, test strips test was also performed.

A new colorimetric and fluorescent chemosensor based on thiazolyl-hydrazone for sensitive detection of copper ions

A Cu2+-specific chemosensor probe thiazolyl-hydrazone (BL) has been designed and prepared, which provide tridentate chelate NNO coordination mode for Cu2+ with binding stoichiometry of 1:1. The BL solution exhibits a rapid color change from colorless to yellow along with a new intense absorption band at 414 nm upon binding to Cu2+ cation, whereas other metal cations do not induce such a change. The analytical detection limit is 0.75 μM, and the naked eye detection limit is as low as 20 μM. Additionally, the emission signal of BL could be quenched by Cu2+ and Fe3+ with a detection limit of 7.2 μM and 4.3 μM, respectively.

Multisensing Capability of MoSe2 Quantum Dots by Tuning Surface Functional Groups

Several distinct surface-functionalized molybdenum diselenide (MoSe2) quantum dots (QDs) were developed as chemosensors based on the fluorescent probe. The carboxylic-, amine-, and thiol-functionalized MoSe2 QDs (MoSe2/COOH, MoSe2/NH2, and MoSe2/SH) were synthesized by tuning their surface with thiol-containing capping agents. These MoSe2/COOH and MoSe2/NH2 QD sensors were implemented for the highly selective and sensitive detection of copper ion (Cu2+) and 2,4,6-trinitrophenol (TNP) with a lower detection limit of 4.6 and 45.3 nM, respectively. Similarly, the MoSe2/SH QDs while coupled with gold nanoparticles showed excellent selectivity toward melamine (MA) with a lower detection limit of 27.7 nM. It is surprising to find that each functionalized QD exhibits a distinct sensing mechanism in the detection of Cu2+, TNP, and MA, based on metal-ion-induced fluorescence turn-on, electron transfer, and energy transfer suppression, respectively. Moreover, these MoSe2 QD-based chemosensors were successfully util...