Detection Of Copper Ions Research Articles

A dual-channel sensing platform for the cross-interference-free detection of tetracycline and copper ion

Tetracycline (TC) and copper ion (Cu2+), as important additives in animal feed, play a crucial role in disease prevention and growth regulation. However, the abuse leads to concentration accumulation, which seriously threatens human health and the ecological environment. There is an urgent need to develop a detection method to achieve fast and synchronous detection of these pollutants without cross-interference. Here, a carbon dots-doped lanthanide-based fluorescent nanosensor (CDs@Tb-MOFs@SiO2–NH2-Eu) was synthesized, which can detect TC in the 380 nm channel by “antenna effect” and internal filtering effects (IFE), and identify Cu2+ in the 320 nm channel. The sensor was highly sensitive to TC within 0–4 μM with a detection limit as low as 3.64 nM, and Cu2+ could be detected within 0–40 μM with a detection limit of 38 nM. A portable dual-channel visual fluorescence sensor was obtained by loading the probes onto test paper and cotton swabs in food samples, which indicates the practicability of this sensing strategy.

A 1,8-Naphthalimide-based Tripodal Fluorescent Chemosensor to Selectively Detect Copper Ions.

A 1,8-naphthalimide-based tripodal fluorescent ligand (L3) was synthesized through the copper (I) catalyzed Huisgen azide-alkyne cycloaddition reaction of 2-(2-azidoethyl)-6-morpholino-1H-benzo[de]isoquinoline-1,3(2H)-dione with triproparagylamine. Naphthalimide acts as the fluorophore while the triazole and amine nitrogens chelate the metal ion. L3 showed a selective fluorescence turn-off for Cu(II) over other metal ions in aqueous acetonitrile solution. A Job's plot, Benesi-Hildbrand plot and high-resolution mass spectrometry data confirm a 1:1 binding stoichiometry with a binding constant of 7.8 х105 M- 1 while addition of disodium EDTA demonstrates its reversibility. The structure and stability of the complex was supported by theoretical calculations. The limit of detection for Cu(II) was calculated to be 0.3 µM which is considerably lower than WHO recommended Cu(II) limit in drinking water.

Highly selective and sensitive colorimetric chemosensor using PVA/chitosan ion-imprinted nanofibers for copper ion detection and removal

Herein, a highly efficient colorimetric chemosensor incorporating ion-imprinted electrospun nanofiber was developed for the removal and detection of Cu2+ ions. In this regard, PVA/chitosan composites were used as the polymeric matrix, and 1-(2-pyridylazo)-2-naphthol was employed for complex formation. The prepared naked-eye sensor was characterized using Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, scanning electron microscopy, atomic force microscopy, differential scanning calorimetry, thermogravimetric analysis, and X-ray diffraction analysis, revealing the morphological, structural, and molecular properties of the sensor.The results showed that the colorimetric chemosensor based on copper-imprinted nanofiber (Cu–INF) possesses higher selectivity for Cu2+ compared to interference ions. The selectivity coefficient (k) and relative selectivity coefficient (K′) indicated the selective behavior of Cu–INF in the adsorption of Cu2+ in binary systems including Cu2+/Co2+, Cu2+/Ni2+, and Cu2+/Zn2+.Furthermore, the ion-imprinted nanofiber was used for the preconcentration of copper ions, demonstrating a high adsorption capacity of 128.205 mg g−1 for Cu2+. The equilibrium adsorption isotherm and adsorption kinetics of Cu2+ on Cu–INF followed the Freundlich adsorption isotherm and a pseudo-second-order model, respectively. The developed sensor exhibited a linear detection range of 5 × 10−8 - 2 × 10−7 M with a limit of detection (LOD) of 1.07 × 10−8 M for copper ions. The results indicated satisfactory adsorption and successful detection of Cu2+ at trace concentrations.

Dual signal amplification sensor based on imprint-modified DNA for high-sensitivity detection of copper ions

In order to improve the sensitivity of ion imprinted electrochemical (IIE) sensor to detect copper ions, a novel dual signal amplification (DSA) sensor was proposed using deoxyribonucleic acid (DNA) modified IIE sensor. Chitosan (CS) was used as a functional monomer for IIE sensor. The IIE sensor was prepared by mixing copper ion templates with CS and removing the templates. Gold nanoparticles (AuNPs) were electrodeposited onto the surface of IIE sensor to improve their conductivity and provide a connecting platform for DNA probes. And then the DNA probe was fixed on the surface of AuNPs to prepare a DSA sensor. The signal of DSA sensor was significantly amplified by the synergistic effect of IIE sensor and DNA probe. The feasibility, parameter optimization and electrochemical performance were analyzed by experimental comparison, surface micro scanning and kinetic study. The results show that compared with IIE sensor, the sensitivity of DSA sensor is significantly improved, with a value of 1.6712 × 10-6 A·(µM)-1. The exchange current density is 5.9765 × 10-8 A·cm−2. The detection range is 10 nM to 100 nM (R2 = 0.99651) with the detection limit of 4.17 nM (3σ/slope). The recommended method has high sensitivity and selectivity, as well as very high recovery rates in tap water and milk.

A Fluorescent Probe Derived from L‐Tryptophan for Copper (II) Ion Detection in Aqueous Media

AbstractCopper (Cu2+) is a transition metal ion extensively distributed in numerous foodstuffs of both animals and vegetables. An excess intake of Cu2+ ions cause injury, pneumonitis, a disorder in the nervous system, and gastrointestinal problems. Hence, we have developed a simple and novel Schiff base‐based fluorescence sensor for the detection of Cu2+ ions. The sensor, ‐3‐(1H‐indol‐3‐yl)‐2‐((4‐nitrobenzylidene) amino)propanoic acid (INAP), was synthesized from tryptophan and nitrobenzaldehyde by the reflux method and characterized by various analytical methods. The prepared INAP acted as a chemical sensor and displayed outstanding sensitivity and choosiness characteristics for Cu2+ ions an aqueous solvent. In the presence of Cu2+, it demonstrated a fluorescence change in an aqueous medium with a “turn‐off” phenomenon via complex‐mediated energy transfer characteristics, and the method of continuous variation suggested a 1 : 2 complex formation of the metal ion with INAP. The LOD of the sensor system was calculated to be 1.3 μM for the Cu2+ ion. In addition, the INAP fluorescent probe was applied to tap water samples and found acceptable recoveries. These results suggest that the newly fabricated sensor system would be explored as a chemosensor for the recognition of Cu2+ ions in environmental samples.

Nitrogen–silicon Co-doped carbon dots synthesized based on lemon peel for copper (II) detection via a dynamic quenching mechanism

As a metal, copper plays an important role in biological systems. However, excessive intake can lead to toxicity and disease. Therefore, there is a need to establish accurate and sensitive methods to detect and monitor copper levels in food and the environment. Herein, nitrogen-silicon co-doped carbon dots (N,Si-CDs) were synthesized using lemon peel as the biomass precursor by one-step hydrothermal synthesis with the addition of citric acid solution and 3-aminopropyl triethoxysilane (APTES). The prepared N,Si-CDs showed excellent photobleaching resistance, brilliant fluorescence performance and good selectivity. The experiments showed that the fluorescence of N,Si-CDs decreased after the interaction of N,Si-CDs with copper ions. Further studies showed that the decrease in fluorescence intensity of the fluorescent probe due to Cu2+ was dynamic quenching. In addition, the fluorescence intensity of N,Si-CDs showed a good linear relationship with the concentration of copper ions. The linear range was 0.5 μM–250 μM, the R2 was 0.995, and the limit of detection was 0.43 μM. Finally, the method has been successfully applied to the detection of copper ions in the water environment and food, and the recoveries of 99.4%–102.1 % were obtained, which indicated that the method had a promising future.

A Terbium Ion-Based Dual-Ligand Fluorescent Probe for Highly Selective and Sensitive Detection of Cu2+ Ions.

In this study, a fluorescent probe (GMP-Tb-SSA) utilizing lanthanide coordination polymer nanoparticles, GMP-Tb, as a sensing platform, and 5-sulfosalicylic acid (SSA) as a cofactor ligand was proposed for the detection of copper ions (Cu2+). GMP-Tb was synthesized by the self-assembly of guanine monophosphate (GMP) and terbium ion (Tb3+), and SSA was introduced as a sensitizer into the GMP-Tb network. Cu2+ could efficiently inhibit the electron transfer from the ligand GMP to the central ion, Tb3+, leading to a significant quench of fluorescence of Tb3+. The method is highly selective with a linear range of 0 to 21 µM and a detection limit of 300 nM. It is not interfered by metal ions, amino acids, and other species, and can be successfully applied to the detection of Cu2+ in real water samples.

A novel dual channel six-membered spirorhodamine for Cu2+ and ClO- depending on solvent and application in real samples and bioimaging

To reveal the solvent dependence of six-membered rhodamine spirocycles (SMRS), a new probe SM-RB has been synthesized and investigated the spectral properties in different solvents upon the addition of various metal ions and anions. SM-RB exhibited high selectivity for Cu2+ in CH3CN/HEPES and ClO- in C2H5OH/HEPES solutions, respectively. The spectral changes of SM-RB in the presence of ClO- in C2H5OH/HEPES solution were much less than that of Cu2+ in CH3CN/HEPES. The detection limit of Cu2+ was as low as 36 nM (fl) in CH3CN/HEPES. The kinetic equilibration time (8 s) indicated that the two solvent systems did not delay the spectral response speed to Cu2+ and ClO-. Solvent systems influenced the pKa value of SM-RB in CH3CN/HEPES and C2H5OH/HEPES. The pKa value of SM-RB was 4.34 (±0.7) (Abs) and 4.75 (±0.14) (Fl) in CH3CN/H2O, but can’t be exactly calculated by pH titration in C2H5OH/H2O. The reversibility and Job plot of SM-RB were investigated to propose the response mechanism of SM-RB with Cu2+ and ClO- in the two solvent systems. Finally, SM-RB not only can be used for the quantitative detection of copper ions in grape peel, but also can real-time monitor the fluctuation of Cu2+ in lysosomal pools.

Synthesis and characterization of new 4-amino-5-methyl-4H-1,2,4-triazole-3-thiol (MMTP) Schiff base for spectrophotometric detection of iron(III) and copper(II) ions in laboratory and different water samples: A biological and molecular docking exploration

New spectrophotometric techniques were introduced for the determination of Fe(III) and Cu(II) in many different analyzed samples. The concentrations of Fe(III) and Cu(II) ions were measured in the existence of a novel Schiff base (Z)-6-(3-mercapto-5-methyl-4H-1,2,4-triazol-4-ylimino)-2-thioxotetrahydropyrimidin-4(1H)-one (MMTP). The new chelates were formed rapidly at the room temperature at 510 and 550 nm in presence of triton X-100 and CPB surfactants for Fe(III) and Cu(II), respectively. Linear calibrated graphs were obtained at concentration ranges of 1.0–130 µg mL-1 for Fe(III) and 0.5–90 µg mL-1 for Cu(II). LOD were calculated to be 1.05, 1.98 µg mL-1 and LOQ were 3.18 and 6.02 µg mL-1 for Fe(III) and Cu(II), respectively. A large number of foreign ions were not interfering in the present method. The stoichiometric composition of the chelates was studied by molar ratio and job´s methods to be found 1:2 (metal ion: ligand) ratio. The Fe(III) and Cu(II) solid chelates were prepared and characterized using IR, UV–Vis., 1HNMR , 13CNMR TG-DTG, and XRD spectroscopy. The IR spectral revealed that MMTP chelated as a bidentate ligand via NO atoms. Thermal analysis revealed the decomposition mechanism of MMTP and its chelates. A suggested octahedral geometry encompasses all of the chelates. The UV–visible spectra and magnetic moment analyses confirm the octahedral geometrical geometries. The band gap (Eg) values are 1.53 and 1.56 for Fe(III) and Cu(II) respectively. The smallest band gaps imply that these chelates are semiconductors belonging to solar materials. The in-vitro antioxidant activity of the individual chelates was evaluated using the DPPH radical scavenging assay. All compounds showed antioxidant activity with IC50 values of 0.316, 0.186 and 0.124 mg/mL for MMTP, Fe(III) and Cu(II), respectively. MMTP and its chelates were tested for their antimicrobial activity against various types of bacteria and fungi using the disc diffusion method. The Cu(II) complex showed the greatest biological activity.

Construction of a portable copper ion detection method based on colorimetric fluorescent probe and its application in food and organisms

In the subject of food safety, identifying and measuring the active components in food is a hot topic. Food safety and biological health are all strongly correlated with the amount of copper ions (Cu2+) presented in the environment. Nevertheless, the existing Cu2+ detection technology has disadvantages such as difficult operation and inconvenient on-site analysis. Therefore, a new Cu2+ fluorescent probe RH-Cu with a fast response and low limit of detection was built in this study. It can be used to measure the quantity of Cu2+ in real food and water samples. Additionally, a relationship was established between the color RGB values and the concentration of Cu2+. A new mobile phone software (Pick RGB) was developed to realize the portable detection of Cu2+. This work offers a portable instrument for the detection of Cu2+ and provides an idea for developing portable detection techniques for other significant foods’ active constituents.

O-215 Copper oxide nanoparticles (CuONPs) impairs mitophagy and promotes DNA methylation to suppress mouse embryonic pluripotency

Abstract Study question Does exposure to copper oxide nanoparticle (CuONPs) have adverse effects on early embryonic development? What is the potential mechanism? Summary answer CuONPs exposure can damage mitophagy and lead to α-KG reduction, resulting DNA hypermethylation, thereby reducing the pluripotency of pre-implantation embryos in mice. What is known already Environmental nanomaterials contamination is a great concern for organisms including human. Exposure to nanomaterials have been associated with fecundity and fertility in couples conceiving via assisted reproduction technology. Among these bio-effects, nanomaterials induced epigenetic changes are of particular interest. Copper oxide nanoparticles (CuONPs) are widely used in a huge range of applications which might pose potential risk to organisms. Recent studies reported that CuONPs exposure resulted in transgenerational toxicity in Caenorhabditis elegans associated with possible epigenetic regulation. However, whether CuONPs exposure affect mammalian embryonic development, and if so the underlying mechanisms, are unclear. Study design, size, duration For the human experiments, we measured the copper ion content in women’s urine, and assessed the expression of pluripotent genes in 3PN embryos treated with CuONPs. For the embryo experiments, we collected zygotes from ICR mice and cultured them in KSOM medium with CuONPs (10 μg/mL) until blastocyst stage. For the cell experiments, we treated mouse embryonic stem cells (mESCs) with CuONPs (2 μg/mL) for four days to detect cell proliferation and pluripotency. Participants/materials, setting, methods The ICP-MS method was used to detect copper ion content in women’s urine. Time–lapse incubator was used to document the developmental potential of embryos. To quantify the metabolites of embryo, we employed metabolomics. Single-cell multiomics sequencing that enables profiling of genome-wide chromatin accessibility, DNA methylation and RNA expression were performed to detect genes expression and epigenetic modification. We used real-time PCR, immunofluorescence, and western blot to measure the expression of pluripotency related genes. Main results and the role of chance In human, we discovered a significant negative relationship between the urine’s copper ion content and clinical pregnancy rate. In embryo experiments, CuONPs exposure has been shown to have adverse effects on embryo developmental potential, resulting morula and blastocyst transformation arrest, as well as reduction in blastocyst rate and live birth rate. Furthermore, CuONPs treatment led to a reduction in blastocyst quality, indicating a decrease in blastocyst cell count, particularly in ICM cells. CuONPs also inhibited the pluripotency of blastocysts and mESCs, showing down-regulated expression of pluripotent genes. Mechanistically, CuONPs aggregated in lysosomes and decreased the mitophagic flux of embryos, which caused damaged mitochondria to accumulate and ultimately caused mitochondrial dysfunction. Notably, in embryos treated with CuONPs, there was a decrease in α-ketoglutarate (α-KG) due to the disruption of the tricarboxylic acid (TCA) cycle. α-KG is an essential cofactor for α-KG dependent dioxygenases such as the ten-eleven translocation (TET) family of DNA demethylase. The lack of α-KG in CuONPs-treated embryos led to DNA hypermethylation, which reduced chromatin accessibility, and suppressed the expression of pluripotent genes like sox2, klf2, and klf4. The poor pluripotency ultimately leads to abnormal embryonic development in CuONPs-treated embryos. Limitations, reasons for caution The molecular mechanism by which CuONPs arrest the development of pre-implantation embryos remains to be determined. In addition, future work should be extended to human embryos to determine whether this mechanism is conserved between mice and humans. Wider implications of the findings The findings of this work indicated the relationship between CuONPs and epigenetic modification. The results will support a more thorough understanding into the biosafety of CuONPs, and offer fresh perspectives on the potential uses of nanomaterials in the field of reproductive medicine in the future. Trial registration number Not Applicable

A dual responsive bis-thiophene affixed thiosemicarbazide based chemosensor for colorimetrically Hg2+ and fluorometrically Cu2+ ions and their applications in live cell imaging

In this work, we developed a fast and straightforward colorimetric and photoluminescent chemosensor probe (P1), featuring bis-thiophene-thiosemicarbazide moieties as its signaling and binding unit. This probe exhibited rapid sensitivity to Hg2+ and Cu2+ ions in a semi-aqueous medium, resulting in distinct colorimetric and photoluminescent changes. In the presence of Cu2+, P1 displayed an impressive 50-fold increase in photoluminescence (PL) at 450 nm (with excitation at 365 nm). The probe P1 formed a 1:1 complex with Hg2+ and Cu2+ ions, featuring association constant values of 4.04 × 104 M−1 and 1.25 × 103 M−1, respectively. P1 has demonstrated its efficacy in the analysis of real samples, yielding promising results. Additionally, the probe successfully visualized copper ions on a mouse fibroblast cell line (NIH3T3), highlighting its potential as an intracellular probe for copper ion detection.

Single-atom iron nanoatalysts facilitate electrochemiluminescence of graphitic carbon nitride for copper ion sensing

As an emerging electrochemiluminescence (ECL) nanomaterial, graphitic carbon nitride (g-C3N4) has attracted considerable attention from the scientific community due to its excellent optical properties, favorable biocompatibility, and tunable bandgap structure. However, the ECL intensity of g-C3N4 is subject to various influencing factors, including conductivity and electrode passivation, which pose notable challenges in improving its ECL performance. In this study, iron single atom nanocatalysts (Fe SAC) were introduced onto g-C3N4 sheets, and a novel approach was proposed to enhance the active sites, modulate the bandgap, and bolster the conductivity through synergistic mechanism. Furthermore, Fe SAC acted as the co-reactant promoter, amplifying the ECL signal significantly. Comparative analysis revealed a visible improvement in the ECL performance of Fe SAC-g-C3N4/K2S2O8 in a potential range of 0 to −0.9 V. Via the electron transfer strategy, a copper ion-sensitive ECL sensor based on Fe SAC-g-C3N4 was developed with the linear range of 0.01–100 μM and a detection limit of 0.75 nM. This sensor has been successfully applied in detecting copper ions in water environment and human serum samples, providing a new strategy for enhancing the ECL performance of g-C3N4 and expanding the utility of Fe SAC in ECL.

Benzidine-based chemosensors for the selective detection of phosphate, carbonate and copper ions: Applications in water and food sample analysis and on-field detection kit

In this work, benzidine-based chemosensors were synthesized. A5R1 had a cage-like structure along with 2-OH binding sites for encapsulation of Cu2+, A5R2 was found to bind with PO43¯ and CO32¯ ion; whereas A5R3 was innocent towards any cations or anions. The LOD for A5R1 with Cu2+ was found to be 2.63 ppm. A5R2 detected PO43¯ and CO32¯ with limit of detections 4.13 ppm and 5.40 ppm respectively. The interference studies indicated that there was no other ion which could restrain the analysis. Job’s Plots showcased the 1:2 binding of the receptors with the analyte ion(s). The practical applicability of the probes was demonstrated by on-field detection kit and test-strip fabrication with colour change chart. Logic gate formulation with active simulation governed by the reversibility studies envisaged the reversibility and reusability of the probe and its solicitation in making electric devices. Furthermore, spiking studies proved the application of the receptors for convenient analyte detection in real-life food and water samples.

Voltammetric co-determination of lead and copper in gunshot residue based on iron oxide particle/spent coffee grounds-modified electrode.

A novel electrochemical sensor was developed for the detection of lead (Pb) and copper (Cu) ions using spent coffee grounds decorated with iron oxide particles (FeO/SCG). The FeO-decorated SCG was used to modify a glassy carbon electrode (GCE). FeO, SCG, and FeO/SCG were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The electrochemical properties of the modified electrode were characterized by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The electrode modifications increased theactive surface area and electron transfer and enhanced the accumulation of the target analyte. In the optimal condition, the developed sensor showed linear ranges of 1.0µg L-1-0.05mg L-1 and 0.05mg L-1-0.8mg L-1 for Pb2+ and 5.0µg L-1-0.1mg L-1 and 0.1mg L-1-0.8mg L-1 for Cu2+. The limit of detection (LOD) was 1.0µg L-1 for Pb2+ and 2.4µg L-1 for Cu2+. The developed sensor was successfully applied to determine Pb2+ and Cu2+ in bullet holes. The results were in good agreement with those obtained by inductively coupled plasma optical emission spectrometry (ICP/OES).

Electrochemiluminescence Sensor Based on TPEA‐RuMOF: For Highly Selective and Sensitive Detection of Copper Ions

AbstractIn this study, we present the novel combination of AE‐TPEA with RuMOF to construct an electrochemiluminescence (ECL) sensor using a TPEA‐RuMOF composite material specifically for copper ions (Cu2+) detection. Using K2S2O8 as a co‐reactant, we explored the ECL behavior of the TPEA‐RuMOF modified electrode, enabling the quantitative detection of Cu2+. Remarkably, this sensor exhibited a wide linear range from 1×10−5 to 1×10−9 M (R2=0.998) and boasted a detection limit as low as 0.41 nM, which is considerably below the EPA (Environmental Protection Agency) permissible copper ion concentration in drinking water of <1.3 mg/L. our synthesized probe offers enhanced stability and selectivity in copper ion detection. This indicates its considerable potential for high‐performance copper ion detectors. We further validated the analytical applicability of this sensor using river water samples.

Synthesis of Phenol-Hydrazide-Appended Tetraphenylethenes as Novel On-Off-On Cascade Sensors of Copper and Glutathione.

This study reports the synthesis of novel fluorescent probes, phenol-hydrazide-appended tetraphenylethenes (TPEs I and II), and explores their photochemical properties. The probes exhibit aggregation-induced emission (AIE) in increasing water content, as observed using fluorescence spectroscopy. Further investigation with UV-vis and fluorescence techniques revealed their potential as ion sensors. Both TPE I and TPE II act as "turn-off" sensors for Cu2+ ions, showing decreased fluorescence intensity in their presence. Their limit of detection (LOD) and association constant (K a) for Cu2+ were found to be comparable at 747 nM/597 nM, and 2.46 × 105 M-1/2/1.78 × 105 M-1/2, respectively. Moreover, the quantum yields of TPE I and TPE II were also calculated and found to be 0.651 and 0.325, respectively. Interestingly, these probes also function as "turn-on" sensors for glutathione (GSH) in the presence of copper. This means their fluorescence can be reversibly switched off and on by alternating CuCl2 and GSH additions. Moreover, the LOD values for GSH with TPE II-Cu2+ were calculated to be 544 nM. In addition, the investigation also employed visual analysis to assess the color alterations of TPEs on filter paper and in real water samples. Overall, this research introduces promising new probes with potential applications in copper ion detection and biomolecule glutathione sensing in real water samples.

Synthesis and dual sensing of vanadium and copper ions using protein capped selenium nanoparticles

Highly homogenous and spherical shaped Selenium nanoparticles with an average size of 20 nm were synthesized from an eco-friendly and environmentally safe approach using bovine milk protein casein as stabilizing agent (named as CasSeNPs). Protein functionalization provided excellent stability at variable temperatures (25–60 °C), pH (8–10), ionic strength (0.05–2 M), and storage period for more than five months. Synthesized CasSeNPs were extensively characterized using various spectroscopic (UV–visible, Fourier transform infrared (FTIR), circular dichroism (CD), intrinsic fluorescence spectroscopy), particle sizing (dynamic light scattering (DLS) and zeta potential), microscopic (scanning electron microscopy, energy dispersive X-ray spectroscopy (SEM/EDS), atomic force microscopy (AFM)), and X-ray diffraction (XRD) measurements. Moreover, CasSeNPs was established as highly sensitive and selective sensor for the simultaneous detection of vanadium (V+2) and copper (Cu+2) ions with significant linearity (0.5–10 and 0.1–1.0 µM, respectively), detection limits (LOD = 0.03 and 0.067 µM, respectively), and percent recoveries (94–105 %) in real environmental (tap water) and biological (human plasma and urine) samples with adequate test performance. Cumulatively, obtained results revealed that the established very simple, biocompatible and economical nanosensor has great potential for applications in analytical chemistry as well as for biological investigations.

Mg/S@g-C3N4 nanosheets: A promising fluorescence sensor for selective Cu2+ detection in water

This work describes the development of a novel fluorescence sensor based on magnesium/S@g-C3N4 nanosheets for selective detection of copper (Cu2+) ions in water. Mg/S@g-C3N4 nanosheets were prepared by the polycondensation technique and investigated by X-ray diffraction (XRD), ATR-FTIR spectroscopy, scanning electron microscopy (SEM), surface area (BET), and UV–Vis optical absorption measurements. XRD and ATR-FTIR analysis showed the characteristic peaks for S@g-C3N4. The broad full width at half maximum (0.056 radians) implies a smaller crystallite size, representing smaller Mg/S@g-C3N4 sheets. SEM micrograph showed non-exfoliated nanosheets with flake-like structures. The EDS mapping confirmed the presence of magnesium, carbon, nitrogen, and sulfur throughout the nanosheets. The Mg/S@g-C3N4 nanosheets possess a high surface area of 40 m2/g and mesopores within the nanosheets, with a size of 1.57 nm. The band gap of the Mg/S@g-C3N4 nanosheet was estimated to be 3.0 eV. The sensor exhibits a strong quenching response towards Cu2+ ions, with a decrease in fluorescence intensity as the concentration of Cu2+ increased from 1 μM to 20 μM. The Stern-Volmer quenching constant (KSV) showed a relatively high value of 185053 M−1. The estimated value of LOD by the Mg/S@g-C3N4 sensor for Cu2+ was 16.2 nM. The sensor offered high sensitivity and selectivity for Cu2+ detection over other heavy metals.

Protein-Labeling Reagents Selectively Activated by Copper(I).

Copper is an essential trace element that participates in many biological processes through its unique redox cycling between cuprous (Cu+) and cupric (Cu2+) oxidation states. To elucidate the biological functions of copper, chemical biology tools that enable selective visualization and detection of copper ions and proteins in copper-rich environments are required. Herein, we describe the design of Cu+-responsive reagents based on a conditional protein labeling strategy. Upon binding Cu+, the probes generated quinone methide via oxidative bond cleavage, which allowed covalent labeling of surrounding proteins with high Cu+ selectivity. Using gel- and imaging-based analyses, the best-performing probe successfully detected changes in the concentration of labile Cu+ in living cells. Moreover, conditional proteomics analysis suggested intramitochondrial Cu+ accumulation in cells undergoing cuproptosis. Our results highlight the power of Cu+-responsive protein labeling in providing insights into the molecular mechanisms of Cu+ metabolism and homeostasis.