Search Results (511)

Disulfiram (DSF), long used as an aversive agent in alcohol dependence therapy, has recently regained attention as a promising candidate for oncological drug repurposing. After administration, DSF is rapidly reduced to diethyldithiocarbamate (DDC), which, in the presence of Cu²⁺, forms the complex Cu(DDC)₂. This compound acts as a strong inducer of oxidative stress, an inhibitor of the ubiquitin–proteasome system, and a suppressor of endogenous hydrogen sulfide (H₂S) synthesis. DSF also modifies protein and non-protein thiol groups, disrupting cancer cell metabolism and promoting apoptosis. Despite robust preclinical evidence, clinical translation remains limited. Key obstacles include DSF’s rapid metabolism, insufficient availability of free copper ions in humans, and the lack of predictive biomarkers capable of identifying responsive patients. Another challenge is DSF’s low oral bioavailability, which prevents the drug from reaching tumor tissue at therapeutically effective concentrations. Consequently, current research focuses on advanced nanocarrier systems designed to protect DSF from premature degradation and ensure its controlled release within the tumor microenvironment. This review summarizes the multifaceted anticancer mechanisms of DSF and discusses biological and pharmacological factors underlying the discrepancies between experimental findings and clinical outcomes. Full article

Ergothioneine (ESH) is one of the most abundant antioxidants in the human body, but its biological functions remain unclear. In this work, we elucidated the detailed mechanism of the deactivation of divalent copper ions Cu(II) by ESH using optical spectroscopy, NMR, and LC-MS. We found that the reduction of Cu(II) ions to Cu(I) by ESH occurs in a bimolecular reaction of Cu^II(ES⁻)₂ complexes, leading to the formation of the disulfide ESSE. Cu(I) ions remain bound in stable complexes with ESH, preventing their reactions with molecular oxygen. Over longer timescales, ESSE decomposes, regenerating reduced ESH and forming the final reaction product, hercynine (EH). The conversion of one ESH molecule to EH causes the reduction of four Cu(II) ions. We determined the rate constants of the bimolecular reaction between Cu^II(ES⁻)₂ complexes to be k₃ = (8 ± 4) × 10⁴ M⁻¹s⁻¹ and of ESSE hydrolysis to be k₄ = (1.7 ± 0.4) × 10⁻⁵ s⁻¹ and also estimated the formation constant K₁₂ ≈ 1.2 × 10¹⁷ M⁻² for the Cu^II(ES⁻)₂ complex. The high efficiency of Cu(II) reduction and the chelation of the resulting Cu(I) ions in a stable complex supports the hypothesis that protecting cells from oxidation by metal ions is likely one of the main functions of ESH. Full article

Copper is an essential trace element that plays critical roles in enzymatic processes and cellular metabolism. However, excessive exposure to its ions can lead to toxicity through oxidative stress mechanisms. Therefore, the chemical ‘speciation’ of copper(II) ions (Cu(II)) in biological fluids such as saliva is of critical importance. However, currently this phenomenon remains poorly understood, despite its importance for our understanding of bioavailability, toxicity, and sensory perception. Therefore, this study employed ¹H nuclear magnetic resonance (NMR) spectroscopy, Fourier-transform infrared attenuated total reflectance (FTIR-ATR) spectroscopy, and scanning electron microscopy (SEM) to investigate the molecular nature and complexation characteristics of low-molecular-mass Cu(II) complexes formed in human whole mouth salivary supernatant (WMSS) samples. Findings obtained revealed that Cu(II) ions form distinct complexes with salivary biomolecules, particularly amino acids such as histidine and glutamine, aromatic metabolites, proteins, and further small organic biomolecules, e.g., carboxylic acid anions. These results provide new insights into copper speciation in the oral cavity, with implications for dietary Cu(II) ion availability, metallic taste perception, and potential toxicological risks associated with elevated oral exposure levels. Full article

A simple and cost-effective graphite paste electrode modified with 5-(4-aminophenyl)-4-amino-1,2,4-triazole-3(2H)-thione was developed for the selective voltammetric determination of Cu(II) ions in environmental water samples. The N,S-donor ligand was incorporated into a graphite–polystyrene matrix without the use of nanomaterials, providing a reproducible and straightforward electrode fabrication route. Scanning electron microscopy revealed a rough, porous surface morphology with an enhanced electroactive surface area of 0.065 cm², approximately twice the geometric area. Electrochemical impedance spectroscopy confirmed diffusion-controlled mass transport, while cyclic voltammetry indicated quasi-reversible behaviour of the Cu(II)/Cu(0) redox system with a linear dependence of peak current on the square root of the scan rate. Differential pulse voltammetry under optimised conditions (0.1 mol·L⁻¹ H₂SO₄, pH 1.0–1.2) yielded a linear analytical response over the concentration range of 0.01–0.4 μmol·L⁻¹ (R² = 0.99507), with a limit of detection of 0.02 μmol·L⁻¹ and a limit of quantification of 0.06 μmol·L⁻¹—well below the WHO guideline for copper in drinking water. The sensing mechanism involves selective N,S-bidentate coordination of Cu(II) at the electrode surface, followed by electrochemical reduction, as supported by FT-IR spectroscopic evidence. The sensor demonstrated good selectivity toward Cu(II) in the presence of common interfering metal ions at up to 20-fold excess. The method was successfully validated against ICP-OES (recovery 99.8%, RSD < 0.33%) and confirmed by spike–recovery experiments (99.0–99.5%), confirming its practical applicability for trace-level environmental monitoring. The modified electrode retained approximately 93% of its initial response after 30 consecutive measurements and 91% after 14 days of storage, demonstrating good operational stability. Full article

Earlier work by some of the present authors identified power-law statistical regularities across the periodic table: a near-Zipf relationship $W\propto Z^{1.09}$ between atomic weight and atomic number in neutral atoms, and a fine-structure splitting scaling $\Delta E\propto Z^{1.78}$ in the $3d^{2+}$ (Cr-like) isoelectronic sequence of highly charged ions (HCIs). The apparent tension between this superlinear empirical exponent and the linear-in-Z scaling derived analytically by Lyu, Keitel, and Harman for relativistic clock-state transitions in $n{d}^6$ ions is resolved by writing the scaling law in the form $\Delta E=A{(Z-Z^{\ast })}^{\gamma }$, which gives $\gamma =1.03$ and $Z^{\ast }=25.83$ for the $3d^{2+}$ data and restores a near-Zipf interpretation. We extend the thresholded model from the single $3d^{2+}$ sequence to fourteen isoelectronic sequences spanning C-like ($Z\ge 6$) through Mo-like ($Z\ge 42$), drawing on the NIST Atomic Spectra Database, evaluated compilations of strontium, copper, and tungsten ion data, and digitization of GRASP MCDHF Mo-like results. Comparing the fitted threshold $Z^{\ast }$ against the classical Slater shielding ${\sigma }_{\mathrm{Slater}}$ of the valence shell reveals three regimes: (i) Coulomb-LS sequences (C/N/O/Ne-like) with $Z^{\ast }$ fixed at zero by construction; (ii) a mainstream cluster of nine sequences (a mix of spin–orbit fine-structure and, for the $d^2$ Ca-/Sr-like members, Coulomb term separations) for which $Z^{\ast }$ tracks ${\sigma }_{\mathrm{Slater}}$ within $\pm 1.5$ units; (iii) a pair of $n{d}^6{}^{5}D_0$ sequences (Cr-like $3d^6$ and Mo-like $4d^6$) with $Z^{\ast }-{\sigma }_{\mathrm{Slater}}=+7.20$ and $+10.36$, scaling linearly with Z in the jj regime (after resolving a low-Z LS–jj crossover for the Mo-like member). The slope ratio $A_{\mathrm{Mo}}/A_{\mathrm{Cr}}\approx 0.48$ is of the order of the hydrogenoid radial-extent ratio $⟨r^2⟩(3d)/⟨r^2⟩(4d)\approx 0.32$, exceeding it by ∼50% as expected from relativistic $4d$ contraction. A falsifiable extrapolation for the W-like $5d^6{}^{5}D_0$ sequence is offered: $\Delta \in [+7,+11]$, $A_W\in [0.12,0.18]$ eV/Z, with explicit failure modes specified for an independent GRASP MCDHF test. Full article

A novel carbohydrazide-based ligand (L) and its binuclear Cu(II) complex were successfully synthesized and characterized. Structural analysis confirmed that the Cu(II) complex adopted a monoclinic crystal system with a distorted coordination configuration, in which the multidentate Schiff base ligand chelated and bridged two Cu(II) centers. The in vitro anti-tumor results revealed that the Cu(II) complex exhibited prominent cytotoxicity against five human cancer cell lines with much lower IC₅₀ values than the free ligand, copper chloride and cisplatin. Mechanistic studies demonstrated that the Cu(II) complex significantly increased intracellular ROS and MDA levels, decreased the GSH/GSSG ratio, and reduced ATP content, thereby disrupting cellular redox balance and bioenergetic metabolism. In addition, flow cytometry analysis verified that the complex effectively triggered tumor cell apoptosis. In contrast, free CuCl₂ showed almost no anticancer activity, indicating that the synergistic effect between the Schiff base ligand and copper ions contributed to the excellent anti-tumor performance. This work suggests that the prepared binuclear Cu(II) complex can serve as a promising candidate for developing metal-based anticancer agents. Full article

The present study reports the application of a gold microelectrode array to determine copper(II) ions by anodic stripping voltammetry (ASV). The microelectrode characterization of the presented working electrode was investigated. Moreover, the way of its preparation ensures its reusability and eco-friendly character, thanks to the use of environmentally benign electrode material. The procedure does not require modification of the surface of the working electrode. Main experimental parameters were optimized, including pH and a concentration of the supporting electrolyte, activation and deposition conditions, and square wave parameters. The calibration graph was linear in the range of Cu(II) concentrations from 2 × 10⁻⁹ to 2 × 10⁻⁷ mol L⁻¹ (with a deposition time of 30 s) and from 5 × 10⁻¹⁰ to 5 × 10⁻⁸ mol L⁻¹ (with a deposition time of 90 s; RSD was 4.7% (n = 3) for a 1 × 10⁻⁸ mol L⁻¹ of Cu(II)). The limit of detection was equal to 1.93 × 10⁻¹⁰ mol L⁻¹ (t_acc = 90 s). The correctness of the developed procedure was successfully checked by analysis of certified reference material and a tap water sample, confirming the possibility of its practical application. Satisfactory recovery values were also obtained during the analysis of an environmental water sample. Full article

A sustainable alginate-based composite adsorbent was developed by valorizing soy whey wastewater for the efficient removal of copper (II) ions from aqueous solutions. Soy whey wastewater/sodium alginate/cellulose (SWWSAC) beads were fabricated via a controlled slow-release calcium ion cross-linking strategy. This strategy resulted in homogeneous gelation, effective encapsulation of wastewater-derived organics and the formation of a hierarchical mesoporous structure. Compared with pure sodium alginate (SA) and sodium alginate–cellulose (SAC) beads, the SWWSAC beads exhibited a significantly higher specific surface area (3.95 m²/g) and pore volume (0.021 cm³/g), thus having markedly enhanced copper (II) ion adsorption performance. Batch adsorption experiments demonstrate that the adsorption process was strongly dependent on solution pH, adsorbent dosage, contact time and initial metal concentration. Kinetic analysis indicates that the adsorption process followed a pseudo-second-order model, while equilibrium data were well described by the Langmuir isotherm, corresponding to monolayer chemisorption. Based on this isotherm, SWWSAC beads had a theoretical maximum adsorption capacity of 168.3 mg/g (25 °C), 190.8 mg/g (35 °C), and 204.4 mg/g (45 °C). Thermodynamic results reveal that the adsorption was spontaneous and endothermic. FTIR and XPS analyses confirm that copper (II) ion removal was governed by synergistic complexation involving carboxyl, hydroxyl, carbonyl, and protein-derived nitrogen-containing functional groups. Moreover, the SWWSAC beads had a copper (II) ion removal efficiency of (92.4 ± 0.4)% and retained 73.3% of their initial adsorption capacity after six regeneration cycles in actual electroplating wastewater treatment. In this process, the beads exhibited good anti-interference performance against coexisting cations and good structural stability. Therefore, this work demonstrates an effective and low-cost strategy for copper (II) ion removal while providing a value-added route for the sustainable utilization of soy whey wastewater. Full article

Although amorphous calcium phosphate (ACP) has been extensively employed as a biomaterial in dental and orthopedic fields, its exploration for environmental applications—particularly in potentially toxic element remediation—remains notably limited in the scientific literature. This study reports the rational design of a multifunctional adsorbent by integrating sodium citrate-stabilized ACP (Cit-ACP) nanoparticles into calcium-crosslinked sodium alginate (SA) hydrogel beads for selective Cu²⁺ sequestration from aqueous systems. Comprehensive sorption assessments revealed that equilibrium uptake aligned with the Freundlich isotherm (indicating heterogeneous surface interactions), while kinetic profiles adhered to pseudo-second-order behavior, characteristic of chemisorption-driven processes. Under optimized operational parameters (pH 5.0, 45 °C), the Cit-ACP/SA composite attained an exceptional maximum adsorption amount of 307.76 mg/g. Thermodynamic analysis further confirmed the spontaneity (ΔG° < 0) and endothermic nature (ΔH° > 0) of the process. Multi-technique characterization (XPS, FTIR, XRD, pH trajectory) elucidated a dual-mode adsorption mechanism: (i) ion exchange between aqueous Cu²⁺ and structural Ca²⁺ within both the alginate matrix and ACP framework; and (ii) in situ surface precipitation yielding copper-substituted hydroxyapatite. Owing to its facile aqueous-phase synthesis, superior adsorption performance, biodegradability, macroscopic bead morphology enabling rapid separation, and robust selectivity in complex matrices, the Cit-ACP/SA composite presents a sustainable, scalable, and eco-compatible platform for practical remediation of copper-contaminated wastewater. Full article

Moxifloxacin-based Schiff-base ligands provide a useful platform for tuning the coordination and biological properties of fluoroquinolone derivatives. Here, a moxifloxacin–salicylaldehyde hydrazone ligand (MOX-S) was prepared and coordinated with cobalt(II), nickel(II), copper(II), oxovanadium(IV), and gadolinium(III) ions to obtain a series of metal complexes. Citrate-stabilized gold nanoparticles (AuNPs) were also prepared and functionalized with MOX-S and the Cu(II) complex to evaluate the effect of nanoformulation on biological performance. The compounds were characterized using complementary analytical, spectroscopic, magnetic, thermal, and microscopic techniques. The combined data support 1:2 metal-to-ligand formulations for the complexes and indicate coordination mainly through the azomethine nitrogen and oxygen donor sites of MOX-S. In antimicrobial screening, the activity was strongly metal- and organism-dependent. Cu–MOX-S and VO–MOX-S showed the most pronounced activity against Gram-positive bacteria, with inhibition zones of up to 30 mm, while Cu–MOX-S displayed MIC values of 19.53 and 39.06 µg mL⁻¹ against Bacillus subtilis and Staphylococcus aureus, respectively. Cytotoxicity assays showed that MOX-S was more active than moxifloxacin against MCF-7 and HepG2 cells, while Cu–MOX-S showed enhanced potency, particularly toward HepG2 cells, with an IC₅₀ of 0.98 µM and a selectivity index of 5.97. AuNP formulations further increased the apparent antiproliferative potency in the tested cancer cell lines, giving sub-micromolar IC₅₀ values. Computational analyses, including DFT-based electronic descriptors and molecular docking, provided qualitative support for the experimentally observed coordination and cytotoxicity trends. Overall, metal coordination and AuNP formulations provide complementary strategies for modulating the physicochemical and in vitro biological behavior of this moxifloxacin-derived hydrazone scaffold. Full article

Copper is an indispensable trace element for maintaining metabolic homeostasis; however, the dysregulation and subsequent accumulation of Cu²⁺ are critically linked to neurodegenerative pathologies, including Alzheimer’s disease in humans. Consequently, the development of robust analytical tools for Cu²⁺ monitoring is of paramount importance. Here, we report a 2,2′-dipicolylamine porphyrin (DPAP)-based fluorescent sensor designed for the precise detection of metal cations. Photophysical investigations reveal that DPAP operates via a rapid turn-off fluorescence mechanism, achieving high-performance sensing in the parts-per-million range. Notably, the probe demonstrates exceptional sensitivity with detection limits of 26.3 nM for Cu²⁺ and 34.8 nM for Ni²⁺. Interference studies demonstrated the selectivity of DPAP for Cu²⁺ over a diverse range of competing metal ions such as Na⁺, Ag⁺, Ni²⁺, Cr³⁺, Pb²⁺, Al³⁺, Fe²⁺, Cd²⁺, and Zn²⁺. These results indicate that DPAP is a sensitive and selective probe suitable for copper ion detection. Full article

Chitosan-based copper composites have attracted considerable interest for biomedical and antimicrobial uses due to their biocompatibility, adjustable dielectric characteristics, and ion-mediated antimicrobial effectiveness. In this study, chitosan films doped with Cu(NO₃)₂, containing 3, 6, and 9 wt% of copper nitrate were produced using a solution-casting method at room temperature. This was done to explore the relationship between structural interactions, dielectric relaxation, optical properties, and antimicrobial efficacy. The resulting composite has been investigated physically using FTIR, XRD, optical analysis, and dielectric spectroscopy, and biologically for its antimicrobial activity. FTIR revealed the molecular structure of Cs-Cu(NO₃)₂ and changes resulting from new bond(s) formation and/or decomposition. XRD indicated that there are no peaks assigned for CuO, which weakens the composite antimicrobial activity. Optical analysis showed an increase in the band gap with copper (II) nitrate concentration over 3%. Additionally, the electrical impedance of the resulting composite increased by approximately one decade. A detailed electrical analysis of the charge-carrier types is provided. Moreover, the antimicrobial activity of chitosan is slightly enhanced by the additive copper (II) nitrate in a dose-dependent manner. The current research offers a mechanistic understanding of the structure–property relationships that govern the behavior of Cu(NO₃)₂–chitosan composites, emphasizing the significant influence of processing conditions on adapting of their dielectric and biological properties. Full article

The causative event in transmissible spongiform encephalopathies is the misfolding of the prion protein (PrP), a process influenced, in a way that is not yet fully understood, by transition metal ions, particularly copper, which modulate folding, aggregation, and redox activity. In this study, we investigated the interaction of copper(II) ions with the prion fragment PrP(95–126), which includes the non-octarepeat high-affinity sites His96 and His111, as well as an amyloidogenic tail involved in PrP misfolding and membrane interaction. UV–vis and circular dichroism analyses revealed the predominant formation of a 1:1 Cu/PrP(95–126) complex, accompanied by modest restructuring, consistent with an increased aggregation propensity upon copper binding. The Cu/PrP(95–126) complexes exhibited limited redox activity toward catechol substrates, which was further reduced in membrane-mimetic systems such as SDS micelles and large unilamellar vesicles (LUVs). His96 appears not to play a critical role in copper coordination or redox activation. This study explores the coordination modes and reactivity of copper(II) with PrP, as well as employing a membrane mimic, aspects that are still highly controversial in the literature, providing insights for further in vitro studies. Full article

Sustainable valorization of biomass through hydrothermal carbonization (HTC) represents an environmentally benign method for producing carbon materials for water treatment applications. This research aims to optimize the production of hydrochar from waste food by focusing on parameter optimization, physicochemical characterization, and the capacity of hydrochar to act as an adsorbent for the removal of the copper (II) ion from polluted water. A design of experiments using the RSM approach was employed to evaluate and optimize the influence of carbonization temperature, ranging from 180 to 250 °C, with a residence time of 2–5 h. The predictive ability of the MINITAB-generated model was close to accurate, as demonstrated by the design application for process simulation. The maximum % hydrochar yield was 72.65% for the experimental yield and 71.53% for the predicted yield, both obtained from a sample carbonized at 166 °C for 3.5 h. Batch adsorption experiments were conducted to assess the hydrochar’s ability to remove Cu²⁺ from aqueous solutions, and the Langmuir and the Freundlich isotherms were fitted at different pH levels. A comprehensive characterization of the produced hydrochar was conducted using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray fluorescence (XRF), and scanning electron microscopy (SEM-EDS). The results revealed significant modifications in surface morphology, pore development, and the presence of oxygen-containing functional groups. Based on the findings in this report, it is safe to conclude that hydrochar derived from food waste could serve as a potential adsorbent. Overall, the study demonstrates that sustainable hydrochar production from biomass can simultaneously address waste management challenges and provide an efficient solution for heavy metal removal, thereby advancing circular bioeconomy and environmental protection. Full article

In this study, we present new data about the cytotoxic activity of metal complexes of salinomycin with Co(II), Cu(II) and Zn(II) against human cervical cancer (HeLa) and melanoma (A375, SH-4) cell lines. The effect of the compounds on cell viability and proliferation was evaluated in short-term experiments (up to 72 h) with monolayer cultures using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test, neutral red uptake (NR), crystal violet staining (CV) and double staining with acridine orange (AO) and propidium iodide (PI). The cytotoxic effect of the metal complexes of salinomycin was found to be comparable and even superior to that of the commercial antitumor agents cisplatin and oxaliplatin. Long-term experiments revealed the ability of the compounds to completely suppress 3D cell growth when applied at concentrations ≥ 3.1 μM (for HeLa cells) and ≥6.2 µM (for A375 cells). Embryonic Lep-3 cells are highly sensitive to the influence of the complexes investigated, whereas non-tumor HaCaT human keratinocytes exhibit relatively higher resistance to their cytotoxic effect compared to tumor cell lines. The Zn(II) disalinomycinate exerted the highest selectivity index among the tested compounds against melanoma cells, whereas the non-coordinated antibiotic showed pronounced selectivity toward HeLa cells. Full article