Cupric Ion Research Articles

Cyanofuran-based ratiometric fluorescent probe for monitoring hypochlorite and cupric ion in cells and in vivo

Hypochlorite (ClO−) mediates various physiological processes and diseases as a reactive oxygen species. The visualization of the concentration changes of endogenous hypochlorite in cells and in vivo faces great challenges due to the single-signal (spectrum) variation. In this study, a multifunctional ratiometric fluorescent probe IBA was designed and developed for analyzing hypochlorite and Cu2+ independently through a synergetic FRET-PET mechanism. The sensor displayed excellent capacities in anti-interference capacity and sensitivity during the analysis processes of hypochlorite and Cu2+. In particular, IBA showed different fluorescence signal for hypochlorite and Cu2+ meeting the need of independent analysis. And taking advantage of excellent optical properties of the probe in detecting hypochlorite, it successfully monitored the fluctuation of exogenous and endogenous hypochlorite in A549 cells. Moreover, IBA could visualize the changes of hypochlorite in living zebrafish with the fluorescent change between red and green. Overall, the designed novel probe IBA can serve as a potential tool to analyze hypochlorite and Cu2+, and the exploration of the variations of hypochlorite through living imaging shows potential to study the relevant molecular mechanisms and metabolism routes during multifarious physiological activities.

Comparative Analysis of Antioxidant, Anticholinesterase, and Antibacterial Activity of Microbial Chondroitin Sulfate and Commercial Chondroitin Sulfate.

Chondroitin synthesis was performed using the recombinantEscherichia coli(C2987) strain created by transforming the plasmid pETM6-PACF-vgb, which carries the genes responsible for chondroitin synthesis,kfoA, kfoC, kfoF,and theVitreoscillahemoglobin gene (vgb). Then, Microbial chondroitin sulfate (MCS)'s antioxidant, anticholinesterase, and antibacterial activity were compared with commercial chondroitin sulfate (CCS). The antioxidant studies revealed that the MCS and CCS samples could be potential targets for scavenging radicals and cupric ion reduction. MCS demonstrated better antioxidant properties in the ABTS assay with the IC50 value of 0.66 mg than CCS. MCS showed 2.5-fold for DPPH and almost 5-fold for ABTS•+ (with a value of 3.85 mg/mL) better activity than the CCS. However, the compounds were not active for cholinesterase enzyme inhibitions. In the antibacterial assay, the Minimum inhibitory concentration (MIC) values of MCS againstS. aureus, E. aerogenes, E. coli, P. aeruginosa, andK. pneumoniae(0.12, 0.18, 0.12, 0.18, and 0.18 g/mL, respectively) were found to be greater than that of CCS (0.42, 0.48, 0.36, 0.36, and 0.36 g/mL, respectively). This study demonstrates that MCS is a potent pharmacological agent due to its physicochemical properties, and its usability as a therapeutic-preventive agent will shed light on future studies.

Click reaction-based single-particle dark-field microscopy: A visual platform for the highly sensitive and selective detection of pyrophosphatase

Inorganic pyrophosphatase (PPase) plays significant roles in diverse pathophysiological processes, therefore, developing a reliable method to measure PPase activity is crucial for the early diagnosis of the related diseases. In this work, a novel platform with single-particle dark-field microscopy (DFM), consisting of core gold nanoparticles (AuNPs), satellite AuNPs, pyrophosphate ions (PPi), copper ions (Cu2+), and sodium ascorbate (NaAsc), is designed for the selective and sensitive analysis of PPase according to a click reaction. After the introduction of PPase, the coordination between PPi and Cu2+ can be destroyed by catalyzing the hydrolysis of PPi to release free Cu2+ which can be reduced by NaAsc to produce cuprous ions (Cu+). Then the formed Cu+ promotes the click reaction between azide-modified core AuNPs and alkynyl-modified satellite AuNPs to cause the significant redshift of the localized surface plasmon resonance (LSPR) spectra of core AuNPs. Thus, PPase can be ultra-sensitively detected with a low detection limit of 0.003 U/L in a wide linear range from 0.01 to 1 U/L. This click reaction-based DFM technique can also be used to assess PPase inhibition, which suggests that it has a lot of potential for both the screening of PPase inhibitors and the diagnosis of PPase-related disorders.

Indole‐3‐carbinol (I3C): Inhibition Effect on Monoamine Oxidase A (MAO‐A), Monoamine Oxidase B (MAO‐B) and Cholinesterase Enzymes, Antioxidant Capacity and Molecular Docking Study

AbstractMonoamine oxidase A and B (MAO‐A and MAO‐B) isoenzymes play key roles in neurodegenerative diseases like Parkinson's disease (PD) and Alzheimer's disease (AD), arising from dopamine metabolism defects. Acetylcholinesterase (AChE) catalyzes acetylcholine (ACh) metabolism, linked to AD. This study investigated indole‐3‐carbinol (I3C) for in vitro inhibition on AChE, BChE, MAO‐A, and MAO‐B. In inhibition studies, I3C showed potent inhibitory potential against AChE and BChE enzymes (IC50 values of 239.29 μM and 21.51 μM, respectively). Corresponding Ki values were 243.52 μM for AChE and 2.78 μM for BChE, indicating significant inhibitory activity. Additionally, I3C effectively inhibited MAO‐A and MAO‐B enzymes (IC50 values of 19.52 μM and 40.05 μM, respectively). Its antioxidant and radical scavenging capabilities were assessed using various methods, including Fe3+‐Fe2+ reducing capacity, cupric ion (Cu2+) reduction by Cuprac method, reducing capacity by FRAP method, 1,1‐diphenyl‐2‐picryl‐hydrazyl free radical (DPPH⋅) scavenging method, and 2,2'‐azino‐bis(3‐ethylbenzthiazoline‐6‐sulfonic acid) radical (ABTS⋅+) scavenging. I3C showed potent inhibitory effects on AChE, BChE, MAO‐A, and MAO‐B enzymes. Additionally, I3C displayed a strong antioxidant capacity, suggesting its therapeutic potential as an antioxidant agent. Molecular docking simulations provided insights into I3C′s interactions with the target enzymes, informing the design of novel therapeutic agents for neurodegenerative diseases.

In-vitro anti-diabetic, anti-Alzheimer, anti-tyrosinase, antioxidant activities of selected coumarin and dihydroisocoumarin derivatives

Benzo-α-pyrone structured coumarin derivatives are secondary metabolites first obtained from Coumarouna odorata in 1822. Coumarin and its structural isomer dihydroisocoumarin derivatives are found in many different sources in nature. Several different bioactivities of these compounds have been reported. In this study, preliminary activity screening and comparison of four purchased coumarin derivatives (esculetin, esculin monohydrate, umbelliferon, scoparone) and four previously isolated 3-phenyl-3,4-dihydroisocoumarin derivatives (thunberginol C, scorzocreticoside I, scorzocreticoside II, scorzopygmaecoside) from a medicinal plant were carried out by in-vitro methods. α-Glucosidase, acetylcholinesterase, butyrylcholinesterase, tyrosinase inhibitor activities and antioxidant potentials of the compounds were evaluated. Consequently, thunberginol C (free – not glycosylated form of 3,4-dihydroisocoumarin structure) showed better potential in all enzyme inhibitory activities compared to coumarin structure. Particularly, α-glucosidase inhibitory activity of this compound with a very low IC50 value (94.76±2.98 µM) compared to standard acarbose (1036.2±2.70 µM) should be noted. Glycosylation and/or methoxy substitution of 3,4-dihydroisocoumarin structure resulted a significant decrease in all tested enzyme inhibitory activities. The structures of esculin MH, umbelliferone, scoparone, scorzocreticoside I, and scorzopygmaeceoside might be considered in further synthetic studies as selective acetylcholinesterase inhibitors. Thunberginol C has a promising potential in tyrosinase inhibitory activity. Esculetin and thunberginol C showed the best results with high potentials in antioxidant activity via 2,2-diphenyl-1-picryl-hydrazyl-hydrate free radical scavenging, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid cation radical decolorization, and cupric ion reducing antioxidant capacity assays compared to the standards.

Potential antioxidant, anticholinergic, antidiabetic and antiglaucoma activities and molecular docking of spiraeoside as a secondary metabolite of onion (Allium cepa)

Onion contains many dietary and bioactive components including phenolics and flavonoids. Spiraeoside (quercetin-4-O-β-D-glucoside) is one of the most putative flavonoids in onion. Several antioxidant techniques were used in this investigation to assess the antioxidant capabilities of spiraeoside, including 1,1-diphenyl-2-picrylhydrazyl radical (DPPH·) scavenging, N,N-dimethyl-p-phenylenediamine radical (DMPD•+) scavenging, 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulphonate) radical (ABTS•+) scavenging activities, cupric ions (Cu2+) reducing and potassium ferric cyanide reduction abilities. In contrast, the water-soluble α-tocopherol analogue trolox and the conventional antioxidants butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA), and α-tocopherol were utilized as the standards for evaluation. Spiraeoside scavenged the DPPH radicals an IC50 of 28.51 μg/mL (r2: 0.9705) meanwhile BHA, BHT, trolox, and α-tocopherol displayed IC50 of 10.10 μg/mL (r2: 0.9015), 25.95 μg/mL (r2: 0.9221), 7.059 μg/mL (r2: 0.9614) and 11.31 μg/mL (r2: 0.9642), accordingly. The results exhibited that spiraeoside had effects similar to BHT, but less potent than α-tocopherol, trolox and BHA. Also, inhibitory effects of spiraeoside were evaluated toward some metabolic enzymes including acetylcholinesterase (AChE), butyrylcholinesterase (BChE), carbonic anhydrase II (CA II) and α-glycosidase, which are related to a number of illnesses, such as Alzheimer’s disease (AD), diabetes mellitus and glaucoma disorder. Spiraeoside exhibited IC50 values of 4.44 nM (r2: 0.9610), 7.88 nM (r2: 0.9784), 19.42 nM (r2: 0.9673) and 29.17 mM (r2: 0.9209), respectively against these enzymes. Enzyme inhibition abilities were compared to clinical used inhibitors including acetazolamide (for CA II), tacrine (for AChE and BChE) and acarbose (for α-glycosidase). Spiraeoside demonstrated effective antioxidant, anticholinergic, antidiabetic and antiglaucoma activities. With these properties, it has shown that Spiraeoside has the potential to be a medicine for some metabolic diseases.

Molecular features, antioxidant potential, and immunological expression assessment of thioredoxin-like protein 1 (TXNL1) in yellowtail clownfish (Amphiprion clarkii)

Thioredoxin-like protein 1 (TXNL1) is a redox-active protein belonging to the thioredoxin family, which mainly controls the redox status of cells. The TXNL1 gene from Amphiprion clarkii (AcTXNL1) was obtained from a pre-established transcriptome database. The AcTXNL1 is encoded with 289 amino acids and is predominantly localized in the cytoplasm and nucleus. The TXN domain of AcTXNL1 comprises a34CGPC37 motif with redox-reactive thiol (SH-) groups. The spatial distribution pattern of AcTXNL1 mRNA was examined in different tissues, and the muscle was identified as the highest expressed tissue. AcTXNL1 mRNA levels in the blood and gills were significantly increased in response to different immunostimulants. In vitro antioxidant capacity of the recombinant AcTXNL1 protein (rACTXNL1) was evaluated using the ABTS free radical-scavenging activity assay, cupric ion reducing antioxidant capacity assay, turbidimetric disulfide reduction assay, and DNA nicking protection assay. The potent antioxidant activity of rAcTXNL1 exhibited a concentration-dependent manner in all assays. Furthermore, in the cellular environment, overexpression of AcTXNL1 increased cell viability under H2O2 stress and reduced nitric oxide (NO) production induced by lipopolysaccharides (LPS). Collectively, the experimental results revealed that AcTXNL1 is an antioxidant and immunologically important gene in A. clarkii.

Modeling of Sensory Properties of Poppy Sherbet by Turkish Consumers and Changes in Quality Properties during Storage Process.

Poppy is an important edible plant containing bioactive components. This study aimed to produce good-tasting poppy sherbet by determining the content using a response surface methodology (RSM). At the same time, bioactive components, phenolic compounds, and color properties were investigated in optimum poppy sherbet during storage; 0.26 g of dried corn poppy flowers, 0.15 g of citric acid, and 4.29 g of sucrose values were the most promising, achieving high scores for color, smell, taste, and general acceptance from sensory properties (sensory score of 8.55 for color; 7.19 for smell; 8.38 for taste; 7.98 for general acceptability). A total of nine polyphenols were detected in the optimum poppy sherbet sample; gallic acid was the most common. There was no statistically significant difference between the samples stored on the 0th and 30th days regarding gallic acid content (23.886 ± 0.164 μg/mL, 23.403 ± 0.343 μg/mL) and protocatechuic acid (1.146 ± 0.048 μg/mL, 1.047 ± 0.038 μg/mL). Total flavonoid contents (TFC), total phenolic contents (TPC), CUPRAC (cupric ion reducing antioxidant capacity), DPPH (e free radical diphenylpicrylhydrazyl), total monomeric anthocyanin (TAC), and color values were found to decrease as the storage period increased. It was considered that a highly palatable and rich bioactive component product could be obtained.

Copper–zinc/chitosan complex hydrogels: Rheological, degradation and biological properties

Polymer hydrogels crosslinked by therapeutic metal ions have attracted increased interest in recent years due to their unique and versatile properties. Chitosan hydrogels are widely investigated for various biomedical applications such as tissue engineering and drug delivery. Copper and zinc ions are considered as therapeutic metal ions, that have important roles in bone regeneration. The aim of this study was to investigate the physicochemical and biological properties of bimetallic–chitosan complex hydrogels with different cupric and zinc ions content. Scanning electron microscopy (SEM) revealed changes in the morphology from the microstructure with larger, tubular pores for aerogels with higher Zn content, to the sheets-like structure with long pores for samples with higher Cu content. FTIR analysis indicated the formation of bimetallic–chitosan aerogels. The obtained X-ray diffraction patterns showed a broadening of chitosan's characteristic diffraction maximum, while characterization of physical properties showed decreased swelling ability and increased shear modulus with higher Cu content. ICP-MS results showed a negligible amount of copper and zinc ions released under physiological conditions during 24 h indicating a strong physical crosslink between metal ions and chitosan chains. Furthermore, accelerated in vitro degradation showed that hydrogels maintained good stability during four weeks of lysozyme activity. The MTT assay indicated that the cytotoxicity of Cu2+–Zn2+/chitosan complexes could be adjusted by the amount of cupric ions. All results imply that Cu2+ and Zn2+ ions act as physical crosslinkers of the polymer network. Also, results are in agreement with the prediction of density functional theory (DFT) which indicated stronger chitosan–Cu tetrahedral aqua complex interactions in comparison to the chitosan–[Zn(H2O)4]2+ interactions.

The Effects of Chloride on the High-Temperature Pressure Oxidation of Chalcopyrite: Some Insights from Batch Tests—Part 1: Leach Chemistry

The complete reaction of chalcopyrite at ≥220 °C under pressure oxidation conditions (10 or 20% w/w pulp density, PO2 700 kPa) is a clean, near complete process, yielding high copper extractions (~99%) in an acidic leach liquor composed of dissolved metal sulphates, when high-quality process water is employed. However, when the process water contains chloride ions, here 3–100 g/L, although the copper extraction rate is enhanced, complete oxidation of sulphur under batch processing conditions is delayed. Chloride addition, therefore, appears to favour an oxidation mechanism that liberates cupric ions and preferentially forms elemental sulphur over sulphate. This provides evidence for the decoupling of the copper extraction and sulphate formation reactions. Increasing the reaction temperature, here to 245 °C, increases the rate of sulphuric acid formation and decreases the iron concentration in the leach liquor. The study also examines the effects of various upfront acid and other salt additions upon copper extraction. Added sulphuric acid was shown to slow the reaction, whereas salts such a cupric chloride and sodium sulphate had small effects on the rate and extent of copper extraction.

Recovery of nickel from spent multilayer ceramic capacitors: A novel and sustainable route based on sequential hydrometallurgical and photocatalytic stages

The depletion of primary metal sources and the extensive use of nickel necessitate its extraction from secondary resources. In this study, we employed a chloride-based solution containing cupric ions (NaCl/CuCl2) to enable a straightforward recovery process for nickel from Ni-containing waste materials. Prior to application in real systems, we evaluated different operating conditions using metallic nickel particles, including chloride and cupric ion concentrations, system temperature, and pH. Optimal efficiency was achieved at T = 60 °C, pH = 5.0, [Cu(II)]0 = 5.0 × 10−3 M, and [Cl]0 = 6.0 M, resulting in complete dissolution of metallic Ni (58 ppm) within 180 min. This optimized leaching system was then applied to exhausted nickel-containing multilayer ceramic capacitors (MLCCs) matrixes, leading to 80% Ni recovery. FESEM-EDX and XRD analysis characterized both synthetic and real matrixes. Additionally, we proposed a viable route for selective metal recovery through precipitation and photodeposition on titanium dioxide. Complete copper photodeposition occurred after 150 min, while Ni precipitation as Ni(OH)2 was achieved by adjusting the solution pH to 10. Experimental data from runs with the synthetic matrix were analyzed using a shrinking spherical particle model.

Efficient removal of sulfamethoxazole by biomass phosphorus-derived Cu3P/biochar catalyst combined with persulfate

Sulfamethoxazole (SMX) is ubiquitous in environments with concentrations ranging from nano-gram per liter to milli-gram per liter in practice, especially in water matrices (surface water and wastewater), posing a grave threat to ecosystems for its antibacterial and persistent characteristics. Efficient SMX removal is critical for water purification. Herein, the nano and micron Cu3P particles are synthesized on biochar utilizing phytic acid (PA) doped rice brans. PA facilitates the transformation of Cu-containing precursors to Cu3P on biochar, promoting catalytic performance. Under the conditions of 0.15 g/L catalyst (6PA-Cu11), 3.0 mM persulfate (PS), and pH 7.00, sulfamethoxazole (SMX) at a concentration of 0.25, 0.50, 1.00, and 10.00 mg/L can be completely removed within 30, 60, and 180 min, respectively. Moreover, the combination of Cu3P/biochar and persulfate exhibits preferable catalytic performances for SMX removal in sodium humate solution and surface water matrices, demonstrating the broad applicability of such a catalytic system for water purification. Sulfate radical (SO4−•) and hydroxy radical (•OH) play vital roles in the oxidation of SMX, with 1O2 assisting in. Except for cuprous ion (≡Cu+), partially charged copper ions (≡Cuδ+) and phosphorus ions (≡Pγ−) in Cu3P, owning the electron-donating ability, are found to participate in the activation of PS or the reduction of high-valent copper ions depending on density functional theory (DFT) calculations. Biochar carrier enhances the catalytic role of copper ions in Cu3P and facilitates the recovery of active sites by improving the desorption of the activation product (SO42−) from the Cu3P surface. This research promotes the practicability of the Cu3P/biochar catalyst in the advanced oxidation process for refractory organic pollutant removal and deepens the perception of its catalytic mechanisms.

Antioxidant, α-amylase and α-glucosidase Inhibitory Activities of Aqueous and Methanolic Extracts From Athamanta sicula L.

Introduction: Oxidative stress plays a major role in developing diabetes complications; therefore, it is possible to use natural antioxidants as therapeutic agents for diabetes. Aims: This study aimed to find an important source of phenolics from Athamanta sicula L. (A. sicula) and confirm that this plant could be a significant source of medically important natural compounds by confirming its antioxidant, α-amylase and α-glucosidase inhibitory potential. Methods: Antioxidant property was performed using 2,2′-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, metal chelating, and cupric reducing antioxidant capacity methods. The α-amylase and α- glucosidase inhibitory activities were investigated using an in vitro model. Moreover, polyphenols and flavonoid contents of the tested extracts were carried out. Results: The methanolic extract exhibited the highest phenolic and flavonoid content compared to the aqueous extract. However, aqueous extract possessed the strongest antioxidant activity (DPPH scavenging, metal chelating, and Cupric ion reducing antioxidant capacities), α-amylase and α-glucosidase inhibitory effects. No correlation between phenolic content and antioxidant and enzyme inhibitory activities of A. sicula L. extracts was observed. Conclusion: The results showed that this plant could be a significant source of medically important natural compounds.

Chemical Composition and In Vitro Antimicrobial, Antioxidant, and Tyrosinase-Inhibiting Activity of Essential Oils Extracted From the Leaves and Twigs of Calocedrus macrolepis var. formosana

In this study, we focused on evaluating the antimicrobial, antioxidant, and tyrosinase-inhibiting properties of leaf and twig essential oils from Calocedrus macrolepis var. formosana. Additionally, we determined the major components associated with these effects. The findings revealed that α-pinene (36.4%) and limonene (23.6%) were the dominant components in the leaf essential oil, while α-pinene (36.2%), ferruginol (22.5%), and limonene (13.1%) were the major constituents in the twig essential oil. However, when comparing the biological activities of the 2 essential oils, the twig essential oil demonstrated excellent inhibitory effects against skin pathogens, as well as strong antioxidant and tyrosinase-inhibiting activities, in contrast to the leaf essential oil. The twig essential oil also exhibited excellent antimicrobial activity against 5 skin pathogenic strains, with the strongest inhibitory effect being that against Staphylococcus aureus, S epidermidis, and Candida albicans, which was accompanied by an inhibition zone of 46 to 48 mm, a minimum inhibitory concentration (MIC) of 125 μg/mL, and a minimum bactericidal concentration (MBC) of 250 μg/mL. The inhibitory activity of the twig essential oil against lipid peroxidation was found to be potent, as evidenced by an IC50 value of 216 ± 1.9 μg/mL. It also exhibited strong scavenging activity against free radicals, including 2,2-diphenyl-1-picrylhydrazyl (DPPH) (IC50 = 121.6 ± 0.5 μg/mL) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) (IC50 = 136.8 ± 1.6 μg/mL) cation radicals. In addition, it exhibited a high cupric ion reducing–antioxidant capacity (CUPRAC), with the A0.50 value determined to be 186.28 ± 0.5 μg/mL. It also exhibited adequate activity in terms of inhibiting in vitro tyrosinase activity, as evidenced by an IC50 value of 168.5 ± 0.6 μg/mL. Further analysis revealed that ferruginol was the active component responsible for the antimicrobial, antioxidative, and tyrosinase-inhibiting activities observed in twig oil. These findings suggest that the twig oil is a promising candidate for further research because of its favorable antimicrobial, antioxidative, and tyrosinase-inhibiting activity.

Copper Nanoparticles Supported on ZIF-8: Comparison of Cu(II) Reduction Processes and Application as Benzyl Alcohol Oxidation Catalysts.

We report the synthesis of a stable heterogeneous catalyst based on copper metal nanoparticles with oxidized surface supported on ZIF-8 for the oxidation of benzyl alcohol under mild temperature and using air as a sustainable oxygen source as well as for the implementation of the tandem "one-pot" catalytic system allowing the sustainable synthesis of benzylidene malononitrile. The influence of the reduction process applied to form the nanoparticle upon the catalyst texture and its performances was extensively examined. After ZIF-8 impregnation with a copper chloride precursor, the reduction of cupric ions into Cu0 nanoparticles was carried out according to two procedures: (i) by soaking the solid into a solution of NaBH4 and (ii) by submitting it to a flow of gaseous H2 at 340 °C. The in-depth physicochemical characterization and comparison of the resulting two types of Cu/ZIF-8 materials reveal significant differences: the reduction with NaBH4 led to the formation of 16 nm sized Cu0 nanoparticles (NP) mainly localized on the external surface of the ZIF-8 crystals together with ZnO nanocrystallites, while the reduction under H2 flow resulted in Cu0 nanoparticles with a mean size of 22 nm embedded within the bulk of ZIF-8 crystals. More, when NaBH4 was used to reduce cupric ions, ZnO particles were highlighted by high-resolution microcospy imaging. Formation of ZnO impurities was confirmed by the photoluminescence analysis of ZIF-8 after NaBH4 treatment. In contrast, ZnO was not detected on ZIF-8 treated with H2. Both types of Cu0 NPs supported on ZIF-8 were found to be active as catalysts toward the aerobic oxidation of benzyl alcohol under moderate temperature (T < 80 °C) and using air as a sustainable O2 source. Benzaldehyde yield of 66% and selectivity superior to 90% were obtained with the Cu/ZIF-8 catalyst prepared under H2 flow after 24 h under these conditions. The same material could be recycled 5 times without loss of activity, unlike the catalysts synthesized with NaBH4, as a result of the leaching of the surface copper NPs over the consecutive catalytic cycles. Finally, the most stable catalyst was successfully implemented in a tandem "one-pot" catalytic system associating benzyl alcohol oxidation and Knoevenagel condensation to synthesize benzylidene malononitrile.

A Pretreatment of Refractory Gold Ores Containing Sulfide Minerals to Improve Gold Leaching by Ammonium Thiosulfate: A Model Experiment Using Gold Powder and Arsenic-Bearing Sulfide Minerals

The use of thiosulfate to extract gold from refractory ores is promising because of its non-toxicity and high selectivity. Sulfide minerals (i.e., pyrite, arsenopyrite, chalcopyrite), major gold carriers in refractory gold ores, however, hinder gold extraction due to the high consumption of a lixiviant. In this study, a new method to improve gold extraction from sulfide bearing gold ores is proposed based on the model experiments using a mixture of gold powder and arsenopyrite-bearing sulfide (HAsBS) ore. The effects of HAsBS ore on gold leaching in ammonium thiosulfate solutions were investigated, and it was found that gold extraction in the presence of HAsBS ore was suppressed because of the unwanted decomposition of thiosulfate on the surface of sulfide minerals. To improve gold extraction in the presence of the sulfide minerals, this study investigated the effects of the pretreatment of HAsBS ore using ammonium solutions containing cupric ions and confirmed that HAsBS ore was oxidized in the pretreatment and its surface was covered by the oxidation products. As a result, thiosulfate consumption was minimized in the subsequent gold leaching step using ammonium thiosulfate, resulting in an improvement in gold extraction from 10% to 79%.

The accelerated recovery of silver using the nitrite-copper novel system: Development of the kinetic model

This research presents a systematic-kinetic analysis of silver leaching from pure metallic silver using the NO2-Cu2+ novel system, with the aim to maximize the silver recovery and decrease the massive consumption of reagents. The effect of pH, nitrite ions concentration, cupric ions concentration, temperature and stirring rate on silver leaching kinetics and recovery was evaluated. The thermodynamic and leaching results showed that a decrease of pH from 5.4 to 4.5 increases remarkably the silver leaching kinetics, while the parasite precipitation of copper hydroxysulfate species is inhibited. The silver leaching kinetics is also favored when nitrite and copper concentrations are increased up to 1.5 and 0.2 M, respectively. The fundamental kinetic analysis revealed that silver leaching mechanism from its metallic form with this system was incomplete and follows the next kinetic model: t = [ 10-0.52pH [NO2–]1.2 [Cu2+]0.522.63 × 109e-56,900/RT][ 1–3(1-x)2/3 + 2(1-x)], where the diffusion of fluid species through a non-conventional ash layer is the rate determining step of the leaching process. Finally, the dissolved silver can be easily recovered in its metallic form (high purity > 99%) using a simple cementation step, which permits the recycling of the leaching solution.

In-situ growth of porous rod-like tungsten oxide for electrochemical determination of cupric ion

Preconcentration can effectively enhance the detection performance of electrodes in the electrochemical detection of heavy metal ions, but it also presents challenges for real-time monitoring. Several attempts have been made to optimize preconcentration by improving the adsorption capacity or detection mechanism of the electrode. The valence transfer of tungsten oxide between W5+/W6+ can participate in the reduction between the electrode material and heavy metal ions, playing a role in preconcentration to some extent. Therefore, we developed a WO3/SSM electrochemical sensor for the detection of Cu(II) that utilizes the valence variation property of WO3. The crystallinity and microstructure of the WO3/SSM electrode can be regulated by controlling the deposition parameters, and we prepared three types of WO3/SSM with different morphologies to identify the influence of the electrochemical effective surface area. The proposed electrode shows high performance as a Cu(II) sensor under short preconcentration time (60 s), with an excellent sensitivity of 14.113 μA μM−1 cm−2 for 0.1–10.0 μM and 4.7356 μA μM−1 cm−2 for 10.0–20.0 μM. Overall, the combined effect of morphology and valence transfers shortens the preconcentration time and optimizes preconcentration while ensuring excellent electrode performance. This WO3/SSM electrode is expected to drive great advances in the application of tungsten oxide in the electrochemical detection of heavy metal ions.

Selective Cementation of Gold Using an Iron Oxide and Zero-Valent Aluminum Galvanic System from Gold–Copper Ammoniacal Thiosulfate Solutions

Ammonium thiosulfate leaching is a promising alternative to the conventional cyanide method for extracting gold from ores. However, strategies for recovering gold from the leachate are less commercially used due to its low affinity to gold. The present study investigated the recovery of gold from the leachate using iron oxides (hematite, Fe2O3 or magnetite, Fe3O4). Cementation experiments were conducted by mixing 0.15 g of aluminum powder as an electron donor and 0.15 g of an electron mediator (activated carbon, hematite, or magnetite) in 10 mL of ammonium thiosulfate leachate containing 100 mg/L gold ions and 10 mM cupric ions for 24 h at 25 °C. The results of the solution analysis showed that when activated carbon (AC) was used, the gold was recovered together with copper (recoveries were 99.99% for gold and copper). However, selective gold recovery was observed when iron oxides were used, where the gold and copper recoveries were 89.7% and 21% for hematite and 85.9% and 15.4% for magnetite, respectively. An electrochemical experiment was also conducted to determine the galvanic interaction between the electron donor and electron mediator in a conventional electrochemical setup (hematite/magnetite–Al as the working electrode, Pt as the counter electrode, Ag/AgCl as the reference electrode) in a gold–thiosulfate medium. Cyclic voltammetry showed a gold reduction “shoulder-like” peak at −1.0 V using hematite/Al and magnetite/Al electrodes. Chronoamperometry was conducted and operated at a constant voltage (−1.0 V) determined during cyclic voltammetry and further analyzed using SEM-EDX. The results of the SEM-EDX analysis for the cementation products and electrochemical experiments confirmed that the gold was selectively deposited on the iron oxide surface as an electron mediator.

Monofloral Corn Poppy Bee-Collected Pollen-A Detailed Insight into Its Phytochemical Composition and Antioxidant Properties.

The aim of this study was to compile a detailed phytochemical profile and assess the antioxidant properties of bee-collected pollen (PBP) obtained from corn poppy (Papaver rhoeas L.) plants. To achieve this, a lipid fraction was prepared for quantifying fatty acids using GC-FID. Extractable and alkaline-hydrolysable PBP fractions (obtained from a defatted sample) were used to determine the qualitative and quantitative profiles of phenolic compounds, phenylamides and alkaloids using UHPLC/Q-ToF-MS. Additionally, various spectrophotometric assays (TAC, FRP, CUPRAC, DPPH⦁) were conducted to evaluate the antioxidant properties. Phenolic compounds were more present in the extractable fraction than in the alkaline-hydrolysable fraction. Luteolin was the predominant compound in the extractable fraction, followed by tricetin and various derivatives of kaempferol. This study presents one of the first reports on the quantification of tricetin aglycone outside the Myrtaceae plant family. The alkaline-hydrolysable fraction exhibited a different phenolic profile, with a significantly lower amount of phenolics. Kaempferol/derivatives, specific compounds like ferulic and 5-carboxyvanillic acids, and (epi)catechin 3-O-gallate were the predominant compounds in this fraction. Regarding phenylamides, the extractable fraction demonstrated a diverse range of these bioactive compounds, with a notable abundance of different spermine derivatives. In contrast, the hydrolysable fraction contained six spermine derivatives and one spermidine derivative. The examined fractions also revealed the presence of seventeen different alkaloids, belonging to the benzylisoquinoline, berberine and isoquinoline classes. The fatty-acid profile confirmed the prevalence of unsaturated fatty acids. Furthermore, both fractions exhibited significant antioxidant activity, with the extractable fraction showing particularly high activity. Among the assays conducted, the CUPRAC assay highlighted the exceptional ability of PBP's bioactive compounds to reduce cupric ions.