Metal Chelating Research Articles

Synthesis of Spherical Mn2O3 Nanozymes from Different Green Precursors for their Innovative Applications in Catalytic Properties and Bioactivity.

Here, spherical Mn2O3 nanozymes were synthesized via a one-step green method using different green precursors, and their physicochemical properties and biological activities were monitored with various green precursors. Powder X-ray diffraction (PXRD) was performed to determine the crystalline properties and phases involved in the formation of cubic Mn2O3 nanozymes. The synthesized nanozymes were spherical and examined by SEM and FESEM studies. All of the samples synthesized using different green precursors exhibited different sizes but similar spherical shapes. Moreover, all green-synthesized nanozymes catalyzed the oxidation reaction of the chromogenic substrate 3,3'5,5' tetramethylbenzidine (TMB) in the absence of H2O2, and A2 (lemon-mediated Mn2O3 nanozymes), which the followed Michaelis-Menten kinetics, showed the best activity. Therefore, A2 (lemon-mediated nanozyme) showed oxidase-mimicking activity with distinct Km and Vmax values calculated by the Lineweaver-Burk plot. Furthermore, the current nanozymes demonstrated a significant ability to kill both Gram-negative and Gram-positive bacteria as well as effectively destroy biofilms under physiological conditions. Moreover, the green-mediated nanozymes also displayed ROS-scavenging activity. Our nanozymes exhibited scavenging activity toward OH and O2-• radicals and metal chelation activity, which were investigated colorimetrically. Therefore, these nanozymes might be used as effective antibacterial agents and also for the consumption of reactive oxygen species.

Process optimization and identification of antioxidant peptides from enzymatic hydrolysate of bovine bone extract, a potential source in cultured meat

Bone protein is a significant secondary product of the meat industry, comprising a substantial quantity of protein. These proteins could be broken down through enzymatic hydrolysis to generate antioxidant peptides. This study aimed to produce antioxidant peptides from bovine bone extract by enzymatic hydrolysis utilizing Flavourzyme and Protamex by optimizing enzyme amounts and time using the Box–Behnken design. The final optimized conditions obtained through the model were as follows: The amount of Flavourzyme was 1,100 U, the amount of Protamex was 2,814 U, and the time was 3.77 (h). Bovine bone extract hydrolysate (BBEH) was purified stepwise using ultrafiltration membranes with molecular cutoffs of 5, 3, and 1 kDa. To assess the antioxidant capacity of the fractions, several methods were used, including radical scavenging activity “1,1-diphenyl-2-picrylhydrazyl (DPPH),” “2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS),” metal chelating activity (MCA), reducing power (RP), and thiobarbituric acid assay (TBA). The results indicated that the ultrafiltration fraction with a molecular weight of less than 1 kDa showed significant antioxidant activity, with 48, 42, and 50% inhibition rates for DPPH, ABTS, and metal chelating, respectively. Using size exclusion chromatography, the fraction with a molecular weight less than 1 kDa was further separated into five sub-fractions: Frac-I, Frac-II, Frac-III, Frac-IV, and Frac-V. Sub-Frac-III, which exhibits significant DPPH radical scavenging activity (55%) and a reducing power of 0.8 at 700 nm, was separated into six sub-sub-fractions using reversed-phase HPLC (RP-HPLC) based on molecular weight and hydrophobicity. The sub-sub-fraction with the highest value for DPPH radical scavenging activity was sub-Fra-III-6, which exhibited approximately 69.45% activity. The sub-Fra-III-6 was analyzed using LC–MS/MS, which identified two specific peptides: Ala-Pro-Phe with a mass of 333.12 Da and Asp-His-Val with a mass of 369.14 Da. These two peptides are likely the primary peptides that might have a crucial role in antioxidant capacity. It can be concluded that BBEH is a valuable source of natural antioxidants and has the potential to serve as a viable resource in the cultured meat industry.

Biosynthesis of novel desferrioxamine derivatives requires unprecedented crosstalk between separate NRPS-independent siderophore pathways.

Iron is essential to many biological processes but its poor solubility in aerobic environments restricts its bioavailability. To overcome this limitation, bacteria have evolved a variety of strategies, including the production and secretion of iron-chelating siderophores. Here, we describe the discovery of four series of siderophores from Streptomyces ambofaciens ATCC23877, three of which are unprecedented. MS/MS-based molecular networking revealed that one of these series corresponds to acylated desferrioxamines (acyl-DFOs) recently identified from S. coelicolor. The remaining sets include tetra- and penta-hydroxamate acyl-DFO derivatives, all of which incorporate a previously undescribed building block. Stable isotope labeling and gene deletion experiments provide evidence that biosynthesis of the acyl-DFO congeners requires unprecedented crosstalk between two separate non-ribosomal peptide synthetase (NRPS)-independent siderophore (NIS) pathways in the producing organism. Although the biological role(s) of these new derivatives remain to be elucidated, they may confer advantages in terms of metal chelation in the competitive soil environment due to the additional bidentate hydroxamic functional groups. The metabolites may also find application in various fields including biotechnology, bioremediation, and immuno-PET imaging.IMPORTANCEIron-chelating siderophores play important roles for their bacterial producers in the environment, but they have also found application in human medicine both in iron chelation therapy to prevent iron overload and in diagnostic imaging, as well as in biotechnology, including as agents for biocontrol of pathogens and bioremediation. In this study, we report the discovery of three novel series of related siderophores, whose biosynthesis depends on the interplay between two NRPS-independent (NIS) pathways in the producing organism S. ambofaciens-the first example to our knowledge of such functional cross-talk. We further reveal that two of these series correspond to acyl-desferrioxamines which incorporate four or five hydroxamate units. Although the biological importance of these novel derivatives is unknown, the increased chelating capacity of these metabolites may find utility in diagnostic imaging (for instance, 89Zr-based immuno-PET imaging) and other applications of metal chelators.

Fabrication of Cholesterol‐Imprinted Microspheres‐Based Metal‐Chelating Monomer for Cholesterol Recognition from Serum

AbstractCholesterol is an essential lipid molecule associated with various physiological and pathological processes in the human body. Elevated cholesterol levels are correlated with several diseases, such as atherosclerosis, making cholesterol a critical biomarker for health monitoring. Molecular imprinting technology was selected to fabricate cholesterol imprinted microsphere (CHOL‐IP). This approach creates tailor‐made binding sites within polymer matrices for capturing cholesterol. However, the limited functional group in steroid derivative pose a challenge for the imprinting strategy. In this study, we successfully synthesized CHOL‐IP using a metal chelating monomer, N,N′‐vinylbenzyl iminodiacetic acid (VBIDA), in conjunction with copper (II) ions. The metal coordination approach facilitated strong binding forces, resulting in improved stability and specificity of the molecularly imprinted polymer (MIP). The synthesized CHOL‐IP was tested with pooled human serum samples containing cholesterol, HDL, and LDL. The CHOL‐IP exhibited significantly higher binding efficiency towards these compounds compared to the control polymer (CP). The application of a metal‐chelating functional monomer in the synthesized CHOL‐IP revealed the potential for enhancing its strong binding property toward cholesterol. This suggests that CHOL‐IP could be employed in the development of a cholesterol‐imprinted biosensor, providing an alternative tool for cholesterol analysis in medical detection applications.

UHPLC-ESI-QTOF-MS metabolite profiles of different extracts from Pelargonium endlicherianum parts and their biological properties based on network pharmacological approaches.

In the present study, we aimed to investigate the chemical profiles and biological activities of different extracts (ethyl acetate, dichloromethane, ethanol, and water) of Pelargonium endlicherianum parts (aerial parts and roots). Free radical scavenging, reducing power, phosphomolybdenum, and metal chelating were assayed for antioxidant properties. To detect enzyme inhibitory properties, cholinesterase, amylase, glucosidase, and tyrosinase were chosen as target enzymes. The ethanol extract of the aerial parts contained higher amounts of total bioactive compounds (120.53 mg GAE/g-24.46 mg RE/g). The ethanol and water extracts of these parts were tentatively characterized by UHPLC-ESI-QTOF-MS and 95 compounds were annotated. In addition, the highest acetylcholiesterase (3.74 mg GALAE/g) and butyrylcholinesterase (3.92 mg GALAE/g) abilities were observed by the ethanol extract of roots. The water extract from aerial parts exhibited the most pronounced inhibitory effects on multiple cancer cell lines, especially A549 (IC50: 23.2 µg/mL) and HT-29 (IC50: 27.43 µg/mL) cells. Using network pharmacology, P. endlicherianum compounds were studied against cancer, revealing well-connected targets such as epidermal growth factor receptor (EGFR), phosphoinositide-3-kinase (PI3K), AKT, receptor tyrosine-protein kinase erbB-2, and growth factor receptor bound protein 2 (GRB2) with significant impact on cancer-related pathways. The results could open a new path from natural treasure to functional applications with P. endlicherianum and highlight a new study on other uninvestigated Pelargonium species.

Preparation, characterization, and computational study on transition metal complexes derived from thiophene Schiff base and evaluation of their cytotoxicity against hepatic cell line, antioxidant activities, and ligand's anticorrosive properties

Novel thiophene Schiff base ligand (L) was synthesized through the condensation of 2‐thiophene‐methylamine and 3‐formyl‐4‐methoxyphenylboronic acid. Transition metal complexes with the formulae [M(L)(H2O)2Cl]Cl2.xH2O (M = Er(III), x = 4 and La(III), x = 5) and [M(L)(H2O)Cl2]Cl.xH2O (M = Yb(III), x = 4 and Ru(III), x = 0) were synthesized. Different spectral and physicochemical methods were used to confirm and identify the stoichiometry, structure, and bonding style of transition metal chelates. The creation of 1:1 molar ratio (M:L) complexes was supported by elemental data. According to IR spectra, the thiophene Schiff base ligand (L) acted as a tridentate ligand that is neutrally coordinated by S‐thiophene, N‐azomethine, and o‐methoxy groups. All chelates formed in octahedral structures according to the findings data. Thermogravimetric analysis (TG and DTG) was employed to examine the heat decomposition of these compounds. DFT/B3LYP method, a molecular modeling methodology, is used to support the expected shape of the produced ligand. Chemical hardness and softness, HOMO and LUMO energy levels, electrophilic index, bond lengths, angles, dipole moment, electronegativity, and other factors were calculated. Against HepG‐2 cell line, the in vitro anticancer activity of all chelates and free ligands was evaluated. These synthesized compounds showed good effectiveness. Additionally, DPPH scavenging was used to assess antioxidant activity, with extremely positive results. Molecular docking with the hepatic protein receptor 3ELJ was used to confirm the anticancer results. Finally, the effectiveness of the current thiophene ligand's ability to block Al‐Si alloys in 1 M HCl solution was examined utilizing electrochemical methods. The high inhibition efficiency was obtained revealing the effectiveness of using this thiophene Schiff base ligand on an industrial scale.

Recent Developments in Functional Polymers via the Kabachnik–Fields Reaction: The State of the Art

Recently, multicomponent reactions (MCRs) have attracted much attention in polymer synthesis. As one of the most well-known MCRs, the Kabachnik–Fields (KF) reaction has been widely used in the development of new functional polymers. The KF reaction can efficiently introduce functional groups into polymer structures; thus, polymers prepared via the KF reaction have unique α-aminophosphonates and show important bioactivity, metal chelating abilities, and flame-retardant properties. In this mini-review, we mainly summarize the latest advances in the KF reaction to synthesize functional polymers for the preparation of heavy metal adsorbents, multifunctional hydrogels, flame retardants, and bioimaging probes. We also discuss some emerging applications of functional polymers prepared by means of the KF reaction. Finally, we put forward our perspectives on the further development of the KF reaction in polymer chemistry.

Comparative Solution Equilibrium Studies on Anticancer Estradiol-Based Conjugates and Their Copper Complexes

Steroids are often considered valuable molecular tools for the development of anticancer agents with improved pharmacological properties. Conjugation of metal chelating moieties with a lipophilic sterane backbone is a viable option to obtain novel anticancer compounds. In this work, two estradiol-based hybrid molecules (PMA-E2 and DMA-E2) with an (N,N,O) binding motif and their Cu(II) complexes were developed. The lipophilicity, solubility, and acid-base properties of the novel ligands were determined by the combined use of UV-visible spectrophotometry, pH-potentiometry, and 1H NMR spectroscopy. The solution speciation and redox activity of the Cu(II) complexes were also investigated by means of UV-visible and electron paramagnetic resonance spectroscopy. Two structurally analogous ligands (PMAP and DMAP) were also included in the studies for better interpretation of the solution chemical data obtained. Three pKa values were determined for all ligands, revealing the order of the deprotonation steps: pyridinium-NH+ or NH(CH3)2+, secondary NH2+, and OH. The dimethylamine derivatives (DMA-E2, DMAP) are found in their H2L+ forms in solution at pH 7.4, whereas the fraction of the neutral HL species is significant (34–37%) in the case of the pyridine nitrogen-containing derivatives (PMA-E2, PMAP). Both estradiol derivatives were moderately cytotoxic in human breast (MCF-7) and colon adenocarcinoma (Colo-205) cells (IC50 = 30–63 μM). They form highly stable complexes with Cu(II) ions capable of oxidizing ascorbate and glutathione. These Cu(II) complexes are somewhat more cytotoxic (IC50 = 15–45 μM) than their corresponding ligands and show a better selectivity profile.

Effect of dimercaptosuccinic acid against lead-induced clastogenicity and enzyme activity in mice in-vivo

Indiscriminate exposure of humans to heavy metal contamination via occupation and enviro nmental pollution has been reported with its attendant health burdens including genetic mutation and cancer. This study examined effect of dimercaptosuccinic acid (DMSA) a metal chelator against lead-induced mutagenicity in mice and resultant effect on proper formation of erythrocyte cells. Lead acetate (2.5 mg/kg b.wt) and DMSA (25 mg/kg b.wt) were fed to the mice via oral gavage for 14 consecutive days. Clastogenic effects were observed in the bone marrow cells using micronucleus assay while activity of gamma glutamyl transferase (ý-GT) in both serum and liver was evaluated and the hematologic state of the mice was also monitored. The results obtained indicate that group B animals fed with lead acetate only, significantly (P<0.05) induced the formation of micronucleated polychromatic erythrocytes (mPCEs) in bone marrow of mice compared with control. However, in group C animals fed simultaneously with lead acetate and DMSA, the frequency of micronucleated polychromatic erythrocytes was significantly (P<0.05) reduced while there was marked reduction in levels of hematologic parameters in group D animals. Results from enzyme assay showed that treatment with DMSA resulted in decrease activities for both liver and serum gamma glutamyl transferase with highest mean values of 5.02 U/L and 4.38 U/L respectively. This study underscores the cytotoxicity of lead acetate and ameliorative effect of DMSA with great respite from organic alternative therapy.

Phytochemical analyses by LC-HRMS, FTIR spectral analysis, antioxidant, antidiabetic and antityrosinase activity of Crataegus orientalis Pall. ex M. Bieb fruit extracted with various solvents.

Crataegus orientalis Pall. ex M. Bieb fruit (COPMB) is extensively used as a source of various products in the medicinal-aromatic field and holds the potential for erosion control, ornamental purposes, food source, and economic benefits for forest villagers from its fruits. This study aims to determine the chemical components and biological activities of extracts prepared from COPMB using different solvents. The present work was designed to define the antioxidant activity [phosphomolybdenum (total antioxidant capacity), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), ferric reducing antioxidant power (FRAP), cupric ion-reducing antioxidant capacity (CUPRAC) and metal chelating activity (MCA)], phytochemical screening analysis, enzyme inhibitor (α-amylase, α-glucosidase and tyrosinase) potential, and liquid chromatography-high resolution mass spectrometry (LC-HRMS) secondary metabolite profiling in different extracts of COPMB. The results of LC-HRMS revealed that fumaric acid was the main phenolic compound in all extracts. Among the extracts, ethyl acetate extract has the highest phytochemical and antioxidant properties [total phenolic content (TPC): 32.5 mg GAE/g, total flavonoid content (TFC): 12.2 mg QE/g, ABTS: 213.0 mg TE/g; CUPRAC: 126.0 mg TE/g, MCA: 145.0 mg EDTA/g; FRAP: 122.8 mg TE/g; TAC: 2.8 mmol TE/g]. Ethyl acetate and methanol extracts are more effective in α-amylase (0.27 ± 0.01 mg/mL; 0.12 ± 0.00 mg/mL), α-glucosidase (0.63 ± 0.02 mg/mL; 0.77 ± 0.02 mg/mL) and tyrosinase (0.03 ± 0.00 mg/mL; 0.03 ± 0.00 mg/mL) enzyme inhibition potentials compared to standard acarbose (0.75 ± 0.02 mg/mL for α-amylase; 1.11 ± 0.03 mg/mL for α-glucosidase) and kojic acid (0.04 ± 0.00 mg/mL). The findings from this study suggest that COPMB could serve as a valuable source of natural agents for the food and pharmaceutical industry. © 2024 Society of Chemical Industry.

Low swelling Alginate/Lignin network gels with redox responsiveness for sustained release of agricultural fungicide and Pb2+ complexation

Fungicides are among the most essential agrochemicals for controlling crop diseases. However, the increased consumption of fungicides has resulted in environmental pollution and adversely affected human health. The slow-release technology can improve the efficacy and reduce the required amount of fungicide. Here, we developed a low-swelling redox-responsive alginate/lignin network bearing covalently conjugated fungicide thymol-Cl. Natural reductants in the environment caused the selective cleavage of disulfide bonds and release of thymol-Cl and thiazolidin-2-one (a by-product), which both could inhibit the phytopathogenic fungus (F. oxysporum). At the same time, metal chelating groups in the gel endow strong interactions with heavy metal ions for improving soil remediation and preventing the adsorption of toxic metals by the plant roots. The fungicide-loaded carrier could alleviate the poisonous effect of fungi on maize seeds. Indeed, the secretion of natural reducing agents by fungi and maize led to the cleavage of disulfide bonds and the release of fungicides.

Factors influencing cadmium accumulation in plants after inoculation with rhizobacteria: A meta-analysis

Rhizobacteria have the potential to enhance phytoremediation by generating substances that stimulate plant development and influence the effectiveness of cadmium (Cd) remediation by adjusting Cd availability via metal solubilization. Furthermore, rhizobacterial inoculation affects plants' metal tolerance and uptake by controlling the expression of several metal transporters, channels, and metal chelator genes. A meta-analysis was conducted to quantitatively assess the effects of rhizobacteria on Cd accumulation in plants using 207 individual observations from 47 articles. This meta-analysis showed an average Cd concentration increase of 8.09 % in plant cells under rhizobacteria treatment. The effects of different plant-microbial interactions on the bioaccumulation of Cd in plants varied. Selecting the proper rhizobacteria-plant association is essential to affect Cd buildup in plant roots and shoots. A more extended planting period (>30 days) and a suitable soil pH (<6, 7–8) would aid in the phytoextraction of Cd from the soil. This study comprehensively and quantitatively investigated the effects of plants, rhizobacteria, soil pH, planting period, experimental sites, and plant organs on plant Cd accumulation. According to the analysis of explanatory factors, plant species, planting period, soil pH, and rhizobacteria species have a more decisive influence on Cd accumulation than other factors. The results provide information for future research on the successful remediation of soils contaminated with Cd. More investigations are required to elucidate the intricate interactions between plant roots and microorganisms.

Comparative assessment of phenolic composition profile and biological activities of green extract and conventional extracts of Salvia sclarea

In recent years, there have been an attempt to develop safe and environmental friendly solvents to replace conventional solvents, and use for extraction bioactive compounds from natural sources. A current investigation involved the preparation of green, methanolic, and ultrasonic extracts of S. sclarea, and compared their phenolic profiling using HPLC–DAD, antibacterial, antioxidant, and enzyme inhibition activities. The HPLC–DAD analysis revealed that Rosmarinic acid was the main content in all extracts, with Ellagic acid only present in the green extract. The green extract exhibited superior anti-biofilm activity against S. Aureus and E. Faecalis compared to the other extracts at MIC concentration. Furthermore, the green extract also displayed the highest inhibition of swarming motility in P. Aeruginosa with inhibition range 68.0 ± 2.1 (MIC) to 19.5 ± 0.6 (MIC/4). and better enzyme inhibitory activity against BChE (with IC50 = 131.6 ± 0.98 µg/mL) and AChE (with inhibition 47.00 ± 1.50%) compared to the other extracts; while, the ultrasonic extract showed strong inhibition of violacein production by C. Violaceum with a inhibition range 05.5 ± 0.1 (MIC/32) to 100 ± 0.00 (MIC), followed by the green extract with a inhibition range 15.0 ± 0.5 (MIC/8) to 100 ± 0.00 (MIC), additionally, the ultrasonic and methanoic extracts showed significant activity against urease enzyme with (IC50 = 171.6 ± 0.95 µg/mL and IC5 0 = 187.5 ± 1.32 µg/mL) respectively. Both the green and methanolic extracts showed considerable antioxidant activities, as β-carotene-linoleic acid (IC50 = 5.61 ± 0.47 µg/mL and 5.37 ± 0.27 µg/mL), DPPH· (IC50 = 19.20 ± 0.70 µg/mL and 16.31 ± 0.23 µg/mL), ABTS·+(IC50 = 8.64 ± 0.63 µg/mL and 6.50 ± 0.45 µg/mL) and CUPRAC (A0.5 = 17.22 ± 0.36 µg/mL and 12.28 ± 0.12 µg/mL) respectively, likewise the green extract performing better in metal chelating compared to the other extracts. The green extraction is reported as a cost effective and solvent free method for extracting natural products that produces compounds free of toxic chemicals. This could be the method to be used in the industries as a renewable method.

Development of Fluorescent Chemosensors for Calcium and Lead Detection.

In the present work, several coumarin-3-carboxamides with different azacrown ether moieties were designed and tested as potential luminescent sensors for metal ions. The derivative containing a 1-aza-15-crown-5 as a metal chelating group was found to yield the strongest response for Ca2+ and Pb2+, exhibiting an eight- and nine-fold emission increase, respectively, while other cations induced no changes in the optical properties of the chemosensor molecule. Job's plots revealed a 1:1 binding stoichiometry, with association constants of 4.8 × 104 and 8.7 × 104 M-1, and limits of detection of 1.21 and 8.04 µM, for Ca2+ and Pb2+, respectively. Computational studies suggest the existence of a PET quenching mechanism, which is inhibited after complexation with each of these two metals. Proton NMR experiments and X-ray crystallography suggest a contribution from the carbonyl groups in the coumarin-3-carboxamide fluorophore in the coordination sphere of the metal ion.

Effects of Setaria viridis on heavy metal enrichment tolerance and bacterial community establishment in high-sulfur coal gangue

Plant enrichment and tolerance to heavy metals are crucial for the phytoremediation of coal gangue mountain. However, understanding of how plants mobilize and tolerate heavy metals in coal gangue is limited. This study conducted potted experiments using Setaria viridis as a pioneer remediation plant to evaluate its tolerance to coal gangue, its mobilization and enrichment of metals, and its impact on the soil environment. Results showed that the addition of 40% gangue enhanced plant metal and oxidative stress resistance, thereby promoting plant growth. However, over 80% of the gangue inhibited the chlorophyll content, photoelectron conduction rate, and biomass of S. viridis, leading to cellular peroxidative stress. An analysis of metal resistance showed that endogenous S in coal gangue promoted the accumulation of glutathione, plant metal chelators, and non-protein thiols, thereby enhancing its resistance to metal stress. Setaria viridis cultivation affected soil properties by decreasing nitrogen, phosphorus, conductivity, and urease and increasing sucrase and acid phosphatase in the rhizosphere soil. In addition, S. viridis planting increased V, Cr, Ni, As, and Zn in the exchangeable and carbonate-bound states within the gangue, effectively enriching Cd, Cr, Fe, S, U, Cu, and V. The increased mobility of Cd and Pb was correlated with a higher abundance of Proteobacteria and Acidobacteria. Heavy metals, such as As, Fe, V, Mn, Ni, and Cu, along with environmental factors, including total nitrogen, total phosphorus, urease, and acid phosphatase, were the primary regulatory factors for Sphingomonas, Gemmatimonas, and Bryobacter. In summary, S. viridis adapted to gangue stress by modulating antioxidant and elemental enrichment systems and regulating the release and uptake of heavy metals through enhanced bacterial abundance and the recruitment of gangue-tolerant bacteria. These findings highlight the potential of S. viridis for plant enrichment in coal gangue areas and will aid the restoration and remediation of these environments.

Dual-use of sodium alginate to prepare sodium algenate -derived carbon dots sodium algenate hydrogel composite for Pb2+ removal

The effective mitigation of the environmental impact of heavy metal remains a significant scientific challenge. In this study, a novel and environmentally friendly approach has been proposed to fabricate three-dimensional (3D) functional composite materials for Pb(II) removal. The easy-to-recycle spherical adsorbent is prepared by the dual utilization of sodium alginate (SA) as a bio-source precursor for the synthesis of carbon dots (CDs) and as a natural framework for the formation of SA hydrogel. The abundant surface-active groups on the SA hydrogel not only provide additional adsorption sites for the aggregation of heavy metal ions but can also be readily cross-linked with CDs without chemical additives, and thereby offering a 3D porous structure for chelating metal ions. The resulting HL-5CDs adsorbent demonstrates an impressive adsorption capacity of 305.21 mg·g−1 for Pb(II). The adsorption mechanism involves both chemical reaction and diffusion, leveraging the porous structure and rich oxygen groups of the material. Notably, a pot experiment revealed that the as-prepared HL-5CDs could inhibit the bioavailability of Pb(II). This study introduces a green and straightforward method for creating high-performance adsorbents, showcasing potential applications in energy, cleaning, and the remediation of wastewater pollution.

Synergistic of UV resistant water-borne polyurethane sizing with metal chelation to enhance the interfacial properties of CF/PA6 composites

Currently, the challenge of achieving robust adhesion between carbon fibers and resins remains a focal point for exploring composites. This study introduces a waterborne polyurethane sizing agent employing natural biomass derived sodium alginate as the foundational material. The infusion of 4,4-dihydroxybenzophenone as a chain ext ender imparts the sizing agent with ultraviolet (UV) absorption capabilities. Additionally, chelation between Ca2+ and sodium alginate was harnessed to amplify the interfacial adhesion between the fibers and sizing agent, thereby fostering a more tenacious connection for the two entities and fortifying the fiber-resin interface. The ramifications of varying sizing agent concentrations on composite materials were methodically explored. Comparative analysis conducted against untreated CF composites discloses noteworthy enhancements in the interlaminar shear strength (ILSS) by 46 %, bending strength by 67 %, and interface shear strength (IFSS) by 57 % for CF-1.5 wt%/PA6 composites. Notably, even after enduring a week of xenon lamp aging, the mechanical integrity preserved at approximately 98 %. This inventive methodology presents a fresh avenue for bolstering the characteristics of CF composites.

In vitro research to evaluate the antioxidant effects, inhibiting enzymes, methicillin-resistant Staphylococcus aureus strains of Terminalia catappa extracts

AimContribute to the well-being of the Ivorian population through scientific proof of the use of Terminalia cattapa leaves extracts in traditional medicine. MethodologyThe antioxidative effect of aqueous, water-alcoholic, ethyl acetate and hexane derivatives of Terminalia catappa leaves was measured by six tests: DPPH (2-diphenyl-1-picrylhydrazyl), ABTS (2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)), FRAP (ferric ion reducing antioxidant power), PPBD (phosphomolybdenum), CUPRAC (cupric ion reducing antioxidant capacity) and MCA (metal chelating activity). The inhibition of the activity of five enzymes (acetylcholinesterase, butyrylcholinesterase, tyrosinase, amylase and glucosidase) was also determined. In addition, the broadcast method was used to evaluate impact of the samples on methicillin-resistant Staphylococcus aureus (MRSA) strains. ResultsHighest antioxidant capacity was obtained in the ethanolic sample for DPPH, ABTS, FRAP and PPBD tests. Ethyl acetate sample produced the best CUPRAC and MCA tests. Among inhibitory effect of samples on the five enzymes, aqueous sample showed the strongest anti-acetylCholynesterase and anti-butyrylCholynesterase activity. Best anti-tyrosinase and anti-amylase activity were obtained with the ethanolic sample. Hexane sample obtained the best anti-glucosidase activity while ethanolic and aqueous samples obtained none. All extracts showed no activity on the MRSA strains tested. ConclusionThe chemical compounds present in Terminalia cattapa leaves extracts would not be responsible for the use made in traditional medicine against infections.

Deactivation of porphyrin metal-organic framework in advanced oxidation process: Photobleaching and underlying mechanism

Porphyrin metal-organic frameworks (MOFs) are widely used in photocatalytic advanced oxidation processes (AOP). However, the stability and deactivation of MOFs, crucial for reusability, have been understudied compared to their catalytic activity. We investigated photobleaching in porphyrin MOFs PCN-224-M (M= H2, Fe, Co, Cu, Zn) under visible light and H2O2. The MOFs exhibited crystallinity loss, ring-opening cleavage, and linker degradation. Photobleaching resulted from direct redox reactions between porphyrin sites and H2O2. Metal-oxo-porphyrin intermediates played a key role in the "group effect," with different functional groups affecting the photobleaching rate: PCN-224-Fe ≈ PCN-224-Co > PCN-224-H2 > PCN-224-Cu ≈ PCN-224-Zn. This trend related to chelated metal ions' electronic structures and their propensity for metal-oxo intermediate formation, establishing a structure-stability relationship. Our study enhances understanding of deactivation mechanisms in porphyrin MOFs during AOP, aiding the design of resilient and efficient MOF catalysts for environmental applications.

Biological assays, electrochemical behavior, and theoretical DFT calculations of Ru(II) complexes of chiral phosphinite based based on β-amino alcohols: Transfer hyrogenation of ketones using a HCOOH/Et3N mixture

Synthesis of two phosphinite ligands based on β-amino alcohols, in high yields has been demonstrated. When we treated [Ru(arene)(μ-Cl)Cl]2 {arene:p-cymene,benzene} with chelating phosphinite ligands, we obtained neutral Ru(II)-complexes possessing the general formula [Ru(arene)phosphiniteCl2]. The structure of the ligands and complexes was confirmed using analytical and spectroscopic techniques. The quantum chemical calculations were carried out for the ruthenium complexes at the DFT/CAM-B3LYP level of theory in gas phase. The phosphinite complexes were subjected to cyclic voltammetry studies in order to determine the energies of HOMO and LUMO levels and to estimate their electrochemical and some electronic properties. Organic complex-based memory substrates were immobilized using TiO2-modified ITO electrodes, and the memory functions of phosphinite-based organic complexes were verified by chronoamperometry (CA) and open-circuit potential amperometry (OCPA). In the present study, the antioxidant potentials of ruthenium-based p-cymene and benzene complexes through DPPH radical scavenging, metal chelating, and reducing power activities were also determined. In addition, DNA binding abilities and antimicrobial activities of these complexes against pathogenic bacteria were studied. Finally, the ruthenium complex, (2S)-1-{[(2S)-2-[(diphenylphosphanyl)oxy]propyl][(1R)-1-phenylethyl]amino}propan-2-yldiphenyl phosphinitobis[dichloro(η6-benzene)ruthenium(II)] also catalyzed asymmetric transfer hydrogenation of acetophenone with high conversion (up to 99%) and good enantioselectivity (ee up to 89 %), in the existence of formic acid and triethylamine in dichloromethane medium under air atmosphere.