Complexation Of Zinc Ions Research Articles

Green Synthesis of Nanoparticles Containing Zinc Complexes and Their Incorporation in Topical Creams with Antimicrobial Properties

This article reports on a new way of valorizing vine leaves waste as a renewable resource of polyphenols. The nanoparticles containing zinc complexes were prepared by a green synthesis method using the aqueous extract of vine leaves as a natural source of ligands for the complexation of zinc ions. The prepared nanoparticles were characterized by UV-Vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) in conjunction with energy dispersive X-ray spectroscopy (EDX). Another objective of this study was to obtain a cream into which the biosynthesized nanoparticles would be incorporated. In the formulation of the new cream, we aimed to use the minimal required amounts of synthetic emulsifiers and to use natural products as co-emulsifiers or as viscosity modifiers. The organoleptic characteristics and the physicochemical properties of the obtained creams were evaluated. The experimental results confirmed that the creams wherein the nanoparticles containing zinc complexes were incorporated exhibited antimicrobial activity against the bacterial species Staphylococcus aureus, methicillin-resistant Staphylococcus aureus, Escherichia coli and the yeast Candida albicans. The values obtained for pH, viscosity and spreading diameter of the creams produced indicate that these formulations are suitable for topical applications.

A paper-based ratiometric fluorescent sensor for NH3 detection in gaseous phase: Real-time monitoring of chilled chicken freshness

A ratiometric fluorescence sensor platform with easy-to-use and accurate is nanoengineered for NH3 quantitative detection and visual real-time monitoring of chicken freshness using smartphones. The ratiometric fluorescent probe formed by combining the zinc ion complex and carbon dots has a double-emitted fluorescence peak. The fluorescence intensity of the complex changed can be clearly observed with the increase of the concentration of ammonia solution under 365 nm wavelength excitation. In order to detect NH3 concentration in gaseous phase, a portable paper-based sensor was designed. The sensor had a good linear relationship with NH3 concentration ranging from 10.0 to 90.0 μmol/L and the LOD value was 288 nM. This fluorescent paper-based sensor was used to check the freshness of chicken breast refrigerated at 4 °C, revealed observable shifts from blue to green. The fluorescent paper-based sensor can detect NH3 concentration in real time and simplify the monitoring process of meat freshness while ensuring accuracy and stability.

Deciphering the complexes of zinc ions and hen egg white lysozyme: Instrumental analysis, molecular docking, and antimicrobial assessment

In the research presented in this manuscript, an intricate study has been carried out on the interaction of zinc ions with the hen egg white lysozyme (HEWL) protein. Utilizing a spectroscopic technique, the alterations that arise due to the binding of Zn2+ to the HEWL were scrutinized, underscoring the paramount significance of deprotonated carboxyl and thiol groups in the process of binding. The binding phenomena were substantiated using capillary electrophoresis integrated with inductively coupled plasma mass spectrometry (CE-ICP-MS). Further spectrometric assessments (MALDI-TOF MS and FT-ICR-MS) shed light on the direct interaction of zinc ions with the functional groups of the protein. Importantly, high-resolution FT-ICR-MS techniques elucidated the capability of a single protein molecule to bind to multiple zinc ions. The empirically derived spectroscopic data received additional confirmation via a molecular docking study of the Zn2+ binding process, which highlighted a substantial affinity between the predicted 3D model of zinc-lysozyme complexes. Predominantly, the interaction between the bound entities was observed at the cysteine residues. Lastly, the conducted antimicrobial tests revealed that the zinc-lysozyme complexes manifest an inhibitory effect against bacterial (E. coli and S. aureus) and yeast (C. albicans) strains.

Copper(II), Cobalt(II), Nickel(II) And Zinc(II) Complexes Obtained From Dipicolinic Acid And Morpholine: Synthesis, Characterization, Biological Evaluation And In Silico Studies

With morpholinium counter ion a set of new complexes of Copper(II), Cobalt(II), Nickel(II) and Zinc(II) ions were synthesized and characterized. UV-visible, IR, powder XRD and thermal studies have been utilized to characterize the synthesized complexes. The structures of the complexes were optimized using DFT studies and screened for their antioxidant and anti-inflammatory activities. The results of In vitro antioxidant and anti-inflammatory activity studies indicated the appreciable biological activity of the synthesized complexes. All the synthesized complexes exhibited very good stability under physiological conditions for 72 h. Molecular docking studies performed with cyclooxygenase enzymes (COX-1 and COX-2) revealed the significant interaction between the complexes and the enzymes through many hydrogen bonds with very good binding energies.

Core‐Shell Nanospheres with Controllable Zinc Ion Release for Time‐Sensitive Steganography

AbstractSlow‐release platforms have attracted much attention due to their many applications, such as biomedical implants, plant fertilizers, and drug delivery systems. In this work, a green, cost‐effective, and scalable method is reported to synthesize colloidal hybrid nanospheres capable of releasing zinc ions in a highly controllable manner by encapsulating zinc ammonium citrate colloids with a layer of silica. The release rate of zinc ions from resulting core‐shell nanospheres can be conveniently tuned by changing the shell thickness and cross‐linking degree of the silica layer, the solvent composition, and the surrounding temperature. By integrating the temperature‐sensitive release behavior of the hybrid nanospheres, the color shift associated with the complexation of zinc ions with xylenol orange, and the photothermal conversion property of gold nanoparticles, a novel film capable of recording time‐sensitive color information is designed using direct laser writing and further demonstrated its application in steganography.

The Role of Side Chains in the Fine-Tuning of the Metal-Binding Ability of Multihistidine Peptides

The systematic studies of copper(II), nickel(II) and zinc(II) ion complexes of protected multihistidine peptides containing amino acids with different side chains (Ac-SarHAH-NH2, Ac-HADH-NH2, Ac-HDAH-NH2, Ac-HXHYH-NH2 X, Y = A, F, D or K, Ac-HXHAHXH-NH2, X = F or D) have provided information about the metal ion and protein interaction and have made it possible to draw conclusions regarding general trends in the coordination of metal complexes of multihistidine peptides. The stability of the metal complexes significantly depends on the position of the histidines and amino acids, which are present in the neighbourhood of the histidine amino acids as well. The most significant effect was observed on peptides containing aspartic acid or phenylalanine. The redox parameters of complexes, however, depend on the number and position of histidines, and the other side chain donor atoms have practically no effect on the electrochemical properties of imidazole-coordinated species. However, the presence of aspartic acid side chains results in a more distorted geometry of amide-coordinated species and increases the reducibility of these complexes.

Ligating Properties and Antimicrobial Studies of Metal (II) Complexes of Amoxicillin

Researchers in recent years are working on different approaches to the problem of bacteria resistant to antibiotics through drug modification. The synthesis of metal drug complexes are becoming more popular than their parent drugs because they possess modified pharmacological, toxicological and physiochemical properties. In this study, amoxicillin complexes of copper and zinc (II) ions were synthesized using standard method. The complexes were characterized for aqueous solubility, UV-visible spectral, acid stability, and thermal stability and in-vitro antimicrobial activities. The results of the physiochemical properties showed evidence of complex formation between the metals and the ligand. The acid and thermal stability of amoxicillin complexes showed high acid and thermal stability than its parent form. In-vitro antimicrobial activity of amoxicillin and its complexes form were studied against Staphylococcus aureus and Pseudomonas aeruginosa. The results revealed that Amoxicillin complexes of copper (II) ions showed effective antibacterial effect on Staphylococcus aureus than its pure form while Amoxicillin Zn2+ showed lower antibacterial activity when compared to its parent drug. This study suggests that transition metal complexes of amoxicillin modify the properties of the parent drug.

How Structural Biology Has Directly Impacted Our Understanding of P2X Receptor Function and Gating.

P2X receptors are ATP-gated ion channels expressed in a wide variety of eukaryotic cells. They play key roles in diverse processes such as platelet activation, smooth muscle contraction, synaptic transmission, nociception, cell proliferation, and inflammation making this receptor family an important pharmacological target. Structures of P2X receptors solved by X-ray crystallography have been instrumental in helping to define mechanisms of molecular P2X receptor function. In 2009, the first X-ray structure of the P2X4 receptor subtype confirmed a trimeric stoichiometry and revealed the overall architecture of the functional ion channel. Subsequent X-ray structures have provided the molecular details to define the orthosteric ATP binding pocket, the orthosteric antagonist binding pocket, an allosteric antagonist binding pocket, and the pore architecture in each of the major conformational states of the receptor gating cycle. Moreover, the unique gating mechanism by which P2X receptor subtypes desensitize at differing rates, referred to as the helical recoil model of receptor desensitization, was discovered directly from X-ray structures of the P2X3 receptor. However, structures of P2X receptors solved by X-ray crystallography have only been able to provide limited information on the cytoplasmic domain of this receptor family, as this domain was always truncated to varying degrees in order to facilitate crystallization. Because the P2X7 receptor subtype has a significantly larger cytoplasmic domain that has been shown to be necessary for its ability to initiate apoptosis, an absence of structural information on the P2X7 receptor cytoplasmic domain has limited our understanding of its complex signaling pathways as well as its unusual ability to remain open without undergoing desensitization. This absence of cytoplasmic structural information for P2X7 receptors was recently overcome when the first full-length P2X7 receptor structures were solved by single-particle cryogenic electron microscopy. These structures finally provide insight into the large and unique P2X7 receptor cytoplasmic domain and revealed two novel structural elements and several surprising findings: first, a cytoplasmic structural element called the cytoplasmic ballast was identified that contains a dinuclear zinc ion complex and a high affinity guanosine nucleotide binding site and second, a palmitoylated membrane proximal structural element called the C-cys anchor was identified which prevents P2X7 receptor desensitization. This chapter will highlight the major structural and functional aspects of P2X receptors discovered through structural biology, with a key emphasis on the most recent cryogenic electron microscopy structures of the full-length, wild-type P2X7 receptor.

Cathode materials for aqueous zinc-ion batteries: A mini review

Although lithium-ion batteries (LIBs) have many advantages, they cannot satisfy the demands of numerous large energy storage industries owing to their high cost, low security, and low resource richness. Aqueous zinc-ion batteries (ZIBs) with low cost, high safety, and high synergistic efficiency have attracted an increasing amount of attention and are considered a promising choice to replace LIBs. However, the existing cathode materials for ZIBs have many shortcomings, such as poor electron and zinc ion conductivity and complex energy storage mechanisms. Thus, it is crucial to identify a cathode material with a stable structure, substantial limit, and suitability for ZIBs. In this review, several typical cathode materials for ZIBs employed in recent years and their detailed energy storage mechanisms are summarized, and various methods to enhance the electrochemical properties of ZIBs are briefly introduced. Finally, the existing problems and expected development directions of ZIBs are discussed.

The preparation of antibacterial eco-friendly bio-based PTT-based β-cyclodextrin by complexation of copper and zinc ions

There has been an increasing focus on antibacterial textiles owing to their widespread applications in global public health. In this study, we prepared antibacterial bio-based poly (trimethylene terephthalate) (PTT) by multi-crosslinking with citric acid among PTT and β-cyclodextrin (β-CD), and then adsorbing zinc and copper ions. The results show that β-cyclodextrin was successfully grafted onto the surface of PTT. The adsorption amounts of Zn2+ and Cu2+ on β-CD/PTT were investigated by ICP and FE-SEM, which showed that Zn2+ and Cu2+ penetrated the fabric surface. Moreover, under optimal adsorption conditions, the adsorption capacity of Zn2+ and Cu2+ are about 34 mg/g and 50 mg/g, respectively. During antibacterial test, the bactericidal rates of β-CD/Cu2+/PTT reached 90.75% for E. coli and 85.36% for S. aureus, and the bactericidal rates of β-CD/Zn2+/PTT are 80.48% for E. coli and 73.10% for S. aureus. Functionalized PTT fabrics with eco-environmental and sustainable performance may have promising application in the field of antibacterial fabrics.

2′-Thiophenecarboxaldehyde derived thiosemicarbazone metal complexes of copper(II), palladium(II) and zinc(II) ions: Synthesis, spectroscopic characterization, anticancer activity and DNA binding studies

Heterocyclic 5′-methyl-2-thiophenecarboxaldehyde-N(4)-un/substituted thiosemicarbazones (1–3) and their metal complexes with copper(II), palladium(II) and zinc(II) ions (4–11) were synthesized and characterized by using different spectroscopic techniques like FT-IR, 1H, 13C NMR, UV–Visible and electron paramagnetic spectroscopy, etc. The crystal structures of the synthesized thiophene thiosemicarbazone ligands 1, 2 and 3 were determined unambiguously by single-crystal X-ray diffraction analysis. The EPR spectra of the copper(II) complexes, 4, 6 and 9 have shown rhombic, normal axial and inverse axial symmetry respectively. Furthermore, the DNA binding study was performed on calf-thymus DNA by absorbance, fluorescence and viscosity measurement methods. Notably, the copper(II) and palladium(II) complexes have strong DNA binding interactions compared to the zinc(II) complexes. The DNA binding constants measured for these complexes were found to be in the range of 1.83 × 104–1.45 × 105 M−1. Further, the newly synthesized complexes were also tested for their in vitro anticancer activity against three types of human cancer cell lines (COLO-205, MCF-7 and HepG-2) and one normal cell line (HEK-293). Importantly, the zinc(II) complex (8) exhibited potent anticancer activity against HepG-2 with an IC50 value of 11.65 ± 1.753 µM compared to the standard drug cis-platin. The copper(II) complex, 9 against COLO- 205 with an IC50 value of 23.08 ± 1.354 µM, complex 4 against MCF-7 and HepG-2 with IC50 values of 39.35 ± 1.825 µM and 35.26 ± 0.354 µM, respectively, and complex 6 against HepG-2 with an IC50 value of 38.30 ± 1.385 µM have displayed moderate activity compared to the reference drug cis-platin.

Zinc(II)-Dipicolylamine Analogs Mediated PEI1.8k/pDNA Vector: Effect of Ligand Structure on the Gene Transport Process.

Zinc ion complexes of dipicolylamine analogs, due to the strong synergistic effect between the Zn2+ complex of containing polypyridine derivatives and polycations in each key step of pDNA transport, have been used as the third component to mediate polyethyleneimine with molecular weight 1.8kDa (PEI1.8k)/DNA gene delivery system. And the effects of different structural characteristics, such as the number of pyridinamine ligands, the hydrophilic-hydrophobicity of the adjacent groups, on the in vitro transfection performance of the ternary complex are systematically investigated. This ternary hybrid system provides an effective strategy to improve the gene delivery of cationic polymers.

Zn composite corrosion resistance coatings: What works and what does not work?

Corrosion is one of the most significant contributors to structural degradation in process industries. It causes process equipment failure, which can led to severe safety issues. One approach to address this concern is to provide a preventive barrier-coating to equipment. Due to its superior reductive property, zinc is usually employed as a sacrificial anode in conventional corrosion-resistance methods. Nickel is also used to both mechanically strengthen the barrier and improve overall corrosion resistance; therefore, zinc, zinc-nickel alloys, and zinc-nickel-oxide composite coatings are commonly employed for anti-corrosion purposes. The complexation of zinc and nickel ions by agents (citrate, acetate and EDTA) can stabilize the electrodeposition bath and extend the pH of Ni(OH)2 and ZnO precipitation to improve corrosion resistance in the resultant coating. This paper reviews the challenge with these type of coatings and presents progress in Zn and Zn-Ni composite corrosion resistance coatings co-deposited with Al2O3, TiO2, ZrO2, SiO2, and Fe2O3 as means of corrosion control to reduce the probability of process equipment failure due to corrosion, which will improve the overall safety and reliability of processing equipment.

Adsorption properties of nanostructured form of aluminium hydroxide γ-modification

Adsorption properties of aluminium hydroxide γ-modification towards toxic copper(II) and zinc(II) ions were studied. In a neutral medium at pH=7.6, the ion adsorption capacity was 264 mg/g for copper(II) and 338 mg/g for zinc(II). The study of the temperature effect on the absorbability of toxic ions established that the adsorption capacity is characterized by an increase followed by a decrease as the equilibrium value is reached. The absorbability increase in the initial moment is caused by an increase in the formation rate of hydroxo aqua complexes of copper(II) and zinc(II) ions. The differential heat of adsorption was determined. It demonstrated a decrease from 27 to 20 kJ/mol during the process, which is caused by the fact that, as the most active centres of nanostructured form of aluminium hydroxide γ-modification are saturated, heavy metal ions are adsorbed by decreasingly active regions of its surface.

Corrosion behaviour of Zn-Ni alloy and Zn-Ni-nano-TiO2 composite coatings electrodeposited from ammonium citrate baths

Electrochemical and corrosion behaviour analysis of Zn-Ni alloy and Zn-Ni-nanoTiO2 composite coatings electrodeposited on steel from ammonium citrate containing bath was performed. The complexation of zinc and nickel ions in citrate stabilized the electroplating bath. The electrochemical behaviour of samples showed that Zn-Ni alloy with the incorporation of 0.003 mol/l of titania (TiO2) nanoparticles exhibited noble corrosion potential (Ecorr) and decreasing corrosion current (Icorr). This leads to increase impedance modulus with a more compact and durable uniform coating of 25.84 nm grain size. The surface characterization and crystalline phase texture of the coatings were investigated by scanning electron microscopy (SEM) integrated with energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The topographical structure of the coating was analyzed by atomic force microscopy (AFM). The chemical composition result showed that the Zn-Ni+0.003TiO2 coating electrodeposited from a citrate bath in various immersion tests reduced dezincification in the coating. The presence of higher intensity of the γ-phases (γ-NiZn3) (815) and γ-Ni2Zn11 (330) (631) plane orientation and β-Ti phase provide better corrosion resistance performance of the coating. The most significant corrosion products for Zn-Ni alloy electroplating are simonkolleite, hydrozincite, zincite, and wulfingite.

Full-Length P2X7 Structures Reveal How Palmitoylation Prevents Channel Desensitization

P2X receptors are trimeric, non-selective cation channels activated by extracellular ATP. The P2X7 receptor subtype is a pharmacological target because of involvement in apoptotic, inflammatory, and tumor progression pathways. It is the most structurally and functionally distinct P2X subtype, containing a unique cytoplasmic domain critical for the receptor to initiate apoptosis and not undergo desensitization. However, lack of structural information about the cytoplasmic domain has hindered understanding of the molecular mechanisms underlying these processes. We report cryoelectron microscopy structures of full-length rat P2X7 receptor in apo and ATP-bound states. These structures reveal how one cytoplasmic element, the C-cys anchor, prevents desensitization by anchoring the pore-lining helix to the membrane with palmitoyl groups. They show a second cytoplasmic element with a unique fold, the cytoplasmic ballast, which unexpectedly contains a zinc ion complex and a guanosine nucleotide binding site. Our structures provide first insights into the architecture and function of a P2X receptor cytoplasmic domain.

New ternary complexes of zinc ions with glycine and histidine in solution

Mixed-ligand complexes of zinc with glycine (Gly) and histidine (His) have been studied in an aqueous solution at 298.15 K and I = 0.5 (KNO3) using calorimetric and pH-metric data. The thermodynamic parameters of formation of various mixed complexes have been determined. The probable coordination modes of amino acid residues in mixed-ligand complexes have been discussed.

Cover Feature: Isolation and Characterization of Different Homometallic and Heterobimetallic Complexes of Nickel and Zinc Ions by Controlling Molar Ratios and Solvents (Eur. J. Inorg. Chem. 24/2019)

Cover Feature: Isolation and Characterization of Different Homometallic and Heterobimetallic Complexes of Nickel and Zinc Ions by Controlling Molar Ratios and Solvents (Eur. J. Inorg. Chem. 24/2019)

Isolation and Characterization of Different Homometallic and Heterobimetallic Complexes of Nickel and Zinc Ions by Controlling Molar Ratios and Solvents

This work describes employment of two structurally similar Schiff‐base ligands (H2L and H2L‐Me) [H2L = C14H13NO3 and H2L‐Me = C15H15NO3] for the synthesis of three homo‐metallic ZnII and two hetero‐bimetallic ZnII–NiII based multinuclear complexes {[ZnII4L4(MeOH)2] (1), [ZnII5(L)5(MeOH)2]·MeOH·CH3CN (2), [(L)2ZnII4Cl2(µ3‐OMe)2(MeOH)2]·2MeOH (3), [NiII2ZnII2(L)4(MeOH)2] (4) and [Ni3Zn2(L‐Me)5(H2O)2]·MeOH·CH3CN (5)} with different interesting structural core topologies. All of these complexes (1–5) have been characterized by single‐crystal X‐ray diffraction (XRD), elemental analysis, and UV/Vis and Fourier transform infrared (FTIR) spectroscopy. The fluorescence properties of ZnII‐containing complexes have been studied by measuring fluorescence spectra in solid state and solution phase. The luminescence behavior has been further quantified by fluorescence life‐time and quantum yield measurements. Using high resolution mass spectrometry (HR‐MS), the molecular integrity of complexes in the solution phase has been demonstrated by simulating isotopic distribution of molecules with theoretically calculated molecular isotopic patterns. The magnetic properties of ZnII–NiII containing complexes (4–5) have been studied in the temperature range from 5 K to 300 K. Thermogravimetric analysis (TGA) has been carried out to study the thermal stabilities of these complexes (1–5).

Effects of the H6R and D7H Mutations on the Heparin-Dependent Modulation of Zinc-Induced Aggregation of Amyloid β

Zinc ions and glycosaminoglycans (GAGs) are found in amyloid deposits and are known to modulate the β-amyloid peptide (Aβ) aggregation, which is thought to be a key event in the pathogenesis of Alzheimer's disease (AD). Correlation spectroscopy was used to study how the H6R and D7H mutations of the metal-binding domain (MBD) of Aβ42 affect the modulation of its zinc-induced aggregation by the model GAG heparin. The H6R mutation was shown to decrease and the D7H mutation to increase the Aβ42 propensity to aggregate in the presence of zinc ions. In addition, H6R diminished and D7H enhanced the modulating effect of heparin. The difference in the heparin-dependent modulation was associated with coordination of zinc ions within the MBDs of the mutant peptides. The findings indicate that anion-binding sites formed by complexes of zinc ions with the Aβ MBD play an essential role in the interaction of zinc-induced Aβ aggregates with heparin.