Presence Of Zinc Research Articles

A multifunctional leather composite with good antibacterial and hygrothermal management capabilities

If not removed in a timely manner, the large amount of sweat produced by overheated human skin can cause thermal discomfort and health problems. Development of fabrics with cooling and dehumidifying capabilities is advantageous to improving the quality of human life. In this work, a natural leather-based Zn-monoethanolamine@lignin (Zn-MEA@lignin-leather) composite fabric with personal hygrothermal management properties was fabricated by infiltrating the permeable 3D network microstructure of the natural leather collagen fiber bundles with adhering moisture-absorbent hydrogel containing photothermal lignin. Due to the efficiency of the composite hydrogel in trapping water molecules, the fabric can promote evaporation of sweat from overheated skin surfaces. Compared to the conventional textiles, the composite leather fabric can reduce the humidity of simulated skin surface by about 40 % and accelerate the evaporation of sweat from the skin surface to promote reduction in temperature of the overheated body. Thanks to the good photothermal conversion efficiency of lignin, the hydrated composite fabric exhibits a favorable evaporation regeneration rate (0.498 kg m−2 h−1). In addition, the presence of zinc ions in the coordination complex imparts good antimicrobial efficiency to the composite fabric, with inactivation rates approaching 99.99 % for both Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). Thus, the composite leather fabric holds great promise to personal hygrothermal management and healthcare.

Preparation, characterization and microencapsulation of walnut (Juglans regia L.) peptides-zinc chelate.

In this research, a novel kind of walnut (Juglans regia L.) peptides-zinc (Zn-WPs) chelate was obtained using the mass ratio of the walnut peptides (WPs) to ZnSO4.7H2O of 3.5:1 at pH 8.5 and 50°C for 84min, with the chelation rate of 84.5%. In comparison to walnut peptides (WPs), the contents of aspartic acid and glutamic acid in Zn-WPs chelate are approximately 27%, indicating that hydrophilic amino acids predominantly bind with walnut peptides. Following chelation with zinc ions, the ultraviolet-visible (UV) characteristic absorption peak shifted from 213nm to 210nm, while the average particle size of the chelate increased to 8.0±0.14µm, presenting a loose spherical structure under scanning electron microscopy. These findings suggest the formation of new substances. Fourier-transform infrared spectroscopy (FTIR) revealed carboxyl, amino, and peptide bonds as the chelation sites of WPs and zinc. The IC50 of walnut peptides-zinc (Zn-WPs) chelate is 2.91mg/mL, indicative of a favorable DPPH radical scavenging rate. Furthermore, Zn-WPs chelate microcapsules were produced via the spray drying method, achieving an encapsulation rate of 75.67±0.83% under optimal conditions. These microcapsules demonstrate robust stability across diverse environmental conditions. This study underscores the potential of Zn-WPs and its chelate microcapsules to enhance stability and bioactivity under varying circumstances. PRACTICAL APPLICATION: In this study, a new walnut peptide-zinc (Zn-WPs) chelate was prepared. The presence of zinc ions changes the structure and properties of walnut peptides and improves its stability. The production of Zn-WPs chelate microcapsules enables Zn-WPs to have strong in vitro stability under different pH and simulated gastrointestinal digestion conditions. These results provide novel insights for developing the walnut peptides as bioactive ingredients in functional foods.

Role of phosphate in microalgal-bacterial symbiosis system treating wastewater containing heavy metals

Phosphorus is one of the important factors to successfully establish the microalgal-bacterial symbiosis (MABS) system. The migration and transformation of phosphorus can occur in various ways, and the effects of phosphate on the MABS system facing environmental impacts like heavy metal stress are often ignored. This study investigated the roles of phosphate on the response of the MABS system to zinc ion (Zn2+). The results showed that the pollutant removal effect in the MABS system was significantly reduced, and microbial growth and activity were inhibited with the presence of Zn2+. When phosphate and Zn2+ coexisted, the inhibition effects of pollutants removal and microbial growth rate were mitigated compared to that of only with the presence of Zn2+, with the increasing rates of 28.3% for total nitrogen removal, 48.9% for chemical oxygen demand removal, 78.3% for chlorophyll-a concentration, and 13.3% for volatile suspended solids concentration. When phosphate was subsequently supplemented in the MABS system after adding Zn2+, both pollutants removal efficiency and microbial growth and activity were not recovered. Thus, the inhibition effect of Zn2+ on the MABS system was irreversible. Further analysis showed that Zn2+ preferentially combined with phosphate could form chemical precipitate, which reduced the fixation of MABS system for Zn2+ through extracellular adsorption and intracellular uptake. Under Zn2+ stress, the succession of microbial communities occurred, and Parachlorella was more tolerant to Zn2+. This study revealed the comprehensive response mechanism of the co-effects of phosphate and Zn2+ on the MABS system, and provided some insights for the MABS system treating wastewater containing heavy metals, as well as migration and transformation of heavy metals in aquatic ecosystems.

Se-Glargine: Chemical Synthesis of a Basal Insulin Analogue Stabilized by an Internal Diselenide Bridge.

Insulin has long provided a model for studies of protein folding and stability, enabling enhanced treatment of diabetes mellitus via analogue design. We describe the chemical synthesis of a basal insulin analogue stabilized by substitution of an internal cystine (A6-A11) by a diselenide bridge. The studies focused on insulin glargine (formulated as Lantus® and Toujeo®; Sanofi). Prepared at pH 4 in the presence of zinc ions, glargine exhibits a shifted isoelectric point due to a basic B chain extension (ArgB31 -ArgB32 ). Subcutaneous injection leads to pH-dependent precipitation of a long-lived depot. Pairwise substitution of CysA6 and CysA11 by selenocysteine was effected by solid-phase peptide synthesis; the modified A chain also contained substitution of AsnA21 by Gly, circumventing acid-catalyzed deamidation. Although chain combination of native glargine yielded negligible product, in accordance with previous synthetic studies, the pairwise selenocysteine substitution partially rescued this reaction: substantial product was obtained through repeated combination, yielding a stabilized insulin analogue. This strategy thus exploited both (a) the unique redox properties of selenocysteine in protein folding and (b) favorable packing of an internal diselenide bridge in the native state, once achieved. Such rational optimization of protein folding and stability may be generalizable to diverse disulfide-stabilized proteins of therapeutic interest.

Effects of Addition of Lanthanum and Zinc Oxides on the Biological Properties of TiO2-SiO2-P2O5/CaO on Ion Exchange Resin for Bone Implantation.

The spherical materials TiO2-SiO2-P2O5/CaO, TiO2-SiO2-P2O5/La2O3, and TiO2-SiO2-P2O5/ZnO deposited on the Tokem-250 cation exchanger have been synthesized with an alcoholic solution by the sol-gel method. The macroporous cation exchanger Tokem-250, which has high Ca2+, Zn2+, and La3+ ion selectivity, was used in the present study. This material has the ability to precipitate and mineralize calcium phosphates on its surface in biological media, since it has high porosity, a homogeneous structure with a uniform variation of elements, and the presence of active centers (Si4+, Ti4+) on the surface. The effect of lanthanum and zinc additives on biological properties has been studied. It was established that accumulation of Ca2+ and Mg2+ occurs faster on the surface of TiO2-SiO2-P2O5/ZnO in the SBF (simulated body fluid) model solution, showing higher reaction capacity. The amount of calcium and phosphorus ions on the surface of sample TiO2-SiO2-P2O5/La2O3 is greater due to the ability of lanthanum to coordinate a large number of ions (lanthanum coordination number is 10). The presence of zinc ions in the system causes the partial hemoglobin release from erythrocytes into the supernatant fluid. The samples with lanthanum ions reduce the amount of protein in plasma after incubation, which has a positive effect on the practical application.

Nanocomposite Hydrogel Films Based on Sequential Interpenetrating Polymeric Networks as Drug Delivery Platforms.

In this study, novel materials have been obtained via a dual covalent and ionic crosslinking strategies, leading to the formation of a fully interpenetrated polymeric network with remarkable mechanical performances as drug delivery platforms for dermal patches. The polymeric network was obtained by the free-radical photopolymerization of N-vinylpyrrolidone using tri(ethylene glycol) divinyl ether as crosslinker in the presence of sodium alginate (1%, weight%). The ionic crosslinking was achieved by the addition of Zn2+, ions which were coordinated by the alginate chains. Bentonite nanoclay was incorporated in hydrogel formulations to capitalize on its mechanical reinforcement and adsorptive capacity. TiO2 and ZnO nanoparticles were also included in two of the samples to evaluate their influence on the morphology, mechanical properties and/or the antimicrobial activity of the hydrogels. The double-crosslinked nanocomposite hydrogels presented a good tensile resistance (1.5 MPa at 70% strain) and compression resistance (12.5 MPa at a strain of 70%). Nafcillin was loaded into nanocomposite hydrogel films with a loading efficiency of up to 30%. The drug release characteristics were evaluated, and the profile was fitted by mathematical models that describe the physical processes taking place during the drug transfer from the polymer to a PBS (phosphate-buffered saline) solution. Depending on the design of the polymeric network and the nanofillers included, it was demonstrated that the nafcillin loaded into the nanocomposite hydrogel films ensured a high to moderate activity against S. aureus and S. pyogenes and no activity against E. coli. Furthermore, it was demonstrated that the presence of zinc ions in these polymeric matrices can be correlated with the inactivation of E. coli.

Allantoin‑zinc layered simple hydroxide biohybrid as antimicrobial active phase in cellulosic bionanocomposites as potential wound dressings

Cellulosic materials loaded with a novel zinc layered simple hydroxide (LSH) with allantoin in its structure (allant-ZnLSH) have been developed for potential application as wound dressings. The allant-ZnLSH biohybrid was synthesized by slow addition of a zinc chloride solution to an aqueous solution of allantoin, while adding a NaOH solution dropwise to maintain a controlled pH. The recovered precipitate was characterized by XRD, FTIR, chemical analysis, and FE-SEM. The allant-ZnLSH material was further incorporated into biopolymeric matrices such as hydroxypropylmethylcellulose (HPMC), carboxymethylcellulose (CMC) and cellulose nanofibers (CNF), because of their biocompatibility and biodegradability. The resulting films presented suitable mechanical properties, with Young's modulus values ranging between 1.3 and 3.9 GPa, as well as appropriate water vapor transmission rates (WVTR) for application in would healing, around 250–630 g/m2 per day. The bionanocomposite films also showed interesting barrier properties against the passage of UV light, while keeping a certain transparency in the visible range that would allow the healing process to be monitored without removing the dressing. Their antibacterial action was evaluated against E. coli and S. aureus in agar plates, showing only antimicrobial activity against the latter. The goal is to develop materials that can exhibit antimicrobial, and skin regenerative properties provided by the presence of zinc ions and allantoin, respectively.

The T2 structure of polycrystalline cubic human insulin.

The polymorphism of human insulin upon pH variation was characterized via X-ray powder diffraction, employing a crystallization protocol previously established for co-crystallization with phenolic derivatives. Two distinct rhombohedral (R3) polymorphs and one cubic (I213) polymorph were identified with increasing pH, corresponding to the T6, T3R3f and T2 conformations of insulin, respectively. The structure of the cubic T2 polymorph was determined via multi-profile stereochemically restrained Rietveld refinement at 2.7 Å resolution. This constitutes the first cubic insulin structure to be determined from crystals grown in the presence of zinc ions, although no zinc binding was observed. The differences of the polycrystalline variant from other cubic insulin structures, as well as the nature of the pH-driven phase transitions, are discussed in detail.

A new method in the synthesis of conductive polymers; synthesis, characterization, and investigation of photocatalytic properties of polyaniline.

As known, in the synthesis of conductive polyaniline polymer from aniline monomer, the polymerization medium must be acidic. In order to make the polymerization medium acidic, protonic acids such as HCl and H2SO4 are generally used. In this study, two acids have been used to make the polymerization medium acidic. One of them, as we know, is H2SO4 as a protonic acid. The other acid is the zinc ion, which is a Lewis acid. The metal ion has never been used for this purpose up to now. Two polyaniline polymers have been synthesized to prove that conductive polymers can also be synthesized in the presence of metal ions instead of protonic acid. One of them is the polyaniline polymer, synthesized in the presence of H2SO4(PANI). The other polymer is polyaniline polymer, synthesized in the presence of zinc ions as acid (PANI-Zn-PSS). The synthesized polymers have been characterized by using scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDX), X-ray diffraction diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR), Ultraviolet-visible spectrophotometer (UV-vis.), thermal analysis techniques (thermo-gravimetric analysis, TGA)/differential thermal analysis, DTA) and electrical conductivity measurements kit. The photocatalytic activities of polymers synthesized have been investigated by the degradation of methylene blue (MB) dye in aqueous medium under UV light.

Retarding mechanism of Zn2+ species in geopolymer material using Raman spectroscopy and DFT calculations

Geopolymers are the most promising alternative to Ordinary Portland Cement for oil-well cementing and well abandonment. To that end, the slurry needs a required pumping time ensured by the addition of retarders. Although zinc has been widely known to prolong the setting time of geopolymers, its mechanism of action has yet to be fully elucidated. It is herein hypothesized that zinc ions impede the first stages of silicate oligomerization (Si–O–Al), culminating in longer setting times. Pumping time measurements showed that Zn(NO3)2 delayed the setting time by 5 h in comparison to the zinc-less sample. DFT calculations revealed Si(OH)4 to react with [Zn(OH)4]2− via a barrierless transition state, evidencing a kinetic ground for the retardation effect. Additionally, Raman spectroscopy corroborated the DFT results by showing that Q3 species in the proposed mechanism are formed more rapidly in the presence of zinc ions than in its absence.

Effect of zinc ion on synthesis of chromium-containing spinel from wastewater and insight into the synthesis mechanism

Stable spinel can be synthesized in chromium-containing wastewater by ferrite process, which can not only realize the purification of chromium-containing wastewater, but also make chromium resource in the wastewater recycle. However, zinc ion often exists in the chromium-containing wastewater, and easily enters the spinel structure when the wastewater is treated by the ferrite process. Therefore, the effect of zinc ion on the synthesis of chromium-containing spinel from the wastewater was investigated, and the synthesis mechanisms was revealed. The quality of the filtrate, stability and magnetic properties of products synthesized at different initial concentrations of zinc ion were examined, and the results verified that moderate zinc ion enhanced the stability of chromium and magnetic properties of synthetic products, but excessive zinc ion reduced the quality of the filtrate. The synthetic path of products was illustrated by examining the stability and crystal evolution of synthetic product, monitoring the potential and pH, testing the dissolved oxygen, and analyzing the contents of metal ions in the filtrate. The synthesis mechanism was further confirmed by SEM-EDS and mössbauer spectra, and the results demonstrated that the gained solid products were mainly composed of goethite and spinel. It was deduced that the molecular formula of synthetic spinel wasFe3.243+(Fex2+⋅Fe2-x3+⋅Cry3+)O1.5y-0.5x+7.86 in the absence of zinc ion. However, the molecular formula of synthetic spinel was (Zn0.52+⋅Fe2.743+)(Fex2+⋅Fe2-x3+⋅Cry3+)O1.5y-0.5x+7.61 in the presence of zinc ion. The study laid a theoretical foundation for the industrial application of ferrite process in the chromium-containing wastewater.

Zinc(II)‐facilitated nucleophilic addition on N‐(4‐chlorophenyl) carbon hydrazonoyl dicyanide and hybrid complex formation: X‐ray, spectral characteristics, DFT, molecular docking, and biological studies

AbstractThe isolated crystalline, N‐(4‐chlorophenyl) carbonohydrazonoyl dicyanide, NCCD, showed a unique behavior in the presence of zinc ions, ethanol, and H2O. The product was proved to be a two‐unit complex consisting of coordinated zinc(II) complex part, bis‐(1‐(4‐chlorophenyl)‐2‐(1‐cyano‐2‐ethoxy‐2‐iminoethylidene)hydrazin‐1‐ide)zinc(II), Zn (CEIH)2, and a coupled modified organic part, 4‐amino‐N‐(4‐chlorophenyl)‐5‐((4‐chlorophenyl)diazen‐yl)‐6‐ethoxypyrimidine‐2‐carbohydrazonoyl cyanide (ACDPC). Such behavior may be attributed to the activity of nitrile groups in NCCD and the zinc(II) catalytic power in aqueous media. The structures of the products were confirmed by elemental analysis and single‐crystal X‐ray analysis. The spectral properties were analyzed by studying FTIR, UV–Visible, 1H NMR, 13C NMR, and XPS. Moreover, computational calculations including DFT were applied to the synthesized compounds to estimate their optimized structure and deduce some quantum parameters. The FTIR, UV–Visible, and NMR data were compared with the calculated results, showing a good agreement. Molecular docking was applied to study the interaction of NCCD and GNB‐selected protein targets for Escherichia coli (ID: 5I39) and Proteus vagaries (ID: 6QF6). The isolated compounds were investigated as antibacterial, antioxidant, and anticancer agents showing variable activities. The NCCD showed a higher impact as an antimicrobial and anticancer agent, whereas the zinc complex showed better antioxidant behavior using DPPH radical scavenging activity test.

Electrochemical study and experimental simulation of the synergistic effect of a formulation based on Ficus pumila Linn. Leaves extract and zinc sulfate on the XC38 steel corrosion inhibition in NaCl solution

The inhibitive activity of a mixture of Ficus pumila Linn. leaves hydroalcoholic extracts (HEFP) and zinc ions against corrosion of XC38 steel in NaCl solution was investigated. Electrochemical measurements (potentiodynamic polarization and electrochemical impedance spectroscopy at and around the corrosion potential) and surface analysis (SEM/EDX) have shown that the presence of zinc ions considerably increases the inhibitive capacity of HEFP. However, appropriate concentrations of zinc ions (50 and 100 ppm) and of HEFP (200 ppm) are necessary to have an optimal inhibitive effect. The formation of organometallic complexes between zinc ions and some organic compounds of HEFP (polyphenols and carbohydrates) are the determining step of the synergistic inhibition. Since the main inhibitive agents in plant extracts are polyphenols, a simulation of this inhibitive character was electrochemically done with a mixture of flavonoid (quercetin), phenolic acid (gallic acid) and zinc ions in order to elucidate the inhibition mechanism. The obtained results showed that the electrochemical behavior of XC38 steel in the presence of this mixture is quite similar to that obtained in the presence of HEFP + Zn2+ formulation. The proposed inhibition mechanism, which explains the good inhibitive efficiency observed in presence of the HEFP + Zn2+ formulation, is based on concerted reactions between the steel oxidation products (Fe2+ and Fe3+), the zinc ions and the Iron(II) and Iron(III) complexing agents present in the extract.

Unraveling the Gordian knot of insulin resistance in type 2 diabetes mellitus

<abstract> <p>β-cells play an important role in unraveling the Gordian knot of insulin resistance in type 2 diabetes. Firstly, a key feature of the etiology of type 2 diabetes, which appears in the prediabetic phase, is a reduction in the unsaturation index (number of cis carbon-carbon double bonds per 100 acyl chains of membrane phospholipids) compared to healthy controls, which leads to a lower rate of transmembrane glucose transport, and consequently causes reduced glucose effectiveness. Thus, the amount of glucose entering the β-cell via glucose transporter-2 reduces insulin production, leading to reduced insulin sensitivity. Secondly, after synthesis of monomer insulin, six monomer insulin molecules can join together in the presence of zinc ions. The mature hexamers are packed inside mature intracellular vesicles that are transported to the β-cell plasma membrane. Fusion of the intracellular vesicle membrane with the β-cell plasma membrane creates a fusion pore that allows expulsion of monomer insulin molecules into the blood circulation. The large dimensions of the monomer insulin molecule (30 Å wide and 35 Å high) require substantial flexibility of the vesicle membrane and the β-cell plasma membrane. Reduction in the unsaturation indexes leads to a lower rate of insulin transport into the blood circulation, which results in a further decrease in insulin sensitivity.</p> <p>That brings us to a crucial point. The conceit behind the term “insulin resistance” is wrong. It suggests that cells do not respond well to insulin, but the fact is that this term ignores the essential reduction, compared to the plasma glucose concentration, in the amount of glucose entering the β-cell via glucose transporter-2, resulting in reduced insulin production. We now know that an increase in glucose effectiveness, powered by an increased unsaturation index, reframes fundamentally the mechanisms that participate in the glucose homeostasis during type 2 diabetes mellitus.</p> </abstract>

Peptidoglycan recognition protein-S1 (PGRP-S1) from Diaphania pyloalis (Walker) is involved in the agglutination and prophenoloxidase activation pathway.

Recognition of invading foreign exogenous pathogen is the first step to initiate the innate immune response of insects, which accomplished by the pattern recognition receptors (PRRs). Peptidoglycan recognition proteins (PGRPs) serve as an important type of PRRs, which activate immune response by detecting peptidoglycan of microbial cell wall. In this study, we have cloned the full-length cDNA of PGRP gene called PGRP-S1 from the Diaphania pyloalis (Walker). The open reading frame (ORF) of D. pyloalis PGRP-S1 encodes 211 amino acids which containing a secretion signal peptide and a canonical PGRP domain. Multisequence alignment revealed that PGRP-S1 possess the amino acid residues responsible for zinc binding and amidase activity. D. pyloalis PGRP-S1 exhibited the highest transcript level in fat body and followed in head. The mRNA concentration dramatically increased after an injection of Escherichia coli or Micrococcus luteus. Purified recombinant PGRP-S1 exhibit binding ability to peptidoglycans from Staphylococcus aureus or Bacillus subtilis and cause intensive agglutination of E. coli, M. luteus or S. aureus in the presence of zinc ions. Furthermore, phenoloxidase activity significantly increased when the plasma from larvae was incubated with recombinant PGPR-S1 and peptidoglycans from B. subtilis or M. luteus simultaneously. These results implied that PGRP-S1 was a member involving the prophenoloxidase activation pathway. Overall, our results indicated that D. pyloalis PGRP-S1 serve as a PRR to participate in the recognition of foreign pathogen and prophenoloxidase pathway stimulation.

Unraveling the mechanism of tau protein aggregation in presence of zinc ion: The earliest step of tau aggregation

Recent studies have indicated that tau protein aggregation is closely related to Alzheimer's disease. Though the later stages of the aggregation process are extensively studied, it is still unknown how the aggregation occurs in the earliest stage. It is reported that the presence of low micromolar zinc ions can trigger the aggregation process even without the presence of any cofactors like heparin. The earlier studies have indicated that zinc binds to the tau protein in a tetrahedral geometry, binding to two cysteine and two histidine residues. Nevertheless, the mechanism is still unclear on how the aggregation occurs, especially the early events that lead to the aggregation. Here we have used surface-enhanced Raman spectroscopy to study the aggregation process under the presence of zinc ions. We observed a broadening of the C-S stretching band upon the addition of zinc ions, which indicates a direct involvement of the zinc-binding domain in the aggregation process. We attribute that zinc ion promotes the intermolecular bridging of tau monomers through cysteine and histidine binding, and that triggers the aggregation process. Our finding suggests a plausible mechanism of tau protein aggregation under an imbalance of zinc ions inside the pathological brain.

Silymarin Dehydroflavonolignans Chelate Zinc and Partially Inhibit Alcohol Dehydrogenase

Silymarin is known for its hepatoprotective effects. Although there is solid evidence for its protective effects against Amanita phalloides intoxication, only inconclusive data are available for alcoholic liver damage. Since silymarin flavonolignans have metal-chelating activity, we hypothesized that silymarin may influence alcoholic liver damage by inhibiting zinc-containing alcohol dehydrogenase (ADH). Therefore, we tested the zinc-chelating activity of pure silymarin flavonolignans and their effect on yeast and equine ADH. The most active compounds were also tested on bovine glutamate dehydrogenase, an enzyme blocked by zinc ions. Of the six flavonolignans tested, only 2,3-dehydroderivatives (2,3-dehydrosilybin and 2,3-dehydrosilychristin) significantly chelated zinc ions. Their effect on yeast ADH was modest but stronger than that of the clinically used ADH inhibitor fomepizole. In contrast, fomepizole strongly blocked mammalian (equine) ADH. 2,3-Dehydrosilybin at low micromolar concentrations also partially inhibited this enzyme. These results were confirmed by in silico docking of active dehydroflavonolignans with equine ADH. Glutamate dehydrogenase activity was decreased by zinc ions in a concentration-dependent manner, and this inhibition was abolished by a standard zinc chelating agent. In contrast, 2,3-dehydroflavonolignans blocked the enzyme both in the absence and presence of zinc ions. Therefore, 2,3-dehydrosilybin might have a biologically relevant inhibitory effect on ADH and glutamate dehydrogenase.

NMR Studies of the Ion Channel-Forming Human Amyloid-β with Zinc Ion Concentrations.

Alzheimer’s disease (AD) is classified as an amyloid-related disease. Amyloid beta (Aβ) is a transmembrane protein known to play a major role in the pathogenesis of AD. These Aβ proteins can form ion channels or pores in the cell membrane. Studies have elucidated the structure of the transmembrane domain of Aβ ion channels. In addition, various studies have investigated substances that block or inhibit the formation of Aβ ion channels. Zinc ions are considered as potential inhibitors of AD. In this study, we focused on the transmembrane domain and some external domains of the Aβ protein (hAPP-TM), and solution-state NMR was used to confirm the effect on residues of the protein in the presence of zinc ions. In addition, we sought to confirm the structure and orientation of the protein in the presence of the bicelle using solid-state NMR.

Recent Advances in Selected Asymmetric Reactions Promoted by Chiral Catalysts: Cyclopropanations, Friedel–Crafts, Mannich, Michael and Other Zinc-Mediated Processes—An Update

The main purpose of this review article is to present selected asymmetric synthesis reactions in which chemical and stereochemical outcomes are dependent on the use of an appropriate chiral catalyst. Optically pure or enantiomerically enriched products of such transformations may find further applications in various fields. Among an extremely wide variety of asymmetric reactions catalyzed by chiral systems, we are interested in: asymmetric cyclopropanation, Friedel–Crafts reaction, Mannich and Michael reaction, and other stereoselective processes conducted in the presence of zinc ions. This paper describes the achievements of the above-mentioned asymmetric transformations in the last three years. The choice of reactions is related to the research that has been carried out in our laboratory for many years.

Fabrication of Versatile Hollow Metal-Organic Framework Nanoplatforms for Folate-Targeted and Combined Cancer Imaging and Therapy.

Metal-organic frameworks (MOFs) have received extensive attention in the field of biomedicine, particularly serving as multifunctional theranostic nanoplatforms by integrating chemodrugs, imaging agents, and targeting agents. Herein, we report a facile strategy for the fabrication of a hollow and monodisperse MOF (denoted hMIL-88B(Fe)@ZIF-8) consisting of ZIF-8 nanoparticles loaded on the external shell of hollow MIL-88B(Fe). In particular, the hybrid hollow MOF was constructed by partially etching spindlelike MIL-88B(Fe) nanoparticles with 2-methylimidazole in the presence of zinc ions. The obtained hMIL-88B(Fe)@ZIF-8 was then used as a drug/cargo delivery vehicle for loading doxorubicin (DOX), manganese oxide (MnOx) nanoparticles, and folic acid (FA), forming a multifunctional nanoplatform (denoted hM@ZMDF). Importantly, the resulting hM@ZMDF exhibited a specific targeting property for the FA receptor-overexpressed cancer cells (MCF-7 and HepG-2 cells) and then it unloaded DOX and Fe3+ in the tumor microenvironment. Consequently, DOX played dual roles as a chemotherapeutic drug and a fluorescent imaging agent. Also, the released Fe3+ could mediate the Fenton reaction and intracellularly generate toxic hydroxyl radicals in the presence of high glutathione in cancer cells. In addition, MnOx nanoparticles could participate in magnetic resonance imaging. Therefore, the versatile hM@ZMDF nanoplatforms have great potential for smart cancer therapy.