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Luminescent Behavior of Zn Halide Derivatives of 4-Phenyldinaphtho2,1-d:1′,2′-f1,3,2dioxaphosphepine 4-Oxide and Single-Crystal X-ray Structure Determination of the Ligand
The two enantiomers of chiral phosphonate 4-phenyldinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepine 4-oxide, O=PPh(BINOL), were synthesized from the proper 1,1′-bi-2-naphtol (BINOL) enantiomer and characterized. The structure of the (S)-enantiomer was elucidated by means of single-crystal X-ray diffraction. The reaction with anhydrous ZnBr[sub.2] afforded complexes having the general formula [ZnBr[sub.2]O=PPh(BINOL)[sub.2]] that showed intense fluorescence centered in the near-UV region rationalized on the basis of TD-DFT calculations. The corresponding Mn(II) complexes with the general formula [MnX[sub.2]O=PPh(BINOL)[sub.2]] (X = Cl, Br) exhibited dual emission upon excitation with UV light, with the relative intensity of the bands dependent upon the choice of the halide. The highest energy transition is comparable with that of the Zn(II) complex, while the lowest energy emission falls in the red region of the spectrum and is characterized by lifetimes in the hundreds of microseconds range. Although the emission at lower energy can also be achieved by direct excitation of the metal center, the luminescence decay curves suggest that the band in the red range is possibly derived from BINOL-centered excited states populated by intersystem crossing.
Journal Article
Effect of zinc on liver cirrhosis with hyperammonemia: A preliminary randomized, placebo-controlled double-blind trial
To our knowledge, no randomized study has shown whether zinc replacement therapy is effective for hyperammonemia in liver cirrhosis; therefore, we performed a double-blind, placebo-controlled trial to examine efficacy and safety of the zinc replacement therapy.
Patients with liver cirrhosis and hyperammonemia (at or above the institutional reference value) and hypozincemia (≤65 μg/dL) were enrolled in the outpatient units of the participating institutions and were randomly divided to receive placebo (P group) or zinc acetate preparation at a dose of 3 capsules/d for a total zinc content of 150 mg/d (Z group) by the envelope method. Of the 18 enrolled patients, 6 dropped out; thus, the analyses included 12 patients (5 in the P group and 7 in the Z group). Variations in blood concentrations of zinc and ammonia as well as liver function test results were compared.
Blood zinc levels significantly increased in the Z group (P = 0.0037; Friedman test) but not the P group. Blood ammonia levels significantly decreased in the Z group (P = 0.0114; Friedman test) but not the P group. The percent change in blood ammonia level also revealed significant reduction at the eighth week in the Z group (P = 0.0188: Mann-Whitney test). No serious adverse events attributable to the zinc preparation were noted.
Although this study is preliminary and includes a small sample, it is, to our knowledge, the first randomized controlled trial to show that zinc supplementation for 3 mo seems effective and safe for treating hyperammonemia in liver cirrhosis. Studies with a larger sample size are needed to confirm our findings.
Journal Article
Polar and Non-Polar Znsub.1−xMgsub.xO:Sb Grown by MBE
The article presents a systematic study of Sb-doped Zn[sub.1−x]Mg[sub.x]O layers, with various concentrations of Mg, that were successfully grown by plasma-assisted MBE on polar a- and c-oriented and non-polar r-oriented sapphire substrates. X-ray diffraction confirmed the polar c-orientation of alloys grown on c-and a-oriented sapphire and non-polar structures grown on r-oriented substrates. A uniform depth distribution of the Sb dopant at level of 2 × 10[sup.20] cm[sup.−3] was determined by SIMS measurements. Raman spectroscopy revealed the presence of Sb-related modes in all samples. It also showed that Mg alloying reduces the compressive strain associated with Sb doping in ZnO. XPS analysis indicates that the chemical state of Sb atoms in ZnMgO is 3+, suggesting a substitutional position of Sb[sub.Zn], probably associated with two V[sub.Zn] vacancies. Luminescence and transmission spectra were measured to determine the band gaps of the Zn[sub.1−x]Mg[sub.x]O layers. The band gap energies extracted from the transmittance measurements differ slightly for the a, c, and r substrate orientations, and the differences increase with increasing Mg content, despite identical growth conditions. The differences between the energy gaps, determined from transmission and PL peaks, are closely correlated with the Stokes shift and increase with the Mg content in the analyzed series of ZnMgO layers.
Journal Article
Oral Zinc Supplementation Reduces the Erythropoietin Responsiveness Index in Patients on Hemodialysis
Background: In hemodialysis (HD) patients, zinc depletion caused by inadequate intake, malabsorption, and removal by HD treatment leads to erythropoiesis-stimulating agent (ESA) hyporesponsiveness. This study investigated the effects of zinc supplementation in HD patients with zinc deficiency on changes in the erythropoietin responsiveness index (ERI). Methods: Patients on HD with low serum zinc levels (<65 μg/dL) were randomly assigned to two groups: The polaprezinc group (who received daily polaprezinc, containing 34 mg/day of zinc) (n = 35) and the control group (no supplementation) (n = 35) for 12 months. All the 70 patients had been taking epoetin alpha as treatment for renal anemia. ERI was measured with the following equation: Weekly ESA dose (units)/dry weight (kg)/hemoglobin (g/dL). Results: There were no significant changes in hemoglobin levels within groups or between the control and polaprezinc groups during the study period. Although reticulocyte counts were increased immediately after zinc supplementation, this change was transient. Serum zinc levels were significantly increased and serum copper levels were significantly decreased in the polaprezinc group after three months; this persisted throughout the study period. Although there was no significant change in the serum iron or transferrin saturation levels in the polaprezinc group during the study period, serum ferritin levels significantly decreased following polaprezinc treatment. Further, in the polaprezinc group, ESA dosage and ERI were significantly decreased at 10 months and nine months, respectively, as compared with the baseline value. Multiple stepwise regression analysis revealed that the change in the serum zinc level was an independent predictor of lowered ERI. Conclusions: Zinc supplementation reduces ERI in patients undergoing HD and may be a novel therapeutic strategy for patients with renal anemia and low serum zinc levels.
Journal Article
Zinc as a Gatekeeper of Immune Function
After the discovery of zinc deficiency in the 1960s, it soon became clear that zinc is essential for the function of the immune system. Zinc ions are involved in regulating intracellular signaling pathways in innate and adaptive immune cells. Zinc homeostasis is largely controlled via the expression and action of zinc “importers” (ZIP 1–14), zinc “exporters” (ZnT 1–10), and zinc-binding proteins. Anti-inflammatory and anti-oxidant properties of zinc have long been documented, however, underlying mechanisms are still not entirely clear. Here, we report molecular mechanisms underlying the development of a pro-inflammatory phenotype during zinc deficiency. Furthermore, we describe links between altered zinc homeostasis and disease development. Consequently, the benefits of zinc supplementation for a malfunctioning immune system become clear. This article will focus on underlying mechanisms responsible for the regulation of cellular signaling by alterations in zinc homeostasis. Effects of fast zinc flux, intermediate “zinc waves”, and late homeostatic zinc signals will be discriminated. Description of zinc homeostasis-related effects on the activation of key signaling molecules, as well as on epigenetic modifications, are included to emphasize the role of zinc as a gatekeeper of immune function.
Journal Article
Biogenic Zinc nanoparticles: green approach to synthesis, characterization, and antimicrobial applications
Background
Biogenic synthesis of zinc nanoparticles (ZnNPs) has attracted significant interest due to their unique properties and potential biological applications. Unlike chemical and physical methods, biogenic synthesis offers a greener and more eco-friendly alternative. This study explores the synthesis of zinc-based nanoparticles using two distinct bacterial strains.
Results
In this study, zinc nanoparticles were synthesized in two forms: single-phase zinc sulfide nanoparticles (ZnS NPs) and mixed-phase zinc sulfide-oxide nanoparticles (ZnS-ZnO NPs), using
Achromobacter
sp. S4 and
Pseudomonas
sp. S6. The synthesis conditions were optimized for each strain, with pH playing a crucial role:
Achromobacter
sp. S4 favored basic conditions (pH 8.0) for zinc nanoparticles production, while
Pseudomonas
sp. S6 preferred acidic conditions (pH 4.7). TEM analysis revealed that Zn NPs from
Pseudomonas
sp. S6 were rod-shaped, whereas those from
Achromobacter
sp. S4 were spherical. Further characterization using EDX, XRD, and FTIR confirmed the successful synthesis of single phase ZnS NPs and hybride phase ZnS-ZnO NPs. Antimicrobial dose-response testing showed that single-phase ZnS NPs inhibited
Klebsiella pneumoniae
, while mixed-phase ZnS-ZnO NPs were effective against
Staphylococcus epidermidis
at 100 µg/ml based on inhibition zone measurements.Furthermore, the mixed-phase ZnS-ZnO NPs at 25 µg/ml demonstrated superior inhibition of microbial growth in sludge samples, likely due to a synergistic effect.
Conclusion
The study demonstrates the successful biogenic synthesis of ZnS NPs, and ZnS-ZnO NPs using two bacterial strains, with distinct morphological and functional properties. The use of two bacterial species was to assess strain-specific differences in nanoparticle synthesis and performance. The synthesized nanoparticles exhibited promising antimicrobial and environmental remediation potential, highlighting their applicability in both biomedical and environmental fields.
Journal Article
Fate of Zinc Oxide Nanoparticles Coated onto Macronutrient Fertilizers in an Alkaline Calcareous Soil
Zinc oxide (ZnO) nanoparticles may provide a more soluble and plant available source of Zn in Zn fertilizers due to their greater reactivity compared to equivalent micron- or millimetre-sized (bulk) particles. However, the effect of soil on solubility, spatial distribution and speciation of ZnO nanoparticles has not yet been investigated. In this study, we examined the diffusion and solid phase speciation of Zn in an alkaline calcareous soil following application of nanoparticulate and bulk ZnO coated fertilizer products (monoammonium phosphate (MAP) and urea) using laboratory-based x-ray techniques and synchrotron-based μ-x-ray fluorescence (μ-XRF) mapping and absorption fine structure spectroscopy (μ-XAFS). Mapping of the soil-fertilizer reaction zones revealed that most of the applied Zn for all treatments remained on the coated fertilizer granule or close to the point of application after five weeks of incubation in soil. Zinc precipitated mainly as scholzite (CaZn2(PO4)2.2H2O) and zinc ammonium phosphate (Zn(NH4)PO4) species at the surface of MAP granules. These reactions reduced dissolution and diffusion of Zn from the MAP granules. Although Zn remained as zincite (ZnO) at the surface of urea granules, limited diffusion of Zn from ZnO-coated urea granules was also observed for both bulk and nanoparticulate ZnO treatments. This might be due to either the high pH of urea granules, which reduced solubility of Zn, or aggregation (due to high ionic strength) of released ZnO nanoparticles around the granule/point of application. The relative proportion of Zn(OH)2 and ZnCO3 species increased for all Zn treatments with increasing distance from coated MAP and urea granules in the calcareous soil. When coated on macronutrient fertilizers, Zn from ZnO nanoparticles (without surface modifiers) was not more mobile or diffusible compared to bulk forms of ZnO. The results also suggest that risk associated with the presence of ZnO NPs in calcareous soils would be the same as bulk sources of ZnO.
Journal Article