Preparation and characterization of an anti-inflammatory agent based on a zinc-layered hydroxide-salicylate nanohybrid and its effect on viability of Vero-3 cells

Determining Structures of Layer-by-Layer Spin-Coated Zinc Dicarboxylate-Based Metal-Organic Thin Films

Thin films of crystalline solids with substantial free volume built from organic chromophores and metal secondary building units (SBUs) are promising for engineering new optoelectronic properties through control of interchromophore coupling. Zn-based SBUs are especially relevant in this case because they avoid quenching the chromophore's luminescence. We find that layer-by-layer spin-coating using Zn acetate dihydrate and benzene-1,4-dicarboxylic acid (H2BDC) and biphenyl-4,4'-dicarboxylic acid (H2BPDC) linkers readily produces crystalline thin films. However, analysis of the grazing-incidence wide-angle X-ray scattering (GIWAXS) data reveals the structures of these films vary significantly with the linker, and with the metal-to-linker molar ratio used for fabrication. Under equimolar conditions, H2BPDC creates a type of structure like that proposed for SURMOF-2, whereas H2BDC generates a different metal-hydroxide-organic framework. Large excess of Zn2+ ions causes the growth of layered zinc hydroxides, irrespective of the linker used. Density functional theory (DFT) calculations provide structural models with minimum total energy that are consistent with the experimentally observed diffractograms. In the broader sense, this work illustrates the importance in this field of careful structure determination, e. g., by utilizing GIWAXS and DFT simulations to determine the structure of the obtained crystalline metal-organic thin films, such that properties can be rationally engineered and explained.

Photocatalytic oxidation of cationic dyes in single and binary solutions in presence of Zn-Cd oxides obtained from calcined LDH

In the present paper, zinc and cadmium layered double hydroxides (ZnCd-LDH) have been prepared through co-precipitation route then calcined at different temperatures. Their photocatalytic activity was determined by photodegradation of industriel toxic dyes (rhodamine B (RB) and crystal violet (CV)) in single and binary solutions illuminated with UVA or sunlight irradiation. It was found that the highest photodiscoloration efficiency was obtained for the nanomaterial heated at 700 °C (ZnCd-700). The physicochemical properties of ZnCd-LDH and ZnCd-700 were determined by PXRD, FTIR, DSC, TG/DTG, and DRS-UV-Vis. By heating the ZnCd-LDH material, some demixtion to ZnO and CdO phases occurred, corresponding to a band gap energy value of 2.93 eV for the formed zinc oxide nanoparticles. The results revealed that with 1 g·L^-1 of ZnCd-700 dose, the photodiscoloration of dyes was enhanced significantly where in single solution, it was > 83.9% and ≥ 98.0% in 90 min of UVA ilumination and sunlight, respectively. Whereas, the removal of CV and RB was > 89.7% and ≥ 98.7% in binary solution under UVA and solar irradiations, respectively. The superoxide anion radical (O₂^•-) was identified as the most influential reactive species for dyes degradation. In binary solution, the CV dye was photodiscolored faster than RB while in single solution, the result was the opposite. The re-use study of ZnCd-700 as photocatalyst showed a slight decrease of dyes discoloration varying between 1.4 and 7.1% from the second to the fourth use.

Layered double hydroxide-based nanocomposite scaffolds in tissue engineering applications

Layered double hydroxides (LDHs), when incorporated into biomaterials, provide a tunable composition, controllable particle size, anion exchange capacity, pH-sensitive solubility, high-drug loading efficiency, efficient gene and drug delivery, controlled release and effective intracellular uptake, natural biodegradability in an acidic medium, and negligible toxicity. In this review, we study potential applications of LDH-based nanocomposite scaffolds for tissue engineering. We address how LDHs provide new solutions for nanostructure stability and enhance in vivo studies' success.

The influence of Ca and Cu additions on the microstructure, mechanical and degradation properties of Zn-Ca-Cu alloys for absorbable wound closure device applications

Novel ternary Zn-Ca-Cu alloys were studied for the development of absorbable wound closure device material due to Ca and Cu's therapeutic values to wound healing. The influence of Ca and Cu on the microstructure, mechanical and degradation properties of Zn were investigated in the as-cast state to establish the fundamental understanding on the Zn-Ca-Cu alloy system. The microstructure of Zn-0.5Ca-0.5Cu, Zn-1.0Ca-0.5Cu, and Zn0.5Ca-1.0Cu is composed of intermetallic phase CaZn13 distributed within the Zn-Cu solid solution. The presence of CaZn13 phase and Cu as solute within the Zn matrix, on the one hand, exhibited a synergistic effect on the grain refinement of Zn, reducing the grain size of pure Zn by 96%; on the other hand, improved the mechanical properties of the ternary alloys through solid solution strengthening, second phase strengthening, and grain refinement. The degradation properties of Zn-Ca-Cu alloys are primarily influenced by the micro-galvanic corrosion between Zn-Cu matrix and CaZn13 phase, where the 0.5% and 1.0% Ca addition increased the corrosion rate of Zn from 11.5 μm/y to 19.8 μm/y and 29.6 μm/y during 4 weeks immersion test.

Enhanced electrochemical performance by nickel-iron layered double hydroxides (LDH) coated on Fe3O4 as a cathode catalyst for single-chamber microbial fuel cells

The improvement of cathode performance has always been the bottleneck and research hot spot for microbial fuel cells (MFCs). An Fe₃O₄@NiFe-LDH composite with a nanoscale core-shell structure containing an Fe₃O₄ magnetic core and a layered double hydroxide (LDH) shell was prepared by the hydrothermal method. The Fe₃O₄@NiFe-LDH was characterized by FT-IR, XRD, SEM and EDS. The characterization results showed that the composite had a unique cauliflower-like nanoflake structure and special pore size distribution, which greatly improved the ORR performance. Moreover, the use of the synthesized Fe₃O₄@NiFe-LDH core-shell structure as an electrode in an MFC was characterized by CV and LSV, which showed that the Fe₃O₄@NiFe-LDH exhibited excellent ORR catalytic properties. The voltage output of the Fe₃O₄@NiFe-LDH MFC was maintained at approximately 0.39 V, with insignificant variations over 110 h. The maximum power density was 211.40 ± 2.27 mW/m², which was 34 times that of the blank control group MFC and was caused by the many electroactive sites, good rate capability and remarkable cycling stability of LDH. This study provides the possibility for using Fe3O4@NiFe-LDH in cathodes to operate continuously and at low cost in fuel cells.

Immobilizing yeast β-glucan on zinc-layered hydroxide nanoparticle improves innate immune response in fish leukocytes

Nanoparticle-based delivery technologies have played a central role in a wide variety of applications, including cell therapy, gene transformation, and cellular delivery of molecular dyes. This work synthesized via ionic exchange a nanoparticle consisting of zinc-layered hydroxychloride coupled with yeast β-glucan (ZG), whose cellular immune response was evaluated using fish spleen leukocytes. Leukocytes from the marine Pacific red snapper (Lutjanus peru) were stimulated with zinc-layered hydroxychloride (ZHC) coupled with yeast β-glucan (GLU) and challenged with live Vibrio parahaemolyticus after 24 h. Structural characterization of this yeast glucan by proton nuclear magnetic resonance (NMR) indicated structures containing (1-6)-branched (1-3)-β-D-glucan. The ZHC and ZG were characterized with X-ray diffraction, infrared spectroscopy, scanning electron microscopy and thermogravimetric analysis. The results of the immunological study showed that ZHC, GLU or ZG were safe for leukocytes because cell viability was higher than 80% compared with DMSO or V. parahaemolyticus exposure. The ZG or GLU treatments enhanced nitric oxide production, superoxide dismutase, catalase and peroxidase activities. Induction of anti- and pro-inflammatory cytokine (IL-1β, IL-6, IL-8, IL-10, IL-12 and IL-17) genes was more pronounced in ZG or GLU treatments compared to the other groups. Based on the results, ZHC nanoparticles can be used as a delivery carrier of yeast β-glucan for enhancing immunity in fish and have great potential application in the aquaculture industry.

Inorganic nanolayers: structure, preparation, and biomedical applications

Hydrotalcite-like compounds are two-dimensional inorganic nanolayers also known as clay minerals or anionic clays or layered double hydroxides/layered hydroxy salts, and have emerged as a single type of material with numerous biomedical applications, such as drug delivery, gene delivery, cosmetics, and biosensing. Inorganic nanolayers are promising materials due to their fascinating properties, such as ease of preparation, ability to intercalate different type of anions (inorganic, organic, biomolecules, and even genes), high thermal stability, delivery of intercalated anions in a sustained manner, high biocompatibility, and easy biodegradation. Inorganic nanolayers have been the focus for researchers over the last decade, resulting in widening application horizons, especially in the field of biomedical science. These nanolayers have been widely applied in drug and gene delivery. They have also been applied in biosensing technology, and most recently in bioimaging science. The suitability of inorganic nanolayers for application in drug delivery, gene delivery, biosensing technology, and bioimaging science makes them ideal materials to be applied for theranostic purposes. In this paper, we review the structure, methods of preparation, and latest advances made by inorganic nanolayers in such biomedical applications as drug delivery, gene delivery, biosensing, and bioimaging.

Development of drug delivery systems based on layered hydroxides for nanomedicine

Layered hydroxides (LHs) have recently fascinated researchers due to their wide application in various fields. These inorganic nanoparticles, with excellent features as nanocarriers in drug delivery systems, have the potential to play an important role in healthcare. Owing to their outstanding ion-exchange capacity, many organic pharmaceutical drugs have been intercalated into the interlayer galleries of LHs and, consequently, novel nanodrugs or smart drugs may revolutionize in the treatment of diseases. Layered hydroxides, as green nanoreservoirs with sustained drug release and cell targeting properties hold great promise of improving health and prolonging life.