Folic acid-layered double hydroxides hybrids in skin formulations: Technological, photochemical and in vitro cytotoxicity on human keratinocytes and fibroblasts

Abstract Folic acid (FA) is a key factor in the physiological processes of cell metabolism; as it is involved in DNA synthesis and repair, it can be used in the treatment of aged and photo-damaged skin. The main drawbacks associated to FA use, particularly for topical applications, are the limited solubility and the sensitivity to UV rays. Hybrids of FA with two kinds of layered double hydroxides (ZnAl-LDH and MgAl-LDH) were prepared and characterized showing suitable particle size, flow properties and UV photoprotection. The introduction of FA-LDHs in the external water phase of O/W emulgels produced an enhancement of their flow properties; moreover, the spectrophotometric analyses showed that very good photostability is maintained even after their introduction into the formulations. In-vitro release studies showed that the FA-LDH containing emulgels promoted a sustained FA release as expected. Finally, the safety of FA-LDH was evaluated by in-vitro studies performed on human keratinocytes (HaCaT) and human primary dermal fibroblasts (as a skin representative). The obtained results showed a high cytotoxic effect of ZnAl-LDH-FA in both cell lines

Study of Different H2/CO2 Ratios as Feed in Fischer-Tropsch Reactor with Iron-Based Nano-Hydrotalcite Catalysts

CO2-FTS is among the most viable methods for converting CO2 into useful chemicals and fuels in order to minimize CO2 emissions. Due to its chemical inertness, however, effective conversion continues to be a difficulty. The challenges in terms of yield and mechanism have attracted the interest of different research groups in the development of a new carbon dioxide hydrogenation catalysts, capable of reaching satisfactory results. In this work, a selection of nano ternary hydrotalcites (HTlc) were synthesized with and without ultrasound in order to develop active Fe-based catalysts for the Fischer–Tropsch synthesis. HTlc consists mostly of metal hydroxides in which different metal atoms are uniformly distributed at the atomic level. The reaction was carried in a lab scale plant in a fixed bed configuration. All fresh and used catalysts were examined and characterized using XRPD, ICP-OES, SEM, TEM, BET. Ternary HTlc composed of Mg, Cu, and Fe was synthesized using an ultrasound-assisted co-precipitation technique (MCF-US). HTlc was tested for carbon dioxide hydrogenation reaction with a study concerning different H2/CO2 ratios in order to evaluate the product distribution as well as the efficiency of the catalyst itself. The CO2 conversion resulted higher and more stable in feeds with higher H2 quantities. The selectivity towards higher chain hydrocarbons was higher for lower H2/CO2 ratios whereas methane and carbon monoxide selectivities were adequately low

Recent developments in intercalation compounds: chemistry and applications

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Oxidative Stability of Long-Chain Fatty Acids with Different Unsaturation Degrees into Layered Double Hydroxides

Nowadays, there is increasing evidence that the intake of essential fatty acids (FAs) and oleic acid has high nutritional importance. However, the vulnerability of these FAs to oxidation deserves special attention. FA oxidation may be avoided or delayed by intercalation of its anionic form in inorganic matrices as layered double hydroxides (LDH). Thus, the aim of the study was to evaluate the protective effects of MgAl LDH towards oleate (O), linoleate (L) and α-linolenate (Ln) degradation. The incorporation and the loading of different FAs in anionic form in LDH was determined by X-ray diffraction and thermogravimetric analysis (TGA), respectively. In order to study the selectivity of LDH towards the FA, the inorganic solid was equilibrated with a mixture of O, L and Ln (1:1:1). TGA and gas chromatography showed that Ln was preferentially intercalated. Free FA (FFA) and intercalated FA (IFA) were heated at 40 °C in the dark and then analyzed weekly for a maximum of 42 days. Their oxidative stability was evaluated by monitoring the primary and secondary oxidative compounds. The volatile compounds were determined by solid-phase microextraction, coupled with gas chromatography–mass spectrometry. Peroxide values were higher in FFA samples than in IFA samples, such as hexanal and trans,trans-2,4-heptadienal % contents. The results showed the potential of LDH intercalation for FA preservation from oxidative modification

Effect of the Synthesis Route and Fe Presence on the Redox Activity of Ni in Layered Double Hydroxides

Pt electrodes coated with a Ni/Al or Ni/Fe layered double hydroxide (LDH) were studied to investigate whether the presence of Fe and the extent of crystallinity affect the performance of the Ni centers as redox mediators for oxidizable compounds. The LDHs were synthesized by both a chemical and an electrochemical method, which allowed the obtainment of thin and well-adherent LDH films having similar morphology but a different crystallinity degree. Fe centers were not electroactive but they influenced the electroactivity of Ni, shifting the redox potential to less anodic values and increasing the percentage of the electroactive Ni sites. The LDHs prepared by electrodeposition were more conductive than the chemically synthesized LDHs, and, when Fe was the trivalent metal, the electronic conductivity was further increased. The highest electrocatalytic efficiency, evaluated taking glucose as model compound, was obtained for the electrodes coated with the electrochemically synthesized LDHs

Immobilized Palladium Nanoparticles on Zirconium Carboxy-Aminophosphonates Nanosheets as an Efficient Recoverable Heterogeneous Catalyst for Suzuki–Miyaura and Heck Coupling

Zirconium phosphate glycine diphosphonate nanosheets (ZPGly) have been used as support for the preparation of solid palladium nanoparticles, namely Pd@ZPGly. Thanks to the presence of carboxy-aminophosponate groups on the layer surface, ZPGly-based materials were able to stabilize a high amount of palladium (up to 22 wt %) also minimizing the amount of metal leached in the final products of representative important cross-coupling processes selected for proving the catalysts’ efficiency. The catalytic systems have been fully characterized and used in low amounts (0.1 mol %) in the Suzuki–Miyaura and Heck cross-couplings. Moreover, the protocols were optimized for the use of recoverable azeotropic mixtures (aq. EtOH 96% or aq. CH3CN 84%, respectively) and in the flow procedure allowing one to isolate the final pure products, without any purification step, with very low residual palladium content and with a very low waste production