Structure and surface chemistry in crystalline mesoporous (CeO(2-δ))-YSZ

Mesoporous metal oxides (CeO(2-δ))-YSZ have been synthesized by a versatile direct synthesis method using ionic cetyltrimethylammonium bromide (CTAB) and different nonionic (block copolymers) as surfactants and urea as hydrolyzing agent. The synthesis was realized at pH=9 using tetraethylammonium hydroxide (TEAOH) as pH mediator. Calcination at 550 °C led to the formation of crystalline metal oxides with uniform mesoporosity. The obtained materials have been characterized by thermogravimetric analysis (TG-DTG), wide and small-angle X-ray diffraction (XRD), Raman spectroscopy, Brunauer, Emmett and Teller (BET) surface area analysis, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). All the obtained materials exhibits mesoporous structure, crystalline structure indexed in a cubic symmetry, showing a high surface area, a uniform and narrow pore size distribution, spherical morphology typical for the mesoporous materials. The crystalline and mesoporous structures, surface chemistry and stoichiometry for the samples synthesized using ionic and nonionic surfactants have been discussed.     

Matrix-dependent cooperativity in spin crossover Fe(pyrazine)Pt(CN)4 nanoparticles

Anisotropic nanoparticles of the Fe(pyrazine)Pt(CN)(4) network were prepared embedded in various matrices that revealed to have a dramatic effect on the cooperative spin crossover phenomena. By a judicious choice of the nature of the matrix and the control of interparticle distances, a hysteresis of 15 K was achieved close to room temperature for such nano-objects.     

Resveratrol in Solid Lipid Nanoparticles

This article investigates the possibility of producing solid lipid nanoparticles (SLN) as protective vehicle of resveratrol, an antioxidant characterized by a fast trans-cis isomerization. SLN aqueous dispersions were produced by hot melt homogenization technique and characterized. It was found that the presence of tetradecyl-γ-cyclodextrin in SLN formulation induced an improvement of nanoparticle characteristics. Moreover, a significant reduction in resveratrol photodegradation was noted when the molecule was entrapped in SLN which became more pronounced in the presence of tetradecyl-γ-cyclodextrin. A notable in vitro porcine skin accumulation and an increased antioxidative efficacy were observed by entrapping resveratrol in nanoparticles.     

Lipid Nanosystems in Topical PUVA Therapy

8-Methoxsalen was vehicled in nanoemulsion and in solid lipid nanoparticles (SLN) prepared by the hot homogenization technique in order to be used in topical psoralen UVA (PUVA) therapy. Drug entrapment efficiency in nanoparticles was improved by choosing the appropriate lipid matrix. The use of α-tocopherol in the lipid phase reduces 8-methoxsalen induced photooxidation of porcine skin, which was evaluated in vitro by a malondialdehyde (MDA) test: This result is promising to reduce in vivo human skin irritation after PUVA therapy, which can be attributed to skin photooxidation.     

Application Relevant Characterization of Aqueous Silica Nanodispersions

This work describes the application relevant characterization of eight commercially available silica powders dependent on dispersing procedure using different instruments: photon correlation spectroscopy, nitrogen adsorption, and particle charge detector. The particle size of silica was found to be different in dispersion from that of all types of fumed silica, where, after proper dispersion, the measured average particle size is similar and much higher than the primary particle size. The different properties of these two silica types will be discussed.     

Steric and Electronic Effects on the Configurational Stability of Residual Chiral Phosphorus‐Centered Three‐Bladed Propellers: Tris‐aryl Phosphanes

A series of tris‐aryl phosphanes, structurally designed to exist as residual enantiomers or diastereoisomers, bearing substituents differing in size and electronic properties on the aryl rings, were synthesized and characterized. Their electronic properties were evaluated on the basis of their electrochemical oxidation potential determined by voltammetry. The configurational stability of residual phosphanes, evaluated by dynamic HPLC on a chiral stationary phase or/and by dynamic ¹H and ³¹P NMR spectroscopy, was found to be rather modest (barriers of about 18–20 kcal mol^?1), much lower than that shown by the corresponding phosphane oxides (barriers of about 25–29 kcal mol^?1). For the first time, the residual antipodes of a tris‐aryl phosphane were isolated in enantiopure state and the absolute configuration assigned to them by single‐crystal anomalous X‐ray diffraction analysis. In this case, the racemization barrier could be calculated also by CD signal decay kinetics. A detailed computational investigation was carried out to clarify the helix reversal mechanism. Calculations indicated that the low configurational stability of tris‐aryl phosphanes can be attributed to an unexpectedly easy phosphorus pyramidal inversion which, depending upon the substituents present on the blades, can occur even on the most stable of the four conformers constituting a single residual stereoisomer.     

Direct In Situ Determination of Ascorbic Acid in Fruits by Screen‐Printed Carbon Electrodes Modified with Nylon‐6 Nanofibers

A simple sensing unit based on a disposable screen printed carbon electrode coated by an electrospun nylon‐6 nanofibrous membrane was developed for in situ selective determination of ascorbic acid (AA) in different types of fruits. The membrane, prepared by electrospinning, represents a selective barrier to possible interferents, such as phenolic compounds, allowing an improved selectivity towards AA. No sample preparation and/or dilution is necessary since the new device is applied directly “pricking” the fruit with the electrode. A good correlation was obtained between the amperometric in situ method and a reference chromatographic methodology (HPLC‐UV) when applied to various fruit samples.     

Systematic investigation and in vitro biocompatibility studies on mesoporous europium doped hydroxyapatite

This paper reports the systematic investigation of europium doped hydroxyapatite (Eu:HAp). A set of complementary techniques, namely Fourier Transform Infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and the Brunauer-Emmett-Teller (BET) technique were used towards attaining a detailed understanding of Eu:HAp. The XPS analysis confirmed the substitution of Ca ions by Eu ions in the Eu:HAp samples. Secondly, Eu:HAp and pure HAp present type IV isotherms with a hysteresis loop at a relative pressure (P/P₀) between 0.4 and 1.0, indicating the presence of mesopores. Finally, the in vitro biological effects of Eu:HAp nanoparticles were evaluated by focusing on the F-actin filament pattern and heat shock proteins (Hsp) expression in HEK293 human kidney cell line. Fluorescence microscopy studies of the actin protein revealed no changes of the immunolabelling profile in the renal cells cultured in the presence of Eu:HAp nanoparticles. Hsp60, Hsp70 and Hsp90 expressions measured by Western blot analysis were not affected after 24 and 48 hours exposure. Taken together, these results confirmed the lack of toxicity and the biocompatibility of the Eu:HAp nanoparticles. Consequently, the possibility of using these nanoparticles for medical purposes without affecting the renal function can be envisaged.