Phosphorus as a promoter of a nickel catalyst to obtain 1-phenylethanol from chemoselective hydrogenation of acetophenone.

Two catalysts were prepared using monodisperse pre-synthetized nanoparticles of metallic nickel and nickel phosphides with the same average diameter. Both nanoparticles species were deposited on the same support: mesoporous silica nano-spheres of MCM-41. This support is suitable to inhibit agglomeration and sintering processes during preparation steps. Therefore, two supported and activated catalysts with the same average nanoparticles diameter were obtained. They differ only in the nature of the active species: metallic nickel and nickel phosphides. The effect of the presence of a second element (phosphorus), more electronegative than nickel, on the activity and selectivity in the chemoselective hydrogenation of acetophenone was studied. The reaction conditions were: H2 pressure of 1 MPa, 80 °C using n-heptane as solvent. With the aim to understand the catalytic results, nanoparticles, support and catalysts were carefully characterized by X-ray diffraction, diffuse light scattering, transmission electron microcopy, high resolution transmission electron microcopy, selected area electron diffraction, scanning electron microcopy, Fourier transformer infrared spectroscopy, N2 adsorption at -196 °C, atomic absorption, H2 and CO chemisorption and volumetric oxidation. Considering these results and geometric and electronic characteristics of the surface of both active species, a change in the adsorption intermediate state of acetophenone in presence of phosphorus is proposed to explain the hydrogenation chemoselectivity of nickel phospides.

Preparation and characterization of a supported system of Ni2P/Ni12P5 nanoparticles and their use as the active phase in chemoselective hydrogenation of acetophenone.

Ni2P/Ni12P5 nanoparticles were obtained by thermal decomposition of nickel organometallic salt at low temperature. The use of different characterization techniques allowed us to determine that this process produced a mixture of two nickel phosphide phases: Ni2P and Ni12P5. These nickel phosphides nanoparticles, supported on mesoporous silica, showed activity and high selectivity for producing the hydrogenation of the acetophenone carbonyl group to obtain 1-phenylethanol. This is a first report that demonstrates the ability of supported Ni2P/Ni12P5 nanoparticles to produce the chemoselective hydrogenation of acetophenone. We attribute these special catalytic properties to the particular geometry of the Ni-P sites on the surface of the nanoparticles. This is an interesting result because the nickel phosphides have a wide composition range (from Ni3P to NiP3), with different crystallographic structures, therefore we think that different phases could be active and selective to hydrogenate many important molecules with more than one functional group.

Binding and encapsulation of doxorubicin on smart pectin hydrogels for oral delivery.

Pectins (Pec) of 33 to 74 % esterification degree were tested with doxorubicin (Dox), a very high toxic drug widely used in cancer therapies. Pec with 35 and 55 % DE were selected because of the Dox binding higher than Pec microspheres of 35 and 55 % obtained by ionotropic gelation with Ca⁺² have 88 and 66 % Dox loading capacity. Kinetic Dox release showed more than 80.0 and about 30.0 % free drug from 35 % and 55 % Pec formulations at pH 7.4, and 37 °C after 1-h incubation, respectively. Besides, Dox release decrease to 12 % in 55 % Pec microsphere formulation after 1-year storage at 4 °C. FTIR analysis of Pec-Dox complex showed hipsochromic shifts for the σ(C=O), δ(N-H) and σ(C-C) vibrational modes compared to Dox spectrum suggesting strong interaction between the drug cargo and the matrix. Rheological studies of Pec and Pec-Dox samples flow behavior exhibited a shear-thinning nature. Fifty-five percent of Pec showed higher viscosity than the viscosity for 35 % Pec in all range of temperatures analyzed, and decreased when the temperature is raised. Besides, Pec-Dox complexes have higher viscosity values than those of the corresponding Pec samples, and viscosity curves as function of shear rate for 35 % Pec-Dox are above the curves of 55 % Pec-Dox. In both cases, the results are confirming significant interaction between the cargo and the matrix, which also was established in viscoelastic dynamic analysis.

Studies of ciprofloxacin encapsulation on alginate/pectin matrixes and its relationship with biodisponibility.

Screening of ciprofloxacin (Cip) with selected biopolymers brings about 90% antibiotic interactions with a coacervate composed of alginate/high metoxylated pectin in 2:1 ratio. Fourier transform infrared spectroscopy analysis provides information about the nature of this interaction, revealing ionic and hydrophobic patterns among the molecules. Alginate/high methoxylated pectin gel microspheres developed by ionic gelation encapsulates 46.8 ± 5.0% Cip. The gel matrix can release Cip in a sustained manner, releasing 42.7 ± 0.2% in 2 h under simulated stomach pH conditions, and 83.3 ± 1.1% Cip release in 80 mM phosphate at pH = 7.40 (intestinal). The increase of sodium chloride from 50 to 200 mM implies a Cip release from 69.0 ± 1.5% to 95.1 ± 3.6% respectively in 2 h. Scanning electron microscopy revealed the cohesive effect of HM pectin over alginate molecules on the microsphere surface. Those results guarantee all Cip contained in the alginate/HM pectin microspheres could be released in an established kinetic profile along the gastrointestinal tract, avoiding the Cip undesirable side effects during absorption.

The Risk-based Treatment of Acute Pulmonary Embolism.

UNLABELLED: Risk evaluation and prognostic stratification based upon clinical and radiological findings and new cardiac biomarkers, such as natriuretic peptides (NP) and troponins, represent key points in modern management of acute pulmonary embolism (PE). Literature evidence shows that normotensive PE with right heart dysfunction (RHD), defined as submassive PE, has poorer prognosis when compared to normotensive PE without RHD, defined as non-massive PE; thus whether submassive PE should be managed more aggressively and with closer monitoring represents the crucial question about acute PE treatment. Although the answer is yet unclear, the most recent guidelines address to thrombolysis as treatment choice in selected high risk patients with submassive PE. Guidelines also clarify the indications for unfractioned and low molecular weight heparins and fondaparinux. Therefore, in the present article, the authors focus on modern risk-based therapeutic guidelines of acute PE. KEYWORDS: Pulmonary embolism; Treatment; Prognosis; Biomarkers; Chocardiography; Hemodynamic; Guidelines.

Highly anisotropic distribution of iron nanoparticles within MCM-41 Mesoporous Silica.

Electron microscopy techniques are used to visualize the spatial distribution of iron nanoparticles inside a mesoporous MCM-41 molecular sieve. Direct observation of the iron oxide nanoparticles by STEM-HAADF imaging reveals a highly non-uniform spatial distribution inside the mesopores. These particles are retained in the pores after a reduction treatment unlike the behavior found in other similar systems. It is found that thermal treatments induce changes in its morphology, creating nanowires from particle strings.