In vitro controlled release of antihypertensive drugs intercalated into unmodified SBA-15 and MgO modified SBA-15 matrices.

The use of nanotechnology in medicine and more specifically in drug delivery systems is set to spread rapidly. In order to broaden the range of matrices and implicitly to develop the class of drug delivery systems based on diffusion mechanism, in this study the starting materials, SBA-15 powder matrices, were engineered by MgO modification for antihypertensive drugs intercalation. Captopril and aliskiren were used as drug models. All powders, unmodified and MgO-modified silica matrices, and their corresponding drug-loaded samples were characterized by X-ray diffraction, N(2) adsorption and desorption, FTIR spectroscopy and scanning electron microscopy. The studied drug carriers were tested in the controlled drug release process and the influence of the silica pore morphology and geometry on drug release profiles was extensively studied. In order to analyze the data obtained from the in vitro release studies and to evaluate the kinetic release mechanism, the Korsmeyer and Peppas equation was used. The obtained drug delivery system based on MgO-SBA-15 matrix exhibits exciting structural features and is therefore promising for its use as antihypertensive drug delivery system, having potential therapeutic benefits resulting in safe and effective management of captopril and aliskiren adsorption and in vitro release.

Direct spectroscopic detection of framework-incorporated vanadium in mesoporous silica materials.

Framework-incorporated vanadium mesoporous silica materials with different contents in vanadium were obtained by a facile, direct synthesis at room temperature, using VOSO4 x 5H2O as the vanadium precursor. The porous characteristics of the samples and the coordination environment of the vanadia in the structure were studied by a combination of techniques: X-ray diffraction, N2-adsorption/desorption, FT-Raman, FTIR-PAS and UV-Vis-DR, electron paramagnetic resonance (EPR) and electron nuclear double resonance (ENDOR) spectroscopy. A structural comparison is made using pulsed EPR and ENDOR spectroscopic techniques between vanadia deposited on the surface of MCM-41 by the Molecular Designed Dispersion method and as-synthesised samples of vanadia incorporated in the mesoporous silica framework using the above-mentioned synthesis method. The EPR study on the non-calcined samples proves the incorporation of a high amount of vanadium in the silica framework by the observation of a strong hyperfine coupling of the unpaired electron with 29Si. It demonstrates the feasibility for EPR to reveal structural information on true incorporation of metal ions in framework positions leading to metal oxides.