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Open Chemistry
|
2012
|
vol. 10
|
issue 5
1688-1695
EN
Mesoporous alumina has many environmental applications as catalysts support and adsorption or separation material. We studied the synthesis conditions for the mesoporous alumina formation from aluminum isopropoxide in the presence of anionic (lauric and stearic acid), cationic (cetyltrimethylammonium bromide, CTAB) and non-ionic (triblock poly(ethylene oxide)-poly(propylene oxide)-polyethyleneoxide, P123) templates. The X-ray diffraction data show that the alumina mesophases obtained at 550°C in the presence of fatty acids or P123 have amorphous walls, whereas the samples prepared at 500°C by using CTAB, in alkaline medium are crystalline with a γ-alumina structure. The solvothermal treatment caused the alumina mesophase with crystalline walls to be obtained at 550°C. The samples were investigated by nitrogen adsorption-desorption isotherms and scanning electron microscopy. The obtained alumina mesophases have specific surface areas in the range of 300–450 m2 g−1, narrow pore size distribution, and different morphology depending on the template used in the synthesis. [...]
EN
A light-responsive material, aminoazobenzene functionalized AlMCM-41, was synthesized and characterized in order to be used as carrier for drug delivery devices. The light-induced hydrophobic-hydrophilic switching effect of azobenzene functionalized aluminosilicate was exploited in the release of irinotecan, a cytostatic drug. To obtain the functionalized mesoporous support, an azobenzene-silane precursor was synthesized by coupling 4-(4′-aminophenylazo) benzoic acid with 3-aminopropyl triethoxysilane and further grafted on AlMCM-41. The azobenzene functionalized mesoporous aluminosilicate exhibited no significant toxicity towards murine fibroblast healthy cells and a reduced toxicity towards murine melanocyte cells. The hybrid materials obtained by loading irinotecan on AlMCM-41 (wt. 35.4%) and aminoazobenzene modified AlMCM-41 (wt. 22%), respectively were characterized by FTIR, small and wide angle XRD, N2 adsorption-desorption isotherms and DSC analyses. A two-fold increase in the drug release rate from azobenzene functionalized aluminosilicate in phosphate buffer solution under UV irradiation was noticed, as compared with dark conditions. Moreover, the azobenzene functionalization of AlMCM-41 significantly increased the irinotecan delivery rate and total cumulative release in comparison with the pristine AlMCM-41 in similar conditions.
3
76%
EN
Three mesostructured silica-type carriers, MCM-41 and MCM-41 functionalized by a postsynthesis grafting procedure with hydrophilic aminopropyl groups (MCM-APTES) and hydrophobic vinyl moieties (MCM-VTES), respectively, were investigated in order to elaborate drug delivery systems (DDS) for irinotecan molecules. All studied drug delivery systems exhibited higher cytotoxicity on murine embrionary fibroblastic (MEF) cells than free irinotecan at the same content of the cytostatic agent, whereas no toxicity was observed for the three unloaded carriers. The cytotoxic effect of irinotecan loaded on MCM-41-type carriers continued to increase even 24 h after ceasing the cell exposure to the drug and remained significantly higher than that of free irinotecan. The cellular uptake of silica-type hybrids was investigated by labelling MCM-APTES with Rhodamine B. In the case of the studied DDS, an endocytotic mechanism was found to be involved in the cell uptake process, and it was used to explain the cytotoxicity differences between free irinotecan and drug loaded on MCM-41-type supports.
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