فهرست مطالب elham boorboor azimi

Ordered nanoporous silica such as SBA-15 has a great potential for application in controlled drug release systems. Chemical modification of the silanol groups of SBA-15 allows better control over drug loading and release. Therefore, tris(2-aminoethyl) amine-functionalized mesoporous silica SBA-15 was evaluated as a potential carrier for the delivery of citalopram.

Tris (2-aminoethyl) amine-functionalized SBA-15 was synthesized and characterized by various methods. Citalopram was loaded on the functionalized SBA-15 and drug release into simulated body fluid (SBF) solution and phosphate buffers was investigated.

The optimal condition for loading of the citalopram was obtained at pH = 9 after stirring for 5 minutes. The release profile of citalopram was monitored in phosphate buffers with three different pH values of 5, 7, and 8. A faster release rate at lower pH value was observed, suggesting a weaker interaction because of the protonation of the amino group of the functionalized SBA15. The average release rate of citalopram from each gram of functionalized SBA-15 was 12 µg h-1 in the SBF.

The results showed that loading amount and release rate of citalopram depended on pH value and the release process showed a very slow release pattern. Therefore, tris (2-aminoethyl) amine-functionalized SBA-15 is a suitable carrier for controlled release of citalopram and has a great potential for disease therapy.

Tris(3-bromo-acetylacetonato) chromium(III) as an inert and very stable complex with a good leaving group was synthesized using as-prepared Cr(acetylacetonate)3. Highly ordered nanoporous silica (LUS-1), with some great features, was functionalized with 3-aminopropyltriethoxysilane. Then the as-prepared product was modified with tris(3-bromo-acetylacetonato) chromium(III) under mild reaction condition. Results obtained from N2 adsorption desorption, and X-ray powder diffraction proved the successful anchoring of the Cr(III) complex inside the pores of LUS-1 without any distortion in the structure. The morphology and configuration of LUS-1 with Scanning electron microscope and Transmission electron microscopy and Energy-dispersive X-ray spectrum of the product were prepared. Mid and Far Infrared spectroscopy confirmed that the product was possibly an amine, formed by substitution addition of NH2 group on LUS-1, to C-Br in acac ligands and not a weak and non-stable Schiff base. Thermal stability of the species was assessed by thermogravimetric analysis. This novel method resulted in the formation of a stable covalently bonded acetylacetonate to the support that it can be used in acidic media or even in polar solvents without altering the structure.