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Journal of Chemistry
Volume 2013, Article ID 267464, 11 pages
http://dx.doi.org/10.1155/2013/267464
Research Article

Calorimetric Study of Mesoporous SBA-15 Modified for Controlled Valproic Acid Delivery

1Departamento de Química, Facultad de Ciencias, Universidad Nacional de Colombia, Bogotá, Colombia
2Departamento de Química, Facultad de Ciencias, Grupo de Investigación en Sólidos Porosos y Calorimetría, Universidad de los Andes, Bogotá, Colombia

Received 4 July 2012; Revised 7 October 2012; Accepted 7 October 2012

Academic Editor: Jose Alberto Pereira

Copyright © 2013 Liliana Giraldo and Juan Carlos Moreno-Piraján. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

SBA-15 ordered mesoporous silica functionalized with (3-aminopropyl)triethoxysilane (APTES) was used as the carrier for anticonvulsant drug 2-propylpentanoic acid (valproic acid). The surface of SBA-15 containing free silanol groups was modified with 3-aminopropyltriethoxysilane via postsynthetic reaction. Functionalization of the carrier with basic aminopropyl groups resulted in an ionic interaction with acidic valproic acid. The samples of carriers and carrier-drug complexes were characterized by elemental analysis, N2 adsorption, FTIR, and UV spectroscopy. The adsorption of valproic acid on modified mesoporous matrix was proportional to the amount of introduced aminopropyl groups. A thermodynamic study with isothermal titration calorimetry (ITC) was made to characterize the modification and encapsulation of SBA-15 with APTES and valproic acid, respectively. The maximum content of deposited drug in modified SBA-15 was close to 30 wt.%. Tests performed in acidic solution (pH 2.0) showed the best pharmaceutical availability.