Effect of surface functionalization of silica aerogel on their adsorptive and release properties

Due to their high surface area, open pore structure and biocompatibility silica aerogels were shown to be a promising candidate for drug delivery systems. This work aims to show the possibility of functionalizing silica aerogel with functional groups to tailor their surface properties for specific applications. Amino groups were taken as a model functional group. Ketoprofen loading on aerogels was taken as a drug delivery application. Two different functionalization approaches were followed: pretreatment of the gel before the drying step, and a post treatment of the dried aerogels. The amino-functionalized aerogels obtained by both methods were characterized by CHN and BET analysis, as well as UV-spectroscopy. It has been shown that the functionalized silica aerogels obtained by these methods maintain similar structural properties as the original ones. For the first time transparent amino-modified aerogels with a surface area up to 1000 m(2)/g were obtained. These aerogels were loaded with the drug ketoprofen by adsorption from supercritical CO(2). The loading was shown to be a function of the concentration of the amino groups on the aerogel surface, due to their strong adsorptive interactions with the acidic group of ketoprofen. The release rate of ketoprofen from the loaded amino-modified aerogels was close to that of original ones. Thus, aerogels functionalization opens the possibility to design a high capacity carrier for a specific active substance, as well as to control the release of that substance in the corresponding media. (C) 2010 Elsevier B.V. All rights reserved.