Evaluation of SiO2 Sonogels, Prepared by a New Catalyst-Free Method, as Drug Delivery System

Recently, we reported on the synthesis of catalyst-free SiO2 sonogels prepared by the sonication of a neutral distilled water/ tetraethyl ortosilicate mixture. The purpose of the present study was to evaluate the feasibility of using these sonogels as pharmaceutical delivery systems. A certified color additive (sunset yellow, SY) was used as a model compound for the release experiments. Different amounts of dye were incorporated into the gels before drying. Sonogels were characterized by scanning electron microscopy and differential scanning calorimetry. The effect of three drying temperatures (25°C, 40°C and 80°C) and two mean grain sizes (1125 and 630 μm) on release behavior was analyzed. The analysis of variance showed no significant differences between the Higuchi's constants (KH) obtained for SY-loaded sonogels dried at 80°C with different SY loads, irrespective of the mean grain size. In contrast, for SY-loaded sonogels dried at 40°C, differences were found between sonogels loaded with 2.7, 7.7, 12....