Hybrid Hierarchical Porous Silica Templated in Nanoemulsions for Drug Release

A new nanocarrier for loading and releasing drugs is reported, and ketoprofen was used as a model drug. More precisely, the carrier is a hybrid material prepared by combining oil-in-water (O/W) nanoemulsions, into which the drug has been solubilized, with mesostructured silica. This organic-inorganic hybrid material shows a controlled release of the drug that is pH dependent. If the drug is impregnated into the bare hierarchical meso-/macroporous dual silica material, obtained after the removal of the organic components by extraction, only 8 wt.-% of ketoprofen is released in a phosphate buffer medium (pH 7.4), probably owing to its low solubility in the aqueous phase. The drug solubility and release are increased strongly by the addition of Pluronic micelles to the receptor phase; this suggests a micelle-promoted and -assisted release mechanism. Whatever the vehicle, the release profiles of ketoprofen always follow the Korsmeyer-Peppas model with a diffusional release exponent value lower than 0.5, characteristic of a pseudo-Fickian release mechanism. Moreover, the release of ketoprofen is better controlled from the hybrid nanocarrier than from the hierarchical bare porous silica.