Ibuprofen loading into mesostructured silica using liquid carbon dioxide as a solvent

Abstract

It has been demonstrated that the pharmaceutical molecule, Ibuprofen, can be loaded into mesoporous silica using liquid (near-critical) carbon dioxide as the solvent, and that the resulting material had a high Ibuprofen content (300 mg Ibuprofen/g SiO₂). A high enrichment (300 times) of Ibuprofen in the pores was observed in comparison to the Ibuprofen concentration in the solution. When similar experiments were performed in CO₂ (l) mixed with minor amounts (5 mol-%) of other organic cosolvents (cyclohexane, acetone or methanol), a significantly lower loading capacity of Ibuprofen into the mesoporous material was achieved. The drug-loaded mesoporous silica material was analyzed with Thermogravimetric Analysis (TGA), confocal Raman microscopy, X-ray Powder Diffraction (XRPD) and Scanning Electron Microscopy (SEM). It was found that the Ibuprofen loaded into the mesoporous silica host was amorphous and that Ibuprofen was present both at the surface and in the centre of the mesoporous silica particles. Furthermore, the SEM images did not reveal any large flakes of Ibuprofen molecules outside the mesoporous silica particles.