Molecular vibrational analysis and MAS-NMR spectroscopy study of epilepsy drugs encapsulated in TiO2-sol-gel reservoirs.
A nanostructured matrix, consisting of titania, was designed in such a way that an antiepileptic drug could be encapsulated and released according to a well-defined time release schedule. The titania was synthesized by a sol-gel method in which titanium n-butoxide was used as the precursor for the formation of the sol. The synthesis was optimized to yield a homogeneous particle size with a high porosity and an anatase crystal structure. The antiepilectic drugs, phenytoine or valproic acid, were added during the gelation stage in order to obtain a homogeneous gel phase. The resulting nanostructured matrix including the drug showed only weak attractive forces, such as London forces, dipole-dipole coupling, and in some cases hydrogen bonds. The resulting assembly, referred to as a reservoir, was characterized using conventional FTIR and NMR spectroscopic techniques. Theoretical simulation studies were performed so as to obtain an understanding of the equilibrium electrostatic potential distribution and the relative charges on the titania and the anticonvulsants.