L-DOPA stabilization on sol-gel silica to be used as neurological nanoreservoirs: Structural and spectroscopic studies

The paper reports on the stabilization of L-DOPA into a nanostructured silica matrix prepared by the sol-gel method in addition the characterization of the resultant materials. For this purpose, the L-DOPA/SiO2 and SiO2 materials were synthesized from the hydrolysis and condensation of tetraethoxysilane and the addition of the drug during this stage. It was necessary to use a nitrogen flow in order to obtain an inert atmosphere to avoid drug oxidation. The resulting materials were characterized using both by nuclear magnetic resonance and infrared spectroscopies. However, X-ray diffraction, N2 adsorption-desorption and thermogravimetric analyses were also used. An “in vitro” drug release test was performed using water as a release medium. The spectroscopic results show the successful drug stabilization within the silica network without undergoing oxidation. The resultant materials were mesoporous with amorphous nature and L-DOPA was thermally stable at 250 °C. The experimental drug release data adjusted to the theoretical equations show that the release mechanism is governed by a diffusion of the drug through silica mesopores.