Soft-templating synthesis of mesoporous alumina enriched with lanthana and its potential as diclofenac delivery system

This work reports the soft-templating synthesis of Al2O3/La2O3, its physicochemical and structural characterization, and application as diclofenac (DFC) delivery system. The porous and chemical structure of the prepared sample were examined by N2 adsorption, scanning and transmission electron microscopy as well as infrared spectroscopy. The soft-templating synthesis enabled the formation of a mesoporous structure of alumina enriched with lanthana, having a well-developed surface area approaching 156 m2/g, average pore size of 10.3 nm, and average pore volume of 0.32 cm3/g. TEM images revealed the presence of an ordered structure of Al2O3/La2O3 consisting of hexagonal mesopores in the material. Based on X-Ray fluorescence spectrometry analysis, the effectiveness of lanthana incorporation to alumina structure was confirmed. The designed material was tested as a potential diclofenac delivery system with a maximum sorption capacity of 82 mg/g. Equilibrium and kinetic evaluations suggested that DFC sorption onto Al2O3/La2O3 is quite complex and may occur due to hydrogen bonding and electrostatic interactions. The impact of pH on the sorption process was significant - DFC sorption was favorable in an acidic environment. The release tests of the DFC adsorbed on the surface of Al2O3/La2O3 were carried out to determine the stability of their interactions. System was analyzed at pH 7.2 and 1.2, reaching 50% and nearly 80% of DFC release, respectively, which suggest possible application of designed material as a new carrier for the sustained release of different active pharmaceutical ingredients.