Evaluation of clay-ionene nanocomposite carriers for controlled drug delivery: Synthesis, in vitro drug release, and kinetics

To evaluate the impact of the different structure of quaternary ammonium salts (ionenes) as drug carrier of their corresponding organoclays, new nanocomposite clay-ionene (CI) drug carriers were prepared from montmorillonite (Mt) and polyquaternary ammonium salts (polyionene) and a simple bisquaternary ammonium salt. The CI drug systems were obtained by ion exchange of the sodium Mt (Na + Mt) with at least two-fold excess polyquaternary and bisquaternary ammonium salt compounds by ion exchange between sodium cations of the Na + Mt and the ammonium ions in the polyionene to produce CI systems with free quaternary ammonium halide side chains. Simple di-quaternary ammonium salts were also used to modify Mt. The structures of the prepared CI systems were characterized using Fourier transform-infrared spectroscopy (FT-IR), powder X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). As a model drug, sodium diclofenac (DS) was immobilized onto the CI through the remaining halide ions to provide the CI-diclofenac system (DFS). The release behavior of diclofenac from the different nanocomposites was studied at different pH values. The release behavior of the DFS showed that polyionene systems were slower than the simple bi-quaternary ammonium salts systems were. The kinetics of the release process were described using different models to explain the drug release mechanism.