Adsorption of tamoxifen on montmorillonite surface

The anticancerous drug tamoxifen is becoming a promising therapy, although some administration handicaps should be improved. Montmorillonite is a natural phyllosilicate and its use as carrier of the tamoxifen can be an interesting alternative for drug delivery system. Syntheses at different pH of montmorillonite-tamoxifen hybrids have shown promising possibilities. However, it is necessary to know the driving forces and intermolecular interactions responsible for tamoxifen adsorption on montmorillonite at different pH. Atomistic calculations of these systems have been applied based on empirical interatomic potentials. Theoretical simulations were used to explain the stoichiometry of the tamoxifen intercalation into the montmorillonite to understand the experimental behavior. The results showed there is influence on the clay structure when there is pH adjustment, with varying particle size, as well as variability in drug intercalation. Cationic species of tamoxifen was adsorbed by cation exchange mechanism and an additional adsorption of molecule as tamoxifen citrate pair also contributed in the interaction, being more energetically favorable. [Display omitted] •Atomistic calculations to simulate adsorption of tamoxifen citrate together with the montmorillonite excipient.•Tamoxifen adsorption on montmorillonite occurs in the interlamellar space.•The mechanism of cation exchange with tamoxifen cations and the interaction of the tamoxifen citrate ionic pair.•The increase in pH favors the entry of the tamoxifen citrate ionic pair.•Major adsorption interactions involve hydrogen bonding and electrostatic interactions.