Presentation: 2025 ND EPSCoR Annual conference 

October 21, 2025, NDSU Memorial Union, Fargo, North Dakota

Protonation Effect of Amino Acids on Their Interactions with Ferromagnetic Montmorillonite Nano-Clay (MMT)

The interaction of amino acids with the surface of modified clay minerals have attracted a great amount of interest due to their promising properties for electro chemical, biomedical and pharmacological applications. Using spin-polarized density functional theory (DFT), we study the changes in the magnetic properties of Fe and Mg co-doped montmorillonite (MMT) nanoclay introduced by interactions with several amino acids (histidine, isoleucine, and lysine) and 3,3’- diaminobenzidine molecule in their protonated and deprotonated forms. Our calculations show that positively charged amino acids via protonation of their amino groups bind more strongly to the clay surface than their neutral counterparts. This increase in the interaction with the nanoclay causes notable redistribution of charge density from the clay surface to the molecule and a reduction in the total magnetic dipole moment. However, similar to the neutral cases, the magnetic properties of the nanoclay are sensitive to the type of molecule, its configuration on the nano-clay surface and the solvent conditions its under. The predicted tunability of magnetic properties may permit magnetic separation, visualization, and cell imaging and may also have a therapeutic benefit of these materials. Thus, our calculations predict that the molecule-MMT interactions can be probed by electro-magnetic techniques, which extends experimental tools for studying these materials for bio-applications