(592f) Construction and Study of Porous Polymer Media for Ion-Exchange Adsorption by Molecular Dynamics

Ion-exchange chromatography employing porous adsorbent particles in which the affinity group/ligand is linked to the base matrix via a polymeric extender, plays a significant role in the separation of biomolecules. In this work, dextran polymer chains are considered as extenders immobilized on an agarose surface and the system is immersed in an aqueous solution. The coarse grain M3B model is appropriately modified in molecular dynamics (MD) simulation studies to represent dextran and agarose and construct the porous adsorption system. We further employ a novel geometrical approach for the surface to impart an additional control variable that can be used to create desirable pore sizes to accommodate ligands and analytes of desirable size. Compatible with the physics of the actual system, this approach covers a substantially larger system than what could be simulated with a simulation box employing a flat surface for the same linear dimensions. The MD modeling and simulations performed in this work provide detailed information about the structure of the porous dextran layers, the distribution of the pore surface area of the porous polymer structure, the distribution of the selected affinity groups/ligands on the surface of the porous polymer structure, as well as the effect of the density of the affinity groups/ligands on the state of the porous polymer structure before the start of the interaction of the analyte with the immobilized ligands. Furthermore, the transport in the pores and the interaction of the molecules of a selected analyte with the immobilized ligands is studied, and these physicochemical mechanisms have a dynamic effect on the pore structure of the dextran layer as well as on the transport and further adsorption of the analyte. Such studies can result in the appropriate selection and design with respect to length and side branching of dextran polymer chains, so that the resulting porous polymer structures are appropriate, after the chosen affinity group/ligand has been immobilized on the surface of the pores, for the effective separation of a biomolecule of interest by ion-exchange adsorption.