Collaborative Research: Molecular Basis for Protein Sorption in Polymer-modified Chromatographic Media

We propose to characterize quantitatively the functional properties of polymer-derivatized adsorbents for preparative ion-exchange chromatography (IEC) of proteins, and to infer from associated fundamental experimental and modeling studies the mechanisms of protein sorption and transport in these materials. Within the larger universe of adsorbents for industrial-scale IEC separations of proteins, polymer-derivatized media (PDM) have emerged as a class of materials with especially attractive adsorption and transport properties that can significantly enhance operating efficiency over conventional media to keep pace with recent strides in cell culture technology. Such adsorbents are used operationally much like conventional media but differ from them in allowing for three-dimensional (volumetric) partitioning rather than two-dimensional surface sorption. There are consequently various similarities and differences in behavior that have not all been explained mechanistically in terms of the known structural features of the respective media. Therefore while it is possible to seek optimal conditions and media using existing products, the possibility of further improvements, in use of novel designs, materials or operating strategies, cannot be assessed thoroughly without a clearer fundamental understanding of the basis for the favorable properties of PDM in general. In particular, microstructural and microfunctional data that can yield mechanistically-based structure-function relationships are lacking. We will address this deficiency via a multiscale investigation organized around three specific aims: Aim 1: Determine comparative sorption and transport characteristics for proteins on polymer-derivatized media with different architectures. Aim 2: Measure microscopic characteristics of the sorption and desorption processes and the sorbed state as a guide to identification and analysis of sorption and transport mechanisms. Aim 3: Generalize and apply molecular theories to describe the sorption equilibrium and kinetics of proteins in polymer-derivatized media.