Primary Research Areas

Research in the Lenhoff group is focused on two primary areas: Protein Chromatography, and Protein Solution Thermodynamics and Phase Behavior

Protein Chromatography

Protein separation processes are crucial to protein production, with chromatography being the workhorse of most separation and purification processes. Confocal images of protein uptake on chromatography media.Process models accounting for transport effects (convection, diffusion) as well as kinetics and thermodynamics can serve as the basis for scale-up, but the models require each of the constituent phenomena to be understood and described quantitatively; this is the focus of our efforts. We are seeking in particular to relate key properties of proteins, e.g., adsorption equilibria, to their molecular structures. Coupled to this is the role of separations media, where we are, for instance, examining the effect of the chemical structure and the pore structure of chromatographic packings on AKTA chromatography system.chromatographic performance (transport and equilibrium). The experimental tools that we use provide insights at levels ranging from macroscopic to molecular; we use column liquid chromatography, batch uptake measurements, scanning confocal microscopy, electron microscopy and colloid science tools such as scanning probe microscopy (SPM). Similarly, our theoretical work is performed at different levels: we seek predictions of adsorption equilibria from molecular-level computations, and of column performance from traditional and novel transport and adsorption models.

Students working in this area are Jim Angelo, Rahul Bhambure, and Stijn Koshari.

Protein Thermodynamics and Phase Behavior

Protein separations processes such as crystallization and precipitation, as well as drug formulation, food processing and other areas of bioengineering depend on the properties of proteins in solution as well as their phase behavior. We are seeking to understand these phenomena mechanistically in terms of the molecular structures of the proteins involved. Microscopic lysozyme crystalsAgain we do so via experimental and theoretical work at various levels. Our experimental work includes measurements of protein interactions, generally in terms of osmotic virial coefficients, using scattering methods and self-interaction chromatography, as well as measurements of phase behavior. The dense phases may include crystals, gels, precipitates and concentrated solutions, and we are exploring both their formation and its relation to the interaction measurements as well as relevant applications. These approaches are being applied to both soluble proteins and membrane proteins. Associated theoretical and computational work is aimed at explaining trends in the virial coefficient results and simulating actual phase behavior. For this purpose we use molecular biophysical methods, accounting in particular for specific biological interactions and interactions in which the modulating role of water is critical.

Students working in this area are Anvar Samadzoda, Amit Vaish, and Dan Greene.