434279 Short-Time Glassy-like Dynamics Observed in Viscous Protein Solutions with Competing Potential Features

Monday, November 9, 2015
Ballroom F (Salt Palace Convention Center)
Norman J. Wagner, Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE, P. Douglas Godfrin, Chemical and Biomolecular Engineering, University of Delaware, Newark, DE, Yun Liu, Chem & Biomolec. Eng., U Delaware, Newark, DE, Steven D. Hudson, Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD and Lionel Porcar, Large Scale Structures Group, Institut Laue-Langevin, Grenoble, France

Structures in concentrated protein solutions caused by the combination of short-range attraction (SA) and long-range repulsion (LR) have been extensively studied due to their importance in understanding therapeutic protein formulations and the phase behavior in general. Despite extensive studies of kinetically arrested states in colloidal systems with short-range attraction, less is understood for the effect of an additional longer-range repulsion on model colloidal systems with a SA interaction. Highly purified lysozyme is used a model experimental system due to its stable globular structure and SALR interactions at low ionic strength that can be quantitatively modeled. Zero shear viscosity is obtained by microcapillary viscometry to avoid artifacts of interfacial rheological effects. The fluid microstructure and protein short time self diffusion are measured across a broad range of conditions by small angle neutron scattering (SANS) and neutron spin echo (NSE), respectively. Newtonian liquid behavior is observed at all concentrations, even with an increase of zero shear viscosity by almost four orders of magnitude with increasing concentration. However, dynamic measurements demonstrate a sub-diffusive regime at relatively short time scales for concentrated samples at low temperature. The formation of a heterogeneous density distribution is shown to produce localized regions of high density that reduce protein motion, giving it a glassy-like behavior at the short time scale. This heterogeneity occurs at the length scale associated with the intermediate range order driven by the competing potential features that distinguishes this dynamic behavior from commonly studied colloidal gel systems where the whole system is heterogeneous.

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See more of this Session: Poster Session: Fluid Mechanics (Area 1J)
See more of this Group/Topical: Engineering Sciences and Fundamentals