Microscopic dynamic properties of antibody solutions

Connecting to macroscopic phase behaviour and pharmaceutical applicability

Many chemicals and polymers relies on the production of ethene and propene that exceeded 200 million tons in 2015, mostly produced by steam cracking of light paraffins. The separation of ethene and propene from other hydrocarbons is actually carried out by the cryogenic distillation. The high energy demand of this technology makes desirable the development of new processes, being the zeolites based separation the most promising. This alternative route takes advantage of the molecular sieving properties of zeolites and the possibility of tuning their polarity. One approach to adjust the polar character of silicoaluminate zeolites is by the presence of cations in the voids channels and cavities.

Here, we propose to study the interaction of alkenes (ethene and propene) adsorbed on Ag-zeolites with different Si/Al ratio and silver loading. We will follow a multidisciplinary approach combining INS spectroscopy with theoretical calculations, solid state nuclear magnetic resonance (NMR) and X-ray absorption (XAS) studies for understanding the mechanism of alkene-zeolite interaction in cation containing zeolites. The information will be of high interest for developing new processes decreasing the energy consumption in the actual separation processes, which is of great industrial interest what has motivated the collaboration of CEPSA in the project. Antibody protein injections are used in various therapies.

The conflicting requirements of minimizing the injection volumes and of limited injectable viscosities motivate pharmaceutical research on dense aqueous antibody solutions. The macroscopic phase behavior in protein solutions may depend on minute changes of, for instance, the temperature in a physiologically relevant range. We will combine small-angle x-ray and neutron scattering, high-resolution neutron spectroscopy as well as x-ray photon correlation spectroscopy to obtain a dynamic picture on the molecular level of antibody solutions, systematically addressing the phase behavior comprising monomeric solution states, cluster formation, as well as gel- and glass-like arrested states depending on external parameters such as temperature or additives.

The protein and cluster center-of-mass diffusion and the internal relaxations on the molecular level will be measured simultaneously. The results will be interpreted with models and simulations from colloid physics. We expect to better understand (1)the link between microscopic interactions and phase behavior relevant for pharmaceutical applicability, as well as, more fundamentally, the link between macroscopic viscosity and diffusion on nanosecond time scales; and (2) the biological, pharmacological and medical function and specificity of antibodies.