Regensburg 2016 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 26: Poster: Charged Soft Matter, Polyelectrolytes, Ionic Liquids

CPP 26.5: Poster

Dienstag, 8. März 2016, 18:15–21:00, Poster B2

Cluster formation in protein solutions with trivalent salts investigated by light scattering — •Michal Braun, Olga Matsarskaia, Daniel Soraruf, Fajun Zhang, and Frank Schreiber — Institut für Angewandte Physik, Universität Tübingen, 72076 Tübingen

The formation of clusters or small aggregates in protein solutions with (partly) attractive interactions is considered an unsolved issue. Salt ions offer a way to manipulate the interaction with a high degree of control. In a variety of protein-(multivalent) salt systems reentrant condensation has been found. For a fixed protein concentration the solution is clear below a salt concentration c^*, then becomes turbid (so-called regime II) and redissolves again above c^**. Aggregates, possible precursors of crystallization, and their diffusion behavior were recently studied in a system that phase separates macroscopically between c^* and c^**. The diffusion behavior there points to c^* being a spinodal line which can be deduced from the fact the collective diffusion coefficient D becomes zero at c^* [1]. Here a light scattering study of a system is presented where there is no macroscopic phase separation at room temperature, only slight turbidity in regime II. D also decreases steeply towards a c^* where it attains its minimum value but remains finite. In regime II D stays constant and then starts to increase again slowly.

[1] Soraruf et al., Soft Matter, 10, 894, 2014