Regensburg 2016 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 10: Colloids and Complex Fluids III (Joint Session CPP/DY/BP)
BP 10.6: Vortrag
Montag, 7. März 2016, 16:15–16:30, H42
Kinetics of liquid-liquid phase transition in protein solutions exhibiting LCST phase behavior studied by USAXS — •Fajun Zhang1, Stefano Da Vela1, Michal Braun1, Michael Sztucki2, and Frank Schreiber1 — 1Institut für Angewandte Physik, Universität Tübingen, 72076 Tübingen — 2ESRF, Grenoble, France
We present the results of the early stage kinetics of liquid-liquid phase separation (LLPS) in protein-salt solutions studied by ultra-small angle x-ray scattering (USAXS). The model system of bovine serum albumin (BSA) with YCl3 [1,2] shows LLPS and a lower critical solution temperature (LCST) phase behavior and can be rationalized using an ion-activated patchy-colloid model [3]. We focus on the phase transition of the dense liquid phases after a T-jump aiming at the arrested or slowed down kinetics. The USAXS curves of sample solutions after a T-jump exhibit a peak that grows in intensity and shifts to lower q values with time. The characteristic length (ξ) obtained from this scattering peak increases with time approximately as t0.3. The interface between the dilute and dense phase is quickly established as a Porod region (q−4) is visible within a few seconds. Thus the kinetics of the intermediate stage of phase transition was followed by USAXS. It is interesting to see that ξ(t) is nearly independent on the jump temperatures (below 40 ∘C). At a higher temperature jump (45 ∘C), a slowed down kinetics was observed indicating that the gelation line was approached. [1] F. Zhang, et al. Phys. Rev. Lett. 101, 148101 (2008) Proteins 78, 3450 (2010). [2] F. Zhang, et al. Soft Matter 8, 1313 (2012). [3] F. Roosen-Runge, et al. Sci. Rep. 4, 7016 (2014).