Dresden 2017 – wissenschaftliches Programm
CPP 47.2: Vortrag
Mittwoch, 22. März 2017, 16:45–17:00, ZEU 255
The role of aggregates in the stabilization of protein foams — •Manuela E. Richert and Björn Braunschweig — Institut für Physikalische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstraße 28/30, 48149 Münster, Germany
Native and fluorescein isothiocyanate (FITC) labelled bovine serum albumin (BSA) were used to investigate the role of protein aggregates in the stabilization of aqueous protein foams through structure-property relations that reach from the molecular to the macroscopic scale. Protein modified air/water interfaces, which are ubiquitous in aqueous foam, were studied with tensiometry and vibrational sum-frequency generation (SFG). At the air/water interface, SFG and tensiometry provide information on coverage and the net charging state of the interface and thus information on the isoelectric point (IEP) of labelled and native BSA proteins at the air/water interface is gained. At the interfacial IEP a reversal of the phase of OH stretching bands from interfacial H2O molecules is observed in SFG spectra and corresponds to a minimum in the surface tension. The latter can be attributed to the formation of protein aggregates at the interface which promotes macroscopic foam stability. Using confocal fluorescence microscopy aggregates of labelled proteins are found to be predominantly located inside foam lamella where they possibly form a gel-like network and thus cause non-DLVO like interactions.