Wed April 3rd 2024
16:00 – 17:00
Seminar Separation by Polyelectrolyte Complexation
Saskia Lindhoud


Cellular processes are extremely efficient, the most complex reactions occur in the blink of an eye. This efficiency can be only be achieved by spatiotemporal control of components. To achieve this the cellular fluids contain dynamic droplet-like compartments called membrane-less organelles or biomolecular condensates. Our work is inspired by this spatiotemporal organisation of components, because if we understand how this works we can develop selective aqueous based extraction media.
Many membrane-less organelles consist of cationic intrinsically disordered proteins and (anionic) RNA, therefore these structures strongly resemble polyelectrolyte complexes. We use polyelectrolyte complexes as model systems for these cellular condensates and study the partitioning of molecules and proteins between the dilute aqueous phase and the dense phase.
In this colloquium I will first discuss the basics of polyelectrolyte complexation and complex coacervation. Then I will show that it is possible to use polyelectrolyte complexes to concentrate and separate proteins and, extract small molecules. The uptake of molecules strongly depends on the ionic strength, complex composition, pH, temperature, etc., so we are dealing with an enormous phase space.
To understand why proteins can be separated using polyelectrolyte complexes, we had to take a step back. Currently we are developing an NMR based methodology to determine how all components, i.e., the oppositely charged polyelectrolytes and their accompanying counterions are distributed after complex formation. Access to these data will help us to better understand polyelectrolyte complexation and develop separation materials based on polyelectrolyte complexes, e.g., extraction media, porous and dense membranes. In addition our data are needed to improve theoretical models for polyelectrolyte complexation.
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