Applications of complex coacervation now include enzyme immobilization, protein purification, protein drug delivery, and phase manipulation in food science and personal care products, all of which involve colloid-polyelectrolyte (PE) interactions. But precipitation (L-S separation), detrimental in all these applications, often appears to accompany (L-L) coacervation. Precipitation might be considered a natural consequence of enhanced inter-macroionic forces, in which PE-colloid ion-pairing replaces counterion-macroion pairing and the expulsion of those counterions leads to desolvation. However, it is unclear if coacervate literally transforms to precipitate, or if the two processes are concurrent. Motivated in part by the coacervation/precipitation overlap for protein-polysaccharide systems, we turn to surfactant micelles as protein surrogates because of their more isotropic shape and charge distribution. More importantly, the exquisite temperature dependence of the PE-micelle system leads to greater differentiation of L-L and L-S phase boundaries, and thence to methods for manipulating them.

Exploring the coacervation/precipitation interface

253rd National Meeting (2017)

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