Simultaneous purification and refolding of proteins by affinity precipitation and macro (affinity ligand)-facilitated three phase partitioning (MLFTPP)

Partitioning-dependent conversion of polyelectrolyte assemblies in an aqueous two-phase system

Partitioning refers to the distribution of solute molecules in the two immiscible phases of a mixture of two solutions, such as an aqueous two-phase system (ATPS). The partitioning of RNA and peptide has been adjusted in situ to facilitate their assembly into intracellular membraneless organelles. Despite the immense potential of this approach in artificial systems, a partitioning-dependent assembly of macromolecules has been limited, due to the sophisticated processing associated with their in situ modification. Here we demonstrate an approach to direct the assembly of polyelectrolytes in an ATPS through varying their partitioning via pH changes. Microcapsules can be converted to microgel particles as the polyelectrolytes selectively partition to different emulsion phases when changing pH. Such partitioning-dependence can also be equally applied for complexing hydrophilic nanoparticles with polyelectrolytes in an ATPS. By enabling access of hydrophilic materials across the aqueous interface freely, the ATPS allows modification of their intrinsic properties in situ; this advantage will inspire more versatile control over the partitioning of hydrophilic materials and will create new multi-functional biomaterials.

Affinity Partitioning-Induced Self-Assembly in Aqueous Two-Phase Systems: Templating for Polyelectrolyte Microcapsules

Affinity partitioning refers to the preferential dissolution of solute molecules in a particular liquid phase of an immiscible liquid-liquid mixture, such as an aqueous two-phase system (ATPS). Affinity partitioning in ATPS is widely used to achieve extraction and purification of biomolecules. However, the potential of applying it to direct the self-assembly of solutes into controlled structures has been largely overlooked. Here we introduce the affinity partitioning of polyelectrolytes in ATPS to induce their self-assembly into polyelectrolyte microcapsules. The approach is purely based on the preferential solubility of different polyelectrolytes in different aqueous phases; therefore it has wide applicability and exhibits excellent compatibility with bioactives. The release of encapsulated components can be triggered by changing the pH value or ionic strength of the surrounding environment. The proposed method represents an important advance in fabricating multifunctional materials and inspires new ways to engineer sophisticated structures with hydrophilic macromolecules.