Modulating the Partitioning of Microparticles in a Polyethylene Glycol (PEG)-Dextran (DEX) Aqueous Biphasic System by Surface Modification

Aqueous two-phase systems (ATPSs) or aqueous biphasic systems are useful for biological separation/preparation and cell micropatterning. Specifically, aqueous two-phase systems (ATPSs) are not harmful to cells or biomaterials; therefore, they have been used to partition and isolate these materials from others. In this study, we suggest chemically modifying the surface of target materials (micro/nanoparticles, for example) with polymers, such as polyethylene glycol and dextran, which are the same polymer solutes as those in the ATPS. As a simple model, we chemically coated polyethylene glycol or dextran to the surface of polystyrene magnetic particles and observed selective partitioning of the surface modified particles to the phase in which the same polymer solutes are dominant. This approach follows the principle "like dissolves like" and can be expanded to other aqueous biphasic or multiphasic systems while consuming fewer chemicals than the conventional modulation of hydrophobicities of solute polymers to control partitioning in aqueous biphasic or multiphasic systems.