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

Chang Byun,Daehee Kim,Minkyung Kim

doi:10.3390/coatings8030085

Abstract

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.

Highlights

The surface of micro/nanoparticles dramatically affects their physical and chemical properties [1].The partitioning of micro/nanoparticles for separation and analysis has been studied for various purposes such as improving sensitivity and efficiency for material collection [2] and sensing methods [1,3].For example, partitioning has been applied to actuate interactions of a model bacterial system via the magnetic movement of bacterial microcolonies
Dextran was chemically conjugated to the surface of polystyrene (PS)-coated microparticles so that the attachment of dextran onto the particle surface might increase the positive interaction or affinity of the microparticle to the lower layer of a polyethylene glycol (PEG)-dextran (DEX) aqueous biphasic system, which is usually called the “like dissolves like” rule
Bovine serum albumin (BSA, heat shock fraction, protease free, pH 7, >98%), methoxy polyethylene glycol amine (molecular weight (MW): 10,000), and amino-dextran were each purchased from Sigma-Aldrich

Summary

Introduction

The surface of micro/nanoparticles dramatically affects their physical and chemical properties [1].The partitioning of micro/nanoparticles for separation and analysis has been studied for various purposes such as improving sensitivity and efficiency for material collection [2] and sensing methods [1,3].For example, partitioning has been applied to actuate interactions of a model bacterial system via the magnetic movement of bacterial microcolonies. The introduction of an aqueous biphasic system with dextran-conjugated microparticles enabled successful partitioning E. coli into sub-microliter droplets [4]. This method could two-dimensionally locate target colonies in a biological interaction study for the first time, the fundamental mechanisms underlying the phenomenon were not fully investigated or explained in detail within a short period of time. Dextran was chemically conjugated to the surface of polystyrene (PS)-coated microparticles so that the attachment of dextran onto the particle surface might increase the positive interaction or affinity of the microparticle to the lower layer of a polyethylene glycol (PEG)-dextran (DEX) aqueous biphasic system, which is usually called the “like dissolves like” rule. There was a possibility that the reason the PS particles moved to the lower DEX-rich layer was not mainly the affinity increase of the DEX-conjugated particles but the increase in mass due to the surface attachment of the DEX-polymer to the particle

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