Selective partitioning of (Biomacro)molecules in the crowded environment of double-hydrophilic block copolymers

The phase separation in aqueous solutions of a double-hydrophilic block copolymer (DHBC) at concentrations mimicking the crowded environment in cells and its performance as a potential protein purification system are investigated. Similar to processes of self-coacervation, the coexistence of aqueous polymer-rich and polymer-depleted microscopic phases is observed and the partitioning of various species in them is investigated. Whereas small molecules, poly(ethylene glycol), and dextran can moderately partition in both phases, proteins and DNA are strongly enriched in the polymer-depleted phase, offering a pathway for biomacromolecule purification. While aqueous two-phase systems based on a pair of polymers are also used for purification of biological material, DHBC has the remarkable advantage that the proteins and DNA segregate in the polymer-depleted phase, enhancing and facilitating purification. Future optimization of DHBC chemistry may offer higher partition efficiency and a way for large-scale applications.