Polymeric vesicles mimicking glycocalyx (PV-Gx) for studying carbohydrate–protein interactions in solution

Glycocalyx, the carbohydrate coat on cell surfaces, has been proved to be particularly important in a variety of biological events. In this work, polymeric vesicle mimicking of glycocalyx (PV-Gx), as a simplified model system, is achieved via our NCCM (non-covalently connected micelles) strategy. Briefly, a thermal responsive poly(N-isopropylacrylamide) with phenylboronic acid (BA) end (BA-PNIPAM) and two novel hydrophilic glycopolymers, PGal and PGlc are prepared by RAFT polymerization, where the latter are prepared from N-linked β-pyranoside monomers containing respective units of galactoside (Gal) and glucoside (Glc). Upon heating PNIPAM-BA and PGal (PGlc) self-assemble into vesicles V-PGal (V-PGlc), driven by the dynamic covalent bond between sugars and BA. Both V-PGal and V-PGlc could serve as our target artificial glycocalyx (PV-Gx) because they have sugar-coated surfaces and disperse stably in water. Dynamic light scattering (DLS) has been employed to monitor the binding process between the sugars on PV-Gx and three lectins i.e. Arachis hypogaea (PNA), Erythrina cristagalli (ECA) and Concanavalin A (Con A), concluding that the PV-Gx shows clear specificities in the sugar-protein interactions: V-PGal interacts well with PNA and ECA to form aggregates but not with ConA, while V-PGlc interacts with none of the lectins. The results clearly prove that the PV-Gx constructed from the polymers with well-defined sugar units is a new and promising platform for the study of carbohydrate-protein interactions in solution.