Facile Synthesis of Fluorescent Latex Nanoparticles with Selective Binding Properties Using Amphiphilic Glycosylated Polypeptide Surfactants

Abstract

Block copolymers comprising a poly(styrene) and a poly(l-lysine) or poly(l-glutamic acid) block were obtained by sequential reversible addition–fragmentation chain Transfer (RAFT) and N-carboxyanhydride (NCA) polymerization. Subsequent partial glycosylation of the poly(l-glutamic acid) block with d-galactosamine (GA) and the poly(l-lysine) block with lactobionic acid (LA) yielded block copolymers with a degree of glycosylation of 50% and 35%, respectively, in the poly(amino acid) block. These amphiphilic block copolymers were successfully employed as macromolecular surfactants in the emulsion polymerization of styrene to produce uniform 100–150 nm size nanoparticles with a poly(syrene) core and galactose containing poly(l-amino acid) periphery. Introduction of fluorescence was achieved by incorporation of Nile Red during latex formation and reaction of remaining lysine functionalities on the nanoparticle periphery with fluorescein isothiocyanate (FITC). The availability of the galactose units at the nanoparticles surface for selective binding was demonstrated by lectin binding experiments and binding to Chinese hamster ovary (CHO) cells. Confocal images of live CHO cells following incubation with fluorescent glycosylated nanoparticles confirmed that the nanoparticles bound strongly to the cell surface and could only be removed by addition of free lactobionic acid, highlighting selective binding of the nanoparticles on the cell surface.