Glycopolymer Decoration of Gold Nanoparticles Using a LbL Approach

Two different copolymers, i.e., poly(tert-BuA-co-chloromethylstyrene) and poly(tert-BuA-co-HEA), were synthesized by reversible addition fragmentation (RAFT) polymerization. A poly(tert-BuA-co-chloromethylstyrene) copolymer was subsequently modified by thioglucose using a thio halogen click nucleophilic substitution reaction. A poly(tert-BuA-co-HEA) copolymer was subsequently modified by p-toluenesulfonyl chloride, followed by sugar functionalization (galactose) via a nucleophilic substitution reaction. The resultant glycopolymers were characterized by NMR, FTIR, and GPC analyses. Both glyco-modification procedures were shown to be highly efficient with yields close to 100%. After deprotection of the tert-butyl groups to form carboxylic acid functionality, the copolymers were assembled onto positively charged gold nanoparticle (GNPs) surfaces using a layer-by-layer (LbL) methodology to yield sugar-functional GNPs. The glycopolymer-coated nanoparticles were characterized by transmission electron microscopy (TEM), UV-vis spectroscopy, dynamic light scattering (DLS), zeta-potential, and X-ray photoelectron spectroscopy (X PS). Finally, the presence of accessible sugar moieties on the surface of the GNPs was confirmed by a binding assay with Con A.