Protecting-Group-Free Synthesis of Glycopolymers Bearing Sialyloligosaccharide and Their High Binding with the Influenza Virus.

Glycopolymers having pendant triazole-linked sialyloligosaccharides were successfully synthesized from free saccharides without any protection of the hydroxy and carboxy groups on the saccharides. The glycomonomers were synthesized by the direct azidation of free saccharides using 2-chloro-1,3-dimethylimidazolinium chloride as a condensing agent followed by copper(I)-catalyzed azide-alkyne cycloaddition. The resultant glycomonomers were copolymerized with acrylamide by a reversible addition-fragmentation chain transfer technique. Each of the glycopolymers were obtained and then immobilized on a gold-coated sensor of quartz crystal microbalance to analyze their binding behavior with the lectin. The glycopolymers strongly bound with the corresponding lectin without nonspecific adsorption in aqueous solution. In addition, the glycopolymer bearing a complex-type sialyl N-linked oligosaccharide was found to strongly bind with both human and avian influenza A viruses. The strong binding, observed using the hemagglutination inhibition assay, was attributed to the glycocluster effect of the glycopolymer and the biantennary structure of the N-linked oligosaccharide.