Synthesis and self-assembly of branched glycopolypeptides: effect of topology and conformation

Block copolymers combining peptide and saccharide moieties may play a significant role in future applications of polymers in biology, as they can be viewed as simplified synthetic analogues of glycosylated proteins, which display a wide range of biological functions in nature. While a small number of oligosaccharides containing synthetic polypeptides have been described so far, here we present the efficient preparation of a small library of tree-like glycopolypeptides incorporating poly(gamma-benzyl-L-glutamate) having different molecular weights. A comprehensive study of the self-assembly of these unique grafted macromolecular structures is detailed. All the copolymers presented the ability to spontaneously self-assemble into spherical micelles in water; a property assigned both to the spontaneous curvature of the grafted oligosaccharide segments and to the favorable hydrophilic to hydrophobic volume ratios. These hydrophilic to hydrophobic volume ratios were efficiently counterbalanced by the self-assembly of blends incorporating poly(gamma-benzyl-L-glutamate) homopolymers - this simple approach minimized the influence of the spontaneous curvature of the oligosaccharides' dendrons and afforded a transition to lamellar structures in solution.