Modulation of Multivalent Protein Binding on Surfaces by Glycopolymer Brush Chemistry

The presentation of carbohydrates on an array can provide a means to model (mimic) oligosaccharides found on cell surfaces. Tuning the structural features of such carbohydrate arrays can therefore be used to help to elucidate the molecular mechanisms of protein-carbohydrate recognition on cell surfaces. Here we present a strategy to directly correlate the molecular and structural features of ligands presented on a surface with the kinetics and affinity of carbohydrate-lectin binding. The Surface Plasmon Resonance (SPR) spectroscopy analysis identified that by varying the spatial distribution (3D organization) of carbohydrate ligands within the surface grafted polymer layer, the mode of binding changed from multivalent to monovalent: a near 1000-fold change in the equilibrium association constant was achieved. The rupture forces measured by atomic force microscopy (AFM) force spectroscopy also indicated that the mode of binding between lectin and carbohydrate ligands can be modulated by the organization of carbohydrate ligands within the glycopolymer brushes.