Preparation of multifunctional glycopolymers using double orthogonal reactions and the effect of electrostatic groups on the glycopolymer–lectin interaction

Abstract

We investigated synthetic biomacromolecules to control molecular interactions. Multifunctional glycopolymers for molecular recognition were prepared via living radical polymerization and post-click chemistry with orthogonal Huisgen and thiol-epoxy reactions. The synthesis of the polymer backbone and the subsequent side-chain introduction successfully proceeded in high yield. The multifunctional glycopolymers had a tri-block structure: the first and third blocks contained mannose, and the second block contained either a positively or negatively charged group or a neutral hydrophilic group. The molecular recognition of the glycopolymers toward lectin was evaluated via fluorescence quenching measurements. Because of the electrostatic interaction, the binding constant varied in the following order: positively charged glycopolymer (PT110) > negatively charged glycopolymer (NT110). The effect of the electrostatic interactions was modest compared with the effect of the carbohydrate–lectin binding. These results suggested that the carbohydrate–lectin interaction was an important factor in the molecular recognition of glycopolymers. This study provides guidelines for the preparation of multifunctional polymers, such as biomaterials. The block glycopolymers with specific arrangement of sugar ligand and electric charges were synthesized via RAFT living radical polymerization, where the block polymers were efficiently obtained using two orthogonal reactions of Huisgen and thiol-epoxy ring opening reactions. The molecular recognition abilities of the block glycopolymers was examined.