Synthesis Of Heterogeneous Glycopolymers By RAFT Polymerization And ROMP Polymerization And Their Specific Recognition Of Lectin

Heterogeneous glycopolymers with different sugar units in the side chain have been receiving considerable attention due to their potential properties in enhancing molecular recognition abilities toward a specific protein receptor.By far only a handful of well-defined heteroglycopolymers have been prepared by either the direct polymerization of sugar-bearing monomers or post-functionalization strategies of precursor polymers,which aimed to investigate the heteromultivalent effect and binding ability between different sugar units and lectins.However,due to the steric hindrance of the side chain,the yields of glycopolymers produced by direct polymerization of glycomonomers are usually low,and glycomonomers often require tedious organic synthesis steps.Post-polymerization modification(PPM)as an efficient and versatile polymer preparation strategy to prepare heterogeneous glycopolymers via attaching pre-synthesized side chains with different sugar units onto a polymer backbone,could circumvent steric hindrance and possible compatibility issues between desired sugar units and polymerization.Therefore,how to use an efficient post-polymerization modification strategy to prepare heterosaccharide polymers with different sugar units in the side chains has become a research hotspot.Herein,the functionalized amines bearing two different sugar motifs have been synthesized by gradient Cu AAC reaction,which could serve as a platform for achieving heterogeneous sugar units with functional control in concise steps.Then,a series of heterogeneous glycopolymers containing different sugar units in the side chain were synthesized by using activated RAFT polymerization and post-polymerization modification(PPM)technology.Turbidimetric assay and isothermal titration calorimetry(ITC)measurements were carried out to examine the specific binding ability of heteroglycopolymers to lectin(Con A)as compared to homoglycopolymers and monoglycopolymers.The heterogeneous glycopolymers bearing α-mannose and other non-binding sugar motifs show high affinities toward Concanavalin A(Con A)in comparison to the monomannose polymer which suggested the heterogeniety in the glycopolymers has a synergistic effect on glycopolymer-letin binding behavior.In addition,Ring-opening metathesis polymerization(ROMP)is widely used to prepare functional glycopolymers due to mild reaction conditions and controllable activity.We tend to use ring-opening metathesis polymerization(ROMP)and copper-catalyzed azide–alkynecycloaddition(Cu AAC)reactions to prepare glycopolymers with different groups in the side chains.This work allows for precise fabrication of a broad variety of glycopolymers in which it significantly broadens the library of polymer structures,either homogeneous or heterogeneous glycopolymers,and has certain guiding significance for the preparation of functional dendrimer materials.