From polymer sequence control to protein recognition : synthesis, self-assembly and lectin binding

A novel, highly efficient methodology to synthesize gradient glycopolymers has been successfully developed involving concurrent enzymatic monomer transformation and reversible addition–fragmentation chain transfer (RAFT) polymerization. By synchronizing enzymatic monomer transformation with polymerization, a continuous supply of the second monomer (glycomonomer) is achieved during the polymerization, resulting in a gradient sugar distribution in the final polymer. Detailed studies of the process using GPC and NMR indicate that the gradient glycopolymers synthesized by RAFT were well controlled. Subsequently, 1,2:3,4-di-O-isopropylidene-6-O-methacryloyl-α-d-galactopyranose (DIMAG) moieties were deprotected to regenerate the sugar and achieve amphiphilic bioactive glycopolymers. We demonstrate the synthesis of a set of glycopolymers with different sequential structures, such as statistical, gradient and block glycopolymers. The glycopolymers with block structure show higher affinities toward the RCA120 lectin receptor compared with other structural counterparts. Furthermore, simulation of the self-assembly of three types of copolymers and their binding to lectins provides fundamental insight into this result, revealing the mechanisms underlying the dependence of self-assembling structures and protein adsorption kinetics on the molecular architectures of copolymers