Chemoenzymatic synthesis of glycoconjugate polymers: greening the synthesis of biomaterials

Abstract

Glycoconjugate polymers with biodegradable poly(vinyl alcohol) (PVA) were synthesized via lipase-catalyzed transesterification of sugar alcohols (maltitol and lactitol) with divinyl dicarboxylates and subsequent radical polymerization. The conversion and chemoselectivity in transesterification were dependent on the lipases, the sugar alcohols, and the alkyl chain length of the dicarboxylates. Chemoselective esterification was attained in the presence of lipase from Candida antarctica (lipase CA) to give maltitol 6-vinyl sebacate, lactitol 6-vinyl sebacate, and lactitol 6-vinyl adipate in high yields. Polymerization of these vinyl esters with hydrogen peroxide/ascorbic acid as initiator gave glycoconjugate polymers. These polymers were suggested to take micellar conformations in water and to bind strongly to specific lectins (concanavalin A or RCA₁₂₀). The biodegradabilities of these polymers were modest but higher than PVA. This simple synthesis will be useful to develop various glycoconjugate polymers with high biological activities due to the multivalent glyco-cluster effect and biodegradability due to their PVA backbone and ester linkage.