Synthesis of polystyrene nanospheres having lactose-conjugated hydrophilic polymers on their surfaces and carbohydrate recognition by proteins

Abstract

We prepared a poly(vinylamine)-grafted polystyrene nanosphere by the free radical polymerization of poly(N-vinylacetamide) macromonomer and styrene with AIBN in ethanol and subsequent acid hydrolysis. We conjugated lactose on the nanosphere by an amide linkage and found that the lactose was recognized by a galactose-specific lectin RCA₁₂₀, which was analyzed by enzyme-linked lectin assay (ELLA). The binding ability of the lectin to lactose on the nanosphere was at least 10² times larger than that to a monomeric lactose. Binding ability was clearly affected by the lactose density on the nanosphere and showed a maximum value at the suitable surface density of lactose. We found that the carbohydrate-conjugated nanosphere would be a useful biomaterial for a site specific drug carrier.

Keywords:

• Polystyrene nanosphere
• macromonomer
• carbohydrate
• recognition
• enzyme-linked lectin assay