Synthesis of poly[2-(α-d-mannopyranosyloxy)ethyl-co-2-dimethylaminoethyl methacrylates] and its lectin-binding and DNA-condensing properties

Radical copolymerizations of 2-(α-d-mannopyranosyloxy)ethyl methacrylate (ManEMA) with 2-dimethylaminoethyl methacrylate (DMAEMA) were carried out in N,N-dimethylformamide (DMF) containing 10 vol% water at 60 °C to yield cationic glycopolymers. The number-average molecular weights (Mns, standard Pullulan calibration) and polydispersities (Mw/Mns) of the resulting copolymers were ranged from 17,400 to 41,700 and from 1.7 to 3.2, respectively. The compositions of the resulting copolymers were very close to those in the feed. The monomer reactivity ratios rManEMA and rDMAEMA were 0.98 and 1.22, respectively. The lectin-binding properties of poly(ManEMA-co-DMAEMA) to concanavalin A (ConA) was examined using a turbidimetric assay. The clustering rate increased with increasing mole fractions of the ManEMA units in the copolymer (FManEMA), even under a constant concentration of the ManEMA units (50 μM), indicating the typical cluster glycoside effect. The DNA-condensing ability of the resulting copolymers was examined by a gel retardation assay using pEGFP-N1 plasmid (4.7 kbp). Though the ManEMA units interfered with the complexation of the copolymer with the plasmid DNA, complete retardation was observed under the condition of lower contents of ManEMA units (FManEMA < 0.2) in pure water. These findings indicate that poly(ManEMA-co-DMAEMA) is a cationic glycopolymer exerting lectin-binding and DNA-condensing abilities.