含磺酸基半乳糖高分子的合成及与凝集素相互作用研究

Preparation of Sulfonated Galactose-based Glycopolymers and Interactions with Lectins

以含半乳糖的甲基丙烯酸羟乙酯和对苯乙烯磺酸钠为单体,通过可逆加成断裂链转移聚合设计合成了一系列具有不同结构的含糖高分子.采用核磁共振氢谱和凝胶渗透色谱对材料的结构进行了表征.分别通过比浊法和酶联免疫吸附实验,以花生凝集素(PNA)为模型,研究了磺酸基的数量及分布对材料与凝集素之间相互作用的影响.结果表明,磺酸基的引入能通过静电相互作用协同增强含半乳糖高分子与PNA之间的特异性结合作用,并且这一作用可通过磺酸基数量与排列方式进行调节,相对于嵌段共聚型材料,无规共聚型材料与PNA的结合作用更强,其中P(Gal21-r-SS41)与PNA的结合作用最强,较均聚半乳糖高分子(PGal)提高2.7倍.利用这种相互作用,材料能够通过阻断凝集素活性有效抑制肿瘤细胞的迁移,有望在临床抗肿瘤转移治疗中得以应用.

A series of sulfonated galactose-based glycopolymers with different chemical structures were synthesized through reversible addition-fragmentation chain transfer （RAFT） polymerization. Galactose modified hydroxyethyl methacrylate and sodium p-styrene sulfonate were used as monomers to construct homo-, block-, and random-glycopolymers. The chemical structures and molecular weights of the synthesized polymers were characterized through 1H-NMR spectroscopy and GPC-MALLS analyses. Results showed that each glycopolymer possessed an average molecular weight of 1.5 × 10^4 with narrow molecular weight distribution （PDI - 1.1）. The turbidimetry assay indicated that the interactions between the glycopolymers and peanut agglutinin （PNA）, which were used as model lectin, were influenced by the structure of the glycopolymers. The introduction of the sulfonic group significantly improved the PNA-binding ability of the glycopolymers through the synergistic effect of specific recognition and electrostatic interactions. Importantly, this effect was adjustable by varying the amount and distribution of the sulfonic groups. Both block- and random-glycopolymers exhibited significantly enhanced PNA-binding behavior with increasing amount of sulfonic groups. Moreover, the binding ability peaked when the molar ratio of the sulfonic groups was 66.7%. By contrast, the random-type glycopolymer, namely, P（Ga121-r-SS41）, exhibited the strongest PNA-binding ability, which increased by 2.7-fold compared with that of the homo-type glycopolymer PGal. The ELISA assay further revealed that the polymerization and random distribution of the sulfonic groups in the glycopolymer substantially enhanced the recognition between PNA and the galactose moiety. The inhibition rate of galactose （30 mmol/L） against the PNA binding of PGal, P（Ga121-b-SS43）, and P（Ga121-r-SS41） were 80%, 57.3%, and 34.2%, respectively. However, the contents of the galactose moiety in these samples were 3.8, 2.1 and 2.0 mmol/L, respectively. Overall, the order of PNA-binding ability was： P（Gal-r-SS） 〉 P（Gal-b-SS） 〉 PGal 〉 PSS. In addition, the viability of B16 cancer cells and COS7 normal cells was higher than 80% when the concentration of the glycopolymers was 256 mg/L, indicating a good biocompatibility of these polymers. Based on the analysis of glycopolymer-lectin interactions, P（Ga121-r-SS40 effectively inhibited the migration of B16 tumor cells and thus can be applied in clinical therapy for tumor metastasis.