CMC-g-DNA接枝共聚物的合成与表征

在磷酸盐缓冲溶液中用1-(3-二甲氨基丙基)-3-乙基碳二亚胺(EDC)与N-羟基琥珀酰亚胺(NHS)活化羧甲基纤维素钠(CMC)侧链上的羧基; 在室温下再将活化的CMC与5'端经氨基修饰的单链脱氧核糖核酸(DNA)齐聚物(ODNs)反应, 获得CMC上接枝ODNs的共聚物(CMC-g-ODNs), 以Lambda DNA为模板, 通过聚合酶链式反应(PCR), 将接枝的ODNs扩增为长度为1300个碱基对的双链DNA, 从而制得CMC侧链上接枝DNA的共聚物CMC-g-DNA. 采用傅里叶红外光谱仪测定CMC与NHS形成的中间体; 用水平式琼脂糖凝胶电泳和垂直板变性聚丙烯酰胺凝胶电泳对CMC-g-DNA接枝共聚物进行表征. 结果表明, 合成了CMC-g-DNA接枝共聚物, 且在酸性条件下CMC的活化效果更好; 同时, 接枝在CMC上的DNA在琼脂糖凝胶电泳中迁移速率加快, 而在聚丙烯酰胺凝胶电泳中迁移速率减慢.

Preparation and Characterization of the CMC-g-DNAHybrid Copolymers†

Sodium carboxymethyl cellulose grafted DNA(CMC-g-DNA) hybrid copolymer, which can be a potential gene drug, was synthesized and characterized by both chemical and biological methods. First, the carboxyl groups on the side chain of CMC were activated by both 1-(3-dimethylaminopropyl)-3-ethylcarbo-diimide(EDC) and N-hydroxy-succinimide(NHS) in phosphate buffer at both neutral and acid condition, respectively. After that, the CMC-NHS reacted with amino-functionalized oligodeoxynucleotides(NH₂-ODNs) to get CMC-g-ODNs grafted copolymer. Then CMC-g-ODNs were used as forward primers for the next-step polymerase chain reaction(PCR) to generate the final CMC-g-DNA hybrid copolymer. The infrared spectrum detection proved that the side carboxyl groups of the CMC were substituted very well by NHS and the efficiency was higher at acid condition than neutral. The obtained CMC-g-DNA copolymers were characterized by agarose gel electrophoresis and polyacrylamide gel electrophoresis, respectively. And the results showed that DNA was grafted on CMC successfully. An interesting finding is that CMC-g-DNA moved faster than control DNA in agarose gel electrophoresis, while it migrated slower than control polyacrylamide gel electrophoresis.