Choi Yi-Rac, Chae Su Young, Ahn Cheol-Hee, Lee Minhyung, Oh Seungjoon, Byun Youngro, Rhee Byoung Doo, Ko Kyung Soo
Department of Materials Science and Engineering, Hyperstructured Organic Materials Research Center (HOMRC), Seoul National University, Seoul, South Korea.
J Drug Target. 2007 Jul;15(6):391-8. doi: 10.1080/10611860701401561.
Block copolymers consisting of poly(ethylene glycol) (PEG) and poly(amino acid)-based random copolymers were successfully synthesized by the ring opening polymerization of the N-carboxy anhydrides (NCA) of L-lysine and L-phenylalanine. The synthesized copolymers had a molecular weight of around 30,000 and contained L-lysine and L-phenylalanine residues with molar ratios of 10/0, 9/1, 8/2, 7/3 and 6/4. The complex formation of the copolymer and pCMV-luc plasmid DNA was confirmed by the gel retardation assay and zeta potential measurement. Complete neutralization was achieved at an N/P ratio of more than 1.0 and the size of the complex was determined to be around 150 nm by dynamic light scattering. The cytotoxicity and transfection efficiency were tested on the HEK 293T cell line. The synthesized copolymers displayed negligible cytotoxicity, resulting in a cell viability of more than 95%, while those of the poly(L-lysine) (PLL) and poly(ethylenimine) (PEI) homopolymer were around 65 and 55%, respectively, under comparable conditions. The introduction of the hydrophilic PEG is believed to reduce the toxicity of the copolymer, due to its enhanced biocompatibility, and to impart improved stability to the complex under physiological conditions. The transfection efficiency at the optimized charge ratio of 7 was dramatically improved as the molar content of the L-phenylalanine residues in the copolymers increased and reached a maximum value at an L-phenylalanine content of 30 mol%. The transfection efficiency of the PEGK7/plasmid DNA complex was around 80 times higher than that of PLL, despite the presence of neutral PEG as a block segment.
通过L-赖氨酸和L-苯丙氨酸的N-羧基酸酐（NCA）的开环聚合反应，成功合成了由聚乙二醇（PEG）和基于聚氨基酸的无规共聚物组成的嵌段共聚物。合成的共聚物分子量约为30000，含有摩尔比为10/0、9/1、8/2、7/3和6/4的L-赖氨酸和L-苯丙氨酸残基。通过凝胶阻滞试验和zeta电位测量证实了共聚物与pCMV-luc质粒DNA的复合物形成。当N/P比大于1.0时实现了完全中和，通过动态光散射测定复合物的尺寸约为150nm。在HEK 293T细胞系上测试了细胞毒性和转染效率。合成的共聚物显示出可忽略不计的细胞毒性，细胞活力超过95%，而在可比条件下，聚（L-赖氨酸）（PLL）和聚（乙烯亚胺）（PEI）均聚物的细胞活力分别约为65%和55%。据信，亲水性PEG的引入由于其增强的生物相容性而降低了共聚物的毒性，并在生理条件下赋予复合物更好的稳定性。随着共聚物中L-苯丙氨酸残基的摩尔含量增加，在优化电荷比为7时的转染效率显著提高，并在L-苯丙氨酸含量为30mol%时达到最大值。尽管存在中性PEG作为嵌段链段，但PEGK7/质粒DNA复合物的转染效率比PLL高约80倍。
