Lin Song, Du Fusheng, Wang Yang, Ji Shouping, Liang Dehai, Yu Lei, Li Zichen
Beijing National Laboratory for Molecular Sciences, Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, College of Chemistry & Molecular Engineering, Peking University, Beijing 100871, PR China.
Biomacromolecules. 2008 Jan;9(1):109-15. doi: 10.1021/bm7008747. Epub 2007 Dec 19.
Intelligent gene delivery systems based on physiologically triggered reversible shielding technology have evinced enormous interest due to their potential in vivo applications. In the present work, an acid-labile block copolymer consisting of poly(ethylene glycol) and poly(2-(dimethylamino)ethyl methacrylate) segments connected through a cyclic ortho ester linkage (PEG- a-PDMAEMA) was synthesized by atom transfer radical polymerization of DMAEMA using a PEG macroinitiator with an acid-cleavable end group. PEG- a-PDMAEMA condensed with plasmid DNA formed polyplex nanoparticles with an acid-triggered reversible PEG shield. The pH-dependent shielding/deshielding effect of PEG chains on the polyplex particles were evaluated by zeta potential and size measurements. At pH 7.4, polyplexes generated from PEG- a-PDMAEMA exhibited smaller particle size, lower surface charge, reduced interaction with erythrocytes, and less cytotoxicity compared to PDMAEMA-derived polyplexes. At pH 5.0, zeta potential of polyplexes formed from PEG- a-PDMAEMA increased, leveled up after 2 h of incubation and gradual aggregation occurred in the presence of bovine serum albumin (BSA). In contrast, the stably shielded polyplexes formed by DNA and an acid-stable block copolymer, PEG- b-PDMAEMA, did not change in size and zeta potential in 6 h. In vitro transfection efficiency of the acid-labile copolymer greatly increased after 6 h incubation at pH 5.0, approaching the same level of PDMAEMA, whereas there was only slight increase in efficiency for the stable copolymer, PEG- b-PDMAEMA.
基于生理触发的可逆屏蔽技术的智能基因递送系统因其在体内的应用潜力而引起了极大的关注。在本研究中，通过使用具有酸可裂解端基的聚乙二醇（PEG）大分子引发剂对甲基丙烯酸2-（二甲氨基）乙酯（DMAEMA）进行原子转移自由基聚合，合成了一种由聚乙二醇和聚甲基丙烯酸2-（二甲氨基）乙酯链段通过环状原酸酯键连接而成的酸敏性嵌段共聚物（PEG-a-PDMAEMA）。PEG-a-PDMAEMA与质粒DNA缩合形成具有酸触发可逆PEG屏蔽的多聚体纳米颗粒。通过zeta电位和尺寸测量评估了PEG链对多聚体颗粒的pH依赖性屏蔽/去屏蔽效应。在pH 7.4时，与源自PDMAEMA的多聚体相比，由PEG-a-PDMAEMA产生的多聚体表现出更小的粒径、更低的表面电荷、与红细胞的相互作用减少以及细胞毒性更小。在pH 5.0时，由PEG-a-PDMAEMA形成的多聚体的zeta电位增加，孵育2小时后趋于稳定，并且在牛血清白蛋白（BSA）存在下会逐渐聚集。相比之下，由DNA和酸稳定嵌段共聚物PEG-b-PDMAEMA形成的稳定屏蔽多聚体在6小时内尺寸和zeta电位没有变化。在pH 5.0孵育6小时后，酸敏性共聚物的体外转染效率大大提高，接近PDMAEMA的水平，而稳定共聚物PEG-b-PDMAEMA的效率仅略有增加。
