Formulation of PEG–folic acid coated nanometric DNA particles from perfluoroalkylated cationic dimerizable detergents and in vitro folate-targeted intracellular delivery
作者:Loïc Le Gourriérec、Christophe Di Giorgio、Jacques Greiner、Pierre Vierling
DOI:10.1039/b806043f
日期:——
Present attempts in gene delivery mediated with synthetic vectors are now oriented towards the formulation of nanometric DNA complexes reminiscent of viruses. The assembly of such multifunctional gene transfer systems was designed in order to take advantages of viral vector properties. This requires, among others, the formulation of very small- and homogeneously-sized âstealthâ as well as ligand-labeled DNA nanoparticles. In this paper, we report the straightforward synthesis of an original dimerizable perfluoroalkylated thiol detergent deriving from cysteine and containing a monocationic aminotriethylene glycol and of a known analog containing a tricationic linear spermine polar head (three steps, 45â50% overall yields). These derivatives condensed DNA into a monodisperse population of negatively or positively charged, virus-sized (â¼40â80 nm) [F-detergent]2/DNA nanoparticles, as confirmed by zeta potential and agarose gel electrophoresis experiments. These stable nanoparticles consisted likely of monomolecular DNA particles although particles containing a very few copies of DNA could not be excluded. These constructs were obtained following a monomolecular DNA condensation process occurring when DNA is mixed with a cationic detergent at a concentration close to its critical micellar concentration, the resulting complexes being subsequently stabilized upon oxidation of the thiol detergent into its disulfide lipidic dimer ([F-detergent]2) on the DNA matrix. DNA was also shown to be fully protected, not accessible, when condensed into cationic nanoparticles. The surface of these particles was further labeled with an amphiphilic-polyethyleneglycolâfolic acid conjugate, as attested by zeta potential measurements. Size measurements and TEM analysis showed nanometric sizes (â¤100 nm) for these labeled DNA nanoparticles. Noticeably with respect to their very low size, we found that the cationic, uncoated [F-detergent]2/DNA formulations were efficient ânon-specificâ transfection agents of KB cells and particularly more efficient than PEI polyplexes. However, though FACS analysis with (un)coated and YOYO-labeled [F-detergent]2/DNA nanoparticles showed specific uptake of the folic acid coated nanoparticles into folate-overexpressing KB cells, transfection experiments relying on luciferase expression measurements did not show any specific improvement of gene expression resulting from such a targeting.
目前,以合成载体为介导的基因传递尝试主要针对纳米 DNA 复合物的配制,让人联想到病毒。设计这种多功能基因传输系统的目的是利用病毒载体的特性。这就要求,除其他外,配制出非常小且大小均匀的 "隐形 "以及配体标记的 DNA 纳米颗粒。在本文中,我们报告了一种源自半胱氨酸、含有单配位氨基三乙二醇的原始可二聚化全氟烷基硫醇去垢剂和一种含有三阳离子线性精胺极性头的已知类似物的直接合成方法(三个步骤,总产率 45%-50%)。经ZETA电位和琼脂糖凝胶电泳实验证实,这些衍生物可将DNA凝结成单分散的带负电或带正电的病毒大小(§40â80 nm)的[F-洗涤剂]2/DNA纳米颗粒。这些稳定的纳米颗粒很可能由单分子DNA颗粒组成,但也不排除含有极少量DNA拷贝的颗粒。当 DNA 与阳离子去垢剂混合后,浓度接近其临界胶束浓度时,就会发生单分子 DNA 缩合过程,随后硫醇去垢剂氧化成 DNA 基质上的二硫化脂质二聚体([F-去垢剂]2),由此产生的复合物就会稳定下来。研究还表明,当 DNA 被凝结成阳离子纳米粒子时,DNA 会受到完全保护,无法被接触到。ZETA电位测量结果表明,这些颗粒的表面进一步标记了两性-聚乙二醇-叶酸共轭物。尺寸测量和 TEM 分析表明,这些标记的 DNA 纳米粒子具有纳米级尺寸(§100 nm)。值得注意的是,我们发现阳离子、无包被的[F-去垢剂]2/DNA制剂是KB细胞的高效 "非特异性 "转染剂,尤其比PEI多聚体更有效。不过,尽管使用(未)包被和YOYO标记的[F-洗涤剂]2/DNA纳米颗粒进行的FACS分析表明,叶酸包被的纳米颗粒能特异性地被叶酸缺失的KB细胞吸收,但根据荧光素酶表达测量进行的转染实验并未显示这种靶向性对基因表达有任何特异性改善。