Atomic force microscopy reveals the assembly of potential DNA "nanocarriers" by poly-L-ornithine
Atomic force microscopy reveals the assembly of potential DNA "nanocarriers" by poly-L-ornithine
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DOI：
10.1016/j.bpc.2007.05.012
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发表时间：
2007-09-01
影响因子：
3.8
通讯作者：
Ganguli, Munia
中科院分区：
文献类型：
--
作者：
Mann, Anita;Khan, Meraj Alam;Ganguli, Munia
用原子力显微镜观察了聚合L异构体在云母表面的缩合过程。原子力显微镜图像显示，在较宽的DNA浓度范围内(3-20 ng/亩L)，随着正电荷聚L鸟氨酸(电荷比Z(+)/Z(-))的增加(电荷比Z(+)/Z(-)在0.1到1之间变化)的加入，负电荷的DNA通过形成几种不同的形貌发生转变。络合物的性质强烈地依赖于电荷比和DNA浓度。当脱氧核糖核酸浓度较低(类似于L 3-7 ng/亩)时，可能通过形成粗棒状的单分子络合物而引发缩合。相反，当L的DNA浓度为1320 ng/亩时，即使在低投料比下也能形成多分子结构。这种路径上的差异似乎导致了在高电荷比下形成的纳米颗粒的缩合程度以及尺寸和聚集的不同。据我们所知，这是第一次直接单分子阐明聚合L-鸟氨酸缩合DNA的机理。已知的阳离子多氨基酸，如聚L鸟氨酸，通过与脱氧核糖核酸形成浓缩的纳米载体，有效地将含有治疗基因的质粒DNA运送到各种哺乳动物细胞系中。单分子深入了解这种纳米载体在缩合过程中的包装机制，有助于预测细胞内递送和释放DNA的效果，并为设计新的基因递送载体提供重要的输入。(C)2007 Elsevier B.V.保留所有权利。
Atomic force microscopy (AFM) has been used to visualize the process of condensation of plasmid DNA by poly-L-omithine on mica surface. AFM images reveal that the transition of negatively charged DNA to condensed nanoparticles on addition of increasing amounts of positively charged poly-L-Ornithine (charge ratio (Z(+)/Z(-)) varied between 0.1 and 1) at a wide range of DNA concentrations (3-20 ng/mu l) occurs through formation of several distinct morphologies. The nature of the complexes is strongly dependent on both the charge ratio and the DNA concentration. Initiation of condensation when the concentration of DNA is low (similar to 3-7 ng/mu l) occurs possibly through formation of monomolecular complexes which are thick rod-like in shape. On the contrary, when condensation is carried out at DNA concentrations of 1320 ng/mu l, multimolecular structures are also formed even at low charge ratios. This difference in pathway seems to result in differences in the extent of condensation as well as size and aggregation of the nanoparticles formed at the high charge ratios. To the best of our knowledge, this is the first direct single molecule elucidation of the mechanism of DNA condensation by poly-L-ornithine. Cationic poly-aminoacids like poly-L-ornithine are known to be efficient in delivery of plasmid DNA containing therapeutic genes in a variety of mammalian cell lines by forming condensed "nanocarriers" with DNA. Single molecule insight into the mechanism by which such nanocarriers are packaged during the condensation process could be helpful in predicting efficacy of intracellular delivery and release of DNA from them and also provide important inputs for design of new gene delivery vectors. (c) 2007 Elsevier B.V. All rights reserved.