Colloidal Structure and Stability of DNA/Polycations Polyplexes Investigated by Small Angle Scattering

详细信息    查看全文

• 作者：Sylvain Pr茅vost ; Sven Riemer ; Wiebke Fischer ; Rainer Haag ; Christoph B枚ttcher ; J茅r茅mie Gummel ; Isabelle Grillo ; Marie-Sousai Appavou ; Michael Gradzielski
• 刊名：Biomacromolecules
• 出版年：2011
• 出版时间：December 12, 2011
• 年：2011
• 卷：12
• 期：12
• 页码：4272-4282
• 全文大小：591K
• 年卷期：v.12,no.12(December 12, 2011)
• ISSN：1526-4602

文摘

Polyplexes of short DNA-fragments (300 b.p., 100 nm) with tailor-made amine-based polycations of different architectures (linear and hyperbranched) were investigated in buffer solution as a function of the mixing ratio with DNA. The resulting dispersed polyplexes were characterized using small-angle neutron and X-ray scattering (SANS, SAXS) as well as cryo-TEM with respect to their mesoscopic structure and their colloidal stability. The linear polyimines form rather compact structures that have a high tendency for precipitation. In contrast, the hyperbranched polycation with enzymatic-labile pentaethylenehexamine arms (PEHA) yields polyplexes colloidally stable for months. Here the polycation coating of DNA results in a homogeneous dispersion based on a fractal network with low structural organization at low polycation amount. With increasing polycation, bundles of tens of aligned DNA rods appear that are interconnected in a fractal network with a typical correlation distance on the order of 100 nm, the average length of the DNA used. With higher organization comes a decrease in stability. The 3D network built by these beams can still exhibit some stability as long as the material concentration is large enough, but the structure collapses upon dilution. SAXS shows that the complexation does not affect the local DNA structure. Interestingly, the structural findings on the DNA polyplexes apparently correlate with the transfection efficiency of corresponding siRNA complexes. In general, these finding not only show systematic trends for the colloid stability, but may allow for rational approaches to design effective transfection carriers.