Jones N A, Hill I R, Stolnik S, Bignotti F, Davis S S, Garnett M C
School of Pharmaceutical Sciences, University of Nottingham, University Park, Nottingham, UK.
Biochim Biophys Acta. 2000 Dec 15;1517(1):1-18. doi: 10.1016/s0167-4781(00)00220-7.
Polyplexes are now emerging as potentially useful vectors for gene therapy. To improve our understanding of how the chemical structure of the polymer affects the properties of these systems, a series of structurally related polymers, the linear poly(amidoamine)s (PAAs), have been examined for their abilities to form complexes with DNA. Structure-dependent differences in DNA binding are shown by gel electrophoretic retardation of DNA and thermal transition analyses. Two PAAs, NG28 and NG30, stand out as having high affinity DNA binding characteristics, similar to the model homopolypeptide, poly-L-lysine. In addition, differences in complex formation, particle size and surface charge are displayed for the different polymer-DNA systems. Electron microscopy studies showed that the polymers condensed DNA into similar unit structures but only complexes with NG30 did not undergo agglomeration. This was attributed to an excess of complexed polymer forming a shell of uncomplexed polymer chain segments around a condensed DNA-polymer core. The transfection activities of these polymer complexes differ greatly, and some of these differences can be explained in a multifactorial way by the physicochemical and colloidal properties. It is concluded that polymer chemical structure dictates the apparent affinity of DNA binding, and also several of the important colloidal characteristics of the resulting complexes.
多聚体正逐渐成为基因治疗中潜在有用的载体。为了更好地理解聚合物的化学结构如何影响这些系统的性质，我们研究了一系列结构相关的聚合物——线性聚（酰胺胺）（PAA）与DNA形成复合物的能力。DNA凝胶电泳阻滞和热转变分析显示了DNA结合中结构依赖性差异。两种PAA，NG28和NG30，表现出与模型同聚多肽聚-L-赖氨酸相似的高亲和力DNA结合特性。此外，不同的聚合物-DNA系统在复合物形成、粒径和表面电荷方面存在差异。电子显微镜研究表明，聚合物将DNA浓缩成相似的单元结构，但只有与NG30形成的复合物没有发生团聚。这归因于过量的复合聚合物在浓缩的DNA-聚合物核心周围形成了一层未复合的聚合物链段外壳。这些聚合物复合物的转染活性差异很大，其中一些差异可以用物理化学和胶体性质的多因素方式来解释。得出的结论是，聚合物化学结构决定了DNA结合的表观亲和力，以及所得复合物的几个重要胶体特性。
