Amphiphilic Polycations for Nucleic Acid Delivery

描述(由申请人提供)：在细胞内传递不透膜的分子，如核酸，通常的策略是使用膜活化剂，它使膜通透，从而促进细胞质传递。膜活化剂往往是两亲性的，即既含有疏水官能团又含有亲水官能团。对于核酸的输送，膜活化剂也是阳离子的，这导致与核酸的结合被输送。 尽管具有电荷密度和络合物稳定性，两亲性、膜活性的阳离子聚合物作为DNA递送试剂的利用率远远低于阳离子脂类。研究最充分、膜活性最强的阳离子聚合物是小分子阳离子多肽。这些阳离子多肽能够直接与待传递的DNA相互作用。然而，与较大的聚阳离子相比，它们与DNA的相互作用相对较弱。这项研究计划的重点是开发阳离子、膜活性聚合物，这种聚合物体积大，电荷密度大，足以与核酸形成稳定的络合物。我们的膜活性聚阳离子的合成将受到阳离子膜活性多肽的两亲性组成的指导，这些活性多肽具有疏水性和阳离子残基的倾向。 在我们设计的两亲性聚合物合成后，我们将测试它们的两个特征，我们认为这两个特征是核酸传递的关键：与DNA相互作用的能力，以及破坏脂质双层的能力。然后，这些聚合物将接受测试，以确定它们是否能够传递质粒DNA和短干扰RNA，这两种核酸的大小和传递要求不同。我们预计，我们的合成聚合物的转染能力将与它们的膜裂解能力和核酸结合能力相关。此外，确定转染、裂解和结合之间的关系将为药物和基因转移试剂的设计建立新的策略。

DESCRIPTION (provided by applicant): A common strategy for the intracellular delivery of membrane-impermeable molecules such as nucleic acids is the use of membrane active agents, which permeabilize membranes thus facilitating cytoplasmic delivery. Membrane active agents tend to be amphiphilic, i.e. contain both hydrophobic and hydrophilic functional groups. For the delivery of nucleic acids, membrane active agents are also cationic, which causes binding to the nucleic acid to be delivered. Despite to their charge density and complex stability, amphiphilic, membrane-active, cationic polymers are much less utilized than cationic lipids as DNA delivery reagents. The most well-studied, membrane-active, cationic polymers are small cationic peptides. These cationic peptides are able to interact directly with the DNA to be delivered. However, their interactions with DNA are relatively weak compared to larger polycations. This research proposal is focused on the development of cationic, membrane-active polymers that are large and charge dense enough to form stable complexes with nucleic acids. Our synthesis of membrane active polycations will be guided by the amphiphilic composition of cationic membrane active peptides, which have propensity of hydrophobic and cationic residues. Upon synthesis of our designed amphiphilic polymers, we will test them for the two characteristics that we believe to be key to the delivery of nucleic acids: the ability to interact with DNA, and the ability to disrupt lipid bilayers. The polymers will then be tested for their ability to deliver plasmid DNA and short interfering RNA, two nucleic acids of different size and delivery requirements. We anticipate that the transfection ability of our synthetic polymers will correlate with their membrane lytic and nucleic acid binding abilities. In addition, the determination of the relationships among transfection, lysis and binding will establish new strategies for the design of drug and gene transfer reagents.