Rackstraw Benjamin J, Stolnik Snjezana, Davis Stanley S, Bignotti Fabio, Garnett Martin C
School of Pharmaceutical Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, UK.
Biochim Biophys Acta. 2002 Jul 19;1576(3):269-86. doi: 10.1016/s0167-4781(02)00347-0.
PEGylated polyamidoamine (PAA) polymers were investigated for the production of sterically stabilised DNA delivery systems. Comparison of a PEGylated polymer (NG47) with a non-PEGylated polymer (NG49) showed similar binding of co-polymer to DNA by displacement of ethidium bromide (EB) and DNA melting studies. Gel electrophoresis, turbidimetric analysis and PCS demonstrated differences in the colloidal properties of the complexes, which were attributable to the formation of soluble complexes by the PEGylated co-polymer. However, transmission electron microscopy (TEM) showed that the resulting complexes containing poly(ethylene glycol) (PEG) were not well condensed, susceptible to degradation by nucleases, and thus not suited for in vivo delivery. The poor properties of the PEGylated co-polymer were attributed to an excess of PEG. However, polymer blends of NG47 and NG49 at defined ratios of polymer to co-polymer and total repeating units (RUs) to nucleotide, spontaneously formed complexes with a range of desirable properties. These included small size and polydispersity, high particle density, low surface charge and resistance to nuclease degradation. Complexes made with PEGylated polymer alone, and the polymer blends both suffered from a reduced polyfection activity. This was attributed to a low surface charge on the complex, which reduced interactions with the cell membrane and consequent uptake of the particles into the cell.
研究了聚乙二醇化聚酰胺胺（PAA）聚合物用于制备空间稳定的DNA递送系统。通过溴化乙锭（EB）置换和DNA熔解研究，将聚乙二醇化聚合物（NG47）与非聚乙二醇化聚合物（NG49）进行比较，结果显示共聚物与DNA的结合相似。凝胶电泳、比浊分析和粒度分析表明复合物的胶体性质存在差异，这归因于聚乙二醇化共聚物形成了可溶性复合物。然而，透射电子显微镜（TEM）显示，所得的含有聚乙二醇（PEG）的复合物没有很好地凝聚，易被核酸酶降解，因此不适合体内递送。聚乙二醇化共聚物的不良性质归因于过量的PEG。然而，NG47和NG49以确定的聚合物与共聚物比例以及总重复单元（RU）与核苷酸比例形成的聚合物共混物，自发形成了一系列具有理想性质的复合物。这些性质包括小尺寸和多分散性、高颗粒密度、低表面电荷以及抗核酸酶降解。单独用聚乙二醇化聚合物制备的复合物以及聚合物共混物的转染活性均降低。这归因于复合物表面电荷低，从而减少了与细胞膜的相互作用以及随后颗粒被细胞摄取的情况。
