Glodde Martin, Sirsi Shashank R, Lutz Gordon J
Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA 19102, USA.
Biomacromolecules. 2006 Jan;7(1):347-56. doi: 10.1021/bm050726t.
Inefficient delivery of antisense oligonucleotides (AOs) to target cell nuclei remains as the foremost limitation to their usefulness. Copolymers of cationic poly(ethylene imine) (PEI) and poly(ethylene glycol) (PEG) have been well-studied for delivery of plasmids. However, the properties of PEG-PEI-AO polyplexes have not been comprehensively investigated. Therefore, we synthesized a series of PEG-PEI copolymers and evaluated their physiochemical properties alone and when complexed with AO. The M(w) of PEG was found to be the main determinant of polyplex size, via its influence on particle aggregation. DLS measurements showed that when PEG5000 was grafted to PEI2K and PEI25K, polyplex diameters were extremely small (range 10-90 nm) with minimal aggregation. In contrast, when PEG550 was grafted to PEI2K and PEI25K, polyplexes appeared as much larger aggregates (approximately 250 nm). As expected, the surface charge (zeta potential) was higher for polyplexes containing PEI25K than those containing PEI2K, but decreased with increased levels of PEG grafting. Surprisingly, within the physiological range (pH 7.5-5), the buffering capacity of all copolymers was nearly equivalent to that of unsubstituted PEI2K or PEI25K, and was barely influenced by PEGylation. The stability of polyplexes was evaluated using a heparin polyanion competition assay. Unexpectedly, polyplexes containing PEI2K showed stability equal to or greater than that of PEI25K polyplexes. The level of PEG grafting also had a dramatic effect on polyplex stability. The relationships established between molecular formulations and polyplex size, aggregation, surface charge, and stability should provide a useful guide for future studies aimed at optimizing polymer-mediated AO delivery in cell and animal studies. A summary of the relationships between polyplex structures and recent studies of their transfection capacity is provided.
反义寡核苷酸（AO）向靶细胞核的低效递送仍然是其应用的首要限制。阳离子聚（乙烯亚胺）（PEI）和聚（乙二醇）（PEG）的共聚物在质粒递送方面已得到充分研究。然而，PEG-PEI-AO多聚体的性质尚未得到全面研究。因此，我们合成了一系列PEG-PEI共聚物，并单独以及与AO复合时评估了它们的物理化学性质。发现PEG的M（w）通过其对颗粒聚集的影响，是多聚体大小的主要决定因素。动态光散射（DLS）测量表明，当PEG5000接枝到PEI2K和PEI25K上时，多聚体直径极小（范围为10 - 90nm），聚集最小。相反，当PEG550接枝到PEI2K和PEI25K上时，多聚体呈现为大得多的聚集体（约250nm）。正如预期的那样，含有PEI25K的多聚体的表面电荷（ζ电位）高于含有PEI2K的多聚体，但随着PEG接枝水平的增加而降低。令人惊讶的是，在生理范围内（pH 7.5 - 5），所有共聚物的缓冲能力几乎与未取代的PEI2K或PEI25K相当，并且几乎不受聚乙二醇化的影响。使用肝素聚阴离子竞争试验评估了多聚体的稳定性。出乎意料的是，含有PEI2K的多聚体显示出与PEI25K多聚体相等或更高的稳定性。PEG接枝水平对多聚体稳定性也有显著影响。在分子配方与多聚体大小、聚集、表面电荷和稳定性之间建立的关系，应为未来旨在优化细胞和动物研究中聚合物介导的AO递送的研究提供有用的指导。提供了多聚体结构与其转染能力的近期研究之间关系的总结。
