In this work, highly osmotic oxidized sucrose-crosslinked polyethylenimine (SP2K) polymers were developed for gene delivery systems, and the transfection mechanism is examined. First, periodate-oxidized sucrose and polyethylenimine 2K (PEI2K) were crosslinked with various feed ratios via reductive amination. The synthesis was confirmed by ¹H NMR and FTIR. The synthesized SP2K polymers could form positively charged (~40 mV zeta-potential) and nano-sized (150–200 nm) spherical polyplexes with plasmid DNA (pDNA). They showed lower cytotoxicity than PEI25K but concentration-dependent cytotoxicity. Among them, SP2K7 and SP2K10 showed higher transfection efficiency than PEI25K in both serum and serum-free conditions, revealing the good serum stability. It was found that SP2K polymers possessed high osmolality and endosome buffering capacity. The transfection experiments with cellular uptake inhibitors suggest that the transfection of SP2K polymers would progress by multiple pathways, including caveolae-mediated endocytosis. It was also thought that caveolae-mediated endocytosis of SP2K polyplexes would be facilitated through cyclooxygenase-2 (COX-2) expression induced by high osmotic pressure of SP2K polymers. Confocal microscopy results also supported that SP2K polyplexes would be internalized into cells via multiple pathways and escape endosomes efficiently via high osmolality and endosome buffering capacity. These results demonstrate the potential of SP2K polymers for gene delivery systems.

中文翻译：

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用于基因传递系统的高渗透氧化蔗糖交联聚乙烯亚胺

在这项工作中，开发了高度渗透性的氧化蔗糖交联的聚乙烯亚胺（SP2K）聚合物用于基因传递系统，并研究了转染机制。首先，高碘酸盐氧化的蔗糖和聚乙烯亚胺2K（PEI2K）通过还原胺化以各种进料比交联。合成通过¹确认1 H NMR和FTIR。合成的SP2K聚合物可与质粒DNA（pDNA）形成带正电（〜40 mVζ电位）和纳米级（150-200 nm）球形多链体。他们显示出比PEI25K更低的细胞毒性，但浓度依赖性细胞毒性。其中，在血清和无血清条件下，SP2K7和SP2K10的转染效率均高于PEI25K，显示出良好的血清稳定性。发现SP2K聚合物具有高渗透压和内体缓冲能力。用细胞摄取抑制剂进行的转染实验表明，SP2K聚合物的转染将通过多种途径进行，包括小窝介导的内吞作用。还认为通过SP2K聚合物的高渗透压诱导的环氧合酶-2（COX-2）表达将促进SP2K多聚体的小窝介导的内吞作用。共聚焦显微镜结果还支持SP2K多聚体将通过多种途径内化到细胞中，并通过高渗透压和内体缓冲能力有效地逃逸内体。这些结果证明了SP2K聚合物在基因递送系统中的潜力。