Poly(amidoamine) (PAMAM) dendrimers have been widely used as nucleic acid delivery vectors. To improve the transfection efficacy, ligands such as amino acid, peptide and lipid are conjugated to the periphery of dendrimers. However, the structures of these ligands are generally flexible, and few reports about rigid-ligand-modified dendrimers are reported. In this work, three novel PAMAM dendrimers (G₅-1, G₅-2 and G₅-3) modified with rigid naphthalimide were synthesized as nucleic acid delivery vectors. Magnetic resonance spectroscopy showed that the average numbers of naphthalimide molecules conjugated on the PAMAM periphery in compounds G₅-1, G₅-2 and G₅-3 are 8, 30 and 50, respectively. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay revealed good cytocompatibility of these vectors in multiple cell lines, including MG63, HeLa, HEK293 and MC3T3-E1 cells, with a cell survival rate of more than 90% in most cases. Among the three dendrimers, G₅-1 with fewer naphthalimide molecules showed stronger RNA binding ability than G₅-2 and G₅-3. G₅-1 also exhibited the best gene silencing efficacy at a dendrimer to miRNA weight ratio of 1:2 in MC3T3-E1 cells, which is much higher than the commercial transfection agent Lipofectamine 2000 tested under the same conditions. In addition, G₅-1 showed high transfection efficacy in plasmid DNA-mediated luciferase expression experiments. These results suggest that rigid ligand modification can be developed as a new strategy to design safe and highly efficient nucleic acid delivery vectors. © 2021 Society of Industrial Chemistry.

中文翻译：

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萘酰亚胺修饰的树枝状聚合物作为高效且低细胞毒性的核酸递送载体

聚（酰胺胺）（PAMAM）树枝状聚合物已被广泛用作核酸递送载体。为了提高转染效率，将氨基酸、肽和脂质等配体结合到树枝状聚合物的外围。然而，这些配体的结构通常是灵活的，关于刚性配体修饰的树枝状聚合物的报道很少。在这项工作中，合成了三种用刚性萘酰亚胺修饰的新型 PAMAM 树枝状聚合物（G ₅ -1、G ₅ -2和G ₅ -3）作为核酸递送载体。磁共振波谱显示化合物G ₅ -1 中PAMAM 外围共轭的萘二甲酰亚胺分子的平均数、G ₅ -2和G ₅ -3分别为8、30和50。3-(4,5-二甲基噻唑-2-基)-2,5-二苯基溴化四唑 (MTT) 测定显示这些载体在多种细胞系中具有良好的细胞相容性，包括 MG63、HeLa、HEK293 和 MC3T3-E1 细胞，具有大多数情况下细胞存活率超过90%。在三种树枝状聚合物中，萘酰亚胺分子较少的G ₅ -1表现出比G ₅ -2和G ₅ -3更强的RNA结合能力。G ₅ -1在 MC3T3-E1 细胞中，树状聚合物与 miRNA 重量比为 1:2 时也表现出最佳的基因沉默效果，这远高于在相同条件下测试的商业转染剂 Lipofectamine 2000。此外，G ₅ -1在质粒 DNA 介导的荧光素酶表达实验中显示出很高的转染效率。这些结果表明刚性配体修饰可以作为设计安全高效的核酸递送载体的新策略而开发。© 2021 工业化学学会。