In this work, a series of linear-dendritic poly(ethylene glycol) (PEG) lipids (PEG-GnCm) were synthesized through a strategy using sequential aza- and sulfa-Michael addition reactions. The effect of modulating the hydrophobic domain of linear-dendritic PEG lipids was systematically investigated for in vitro and in vivo small RNA delivery as the surface-stabilizing component of 5A2-SC8 dendrimer lipid-based nanoparticles (DLNPs). The lipid alkyl lengths (C8, C12, and C16) and dendrimer generations (G1, G2, and G3) were altered to create PEG-GnCm with different physical properties and anchoring potential. The tail chemical structure of PEG-GnCm did not affect the formulation of 5A2-SC8 DLNPs, including the nanoparticle size, RNA encapsulation, and stability. However, the tail chemical structure did dramatically affect the RNA delivery efficacy of the formed 5A2-SC8 DLNPs with different PEG-GnCm. First-generation PEG lipids (PEG-G1C8, PEG-G1C12, and PEG-G1C16) and a second-generation PEG lipid (PEG-G2C8) formed 5A2-SC8 DLNPs that could deliver siRNAs effectively in vitro and in vivo. 5A2-SC8 DLNPs formulated with second-generation PEG lipids (PEG-G2C12 and PEG-G2C16) and all three third-generation PEG lipids (PEG-G3C8, PEG-G3C12, and PEG-G3C16) lost the ability to deliver siRNA effectively in vitro and in vivo. Overall, we determined that the hydrophobic domain chemical structure of linear-dendritic poly(ethylene glycol) lipids affected the RNA delivery of DLNPs by impacting the escape of 5A2-SC8 DLNPs from endosomes at early cell incubation times, thereby indicating how PEG lipid anchoring and chemical structure can modulate in vitro and in vivo siRNA delivery efficacies.

中文翻译：

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线性树突状聚（乙二醇）脂质的疏水域结构影响脂质纳米颗粒的RNA传递。

在这项工作中，一系列的线性树突状聚（乙二醇）（PEG）脂质（PEG-GnCm）通过使用连续的氮杂和磺胺-迈克尔加成反应的策略合成。对于在体外和体内作为5A2-SC8树枝状大分子脂质纳米颗粒（DLNPs）的表面稳定成分的小RNA递送，系统地研究了调节线性树枝状PEG脂质疏水域的作用。改变脂质烷基的长度（C8，C12和C16）和树状聚合物世代（G1，G2和G3）以创建具有不同物理性质和锚定潜力的PEG-GnCm。PEG-GnCm的尾部化学结构不影响5A2-SC8 DLNP的配方，包括纳米粒径，RNA包封和稳定性。然而，尾部的化学结构确实极大地影响了形成的具有不同PEG-GnCm的5A2-SC8 DLNP的RNA传递功效。第一代PEG脂质（PEG-G1C8，PEG-G1C12和PEG-G1C16）和第二代PEG脂质（PEG-G2C8）形成了5A2-SC8 DLNP，可以在体内外有效地递送siRNA。用第二代PEG脂质（PEG-G2C12和PEG-G2C16）和所有三种第三代PEG脂质（PEG-G3C8，PEG-G3C12和PEG-G3C16）配制的5A2-SC8 DLNP失去了有效递送siRNA的能力体外和体内。总体而言，我们确定了线性树突状聚（乙二醇）脂质的疏水域化学结构会通过影响5A2-SC8 DLNP在早期细胞温育时从内体逃逸而影响DLNP的RNA传递，