Ionization Behavior of Amino Lipids for siRNA Delivery: Determination of Ionization Constants, SAR, and the Impact of Lipid pKa on Cationic Lipid-Biomembrane Interactions
Ionization Behavior of Amino Lipids for siRNA Delivery: Determination of Ionization Constants, SAR, and the Impact of Lipid pKa on Cationic Lipid-Biomembrane Interactions
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DOI：
10.1021/la104590k
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发表时间：
2011-03-01
期刊：
影响因子：
3.9
通讯作者：
Crocker, Louis S.
中科院分区：
文献类型：
--
作者：
Zhang, Jingtao;Fan, Haihong;Crocker, Louis S.
可离子化的氨基脂质正被追求作为用于递送小干扰RNA（siRNA）治疗剂的一类重要材料，并且正在进行研究以阐明这些脂质的结构-活性关系（SAR）。由于脂质离子化对脂质的组装和性能的强烈影响，阳离子脂质头基的plc是感兴趣的关键理化性质之一。本研究的重点是开发允许快速测定可电离氨基脂质的相关pK（a）的方法。研究了两种不同的方法：（1）溶解在中性表面活性剂胶束中的氨基脂质的电位滴定;和（2）荧光染料对由氨基脂质配制的阳离子脂质体的pH依赖性分配。使用这里开发的方法，具有不同的头基的阳离子脂质的pK（a）值进行了测量，发现显着低于计算值。还发现脂质-脂质相互作用对脂质的pK（a）值具有强烈影响。使用阳离子脂质对模型生物膜的裂解来评估脂质pK（a）对阳离子脂质与细胞膜之间的相互作用的影响。结果表明，阳离子脂质与生物膜的相互作用强烈地依赖于脂质pK（a）和溶液pH，当氨基脂质带高电荷时，这种相互作用更强。基于这些结果，提出了用于siRNA递送的可电离氨基脂质的最佳pK（a）范围的存在。本文报道的pK（a）方法可用于支持用于siRNA递送的阳离子脂质的SAR筛选，并且通过研究pK（a）对阳离子脂质与细胞膜之间的相互作用的影响所揭示的信息将显著有助于设计更有效的siRNA递送载体。
Ionizable amino lipids are being pursued as an important class of materials for delivering small interfering RNA (siRNA) therapeutics, and research is being conducted to elucidate the structure-activity relationships (SA R) of these lipids. The plc of cationic lipid headgroups is one of the critical physiochemical properties of interest due to the strong impact of lipid ionization on the assembly and performance of these lipids. This research focused on developing approaches that permit the rapid determination of the relevant pK(a) of the ionizable amino lipids. Two distinct approaches were investigated: (1) potentiometric titration of amino lipids dissolved in neutral surfactant micelles; and (2) pH-dependent partitioning of a fluorescent dye to cationic liposomes formulated from amino lipids. Using the approaches developed here, the pK(a) values of cationic lipids with distinct headgroups were measured and found to be significantly lower than calculated values. It was also found that lipid-lipid interaction has a strong impact on the pK(a) values of lipids. Lysis of model biomembranes by cationic lipids was used to evaluate the impact of lipid pK(a) on the interaction between cationic lipids and cell membranes. It was found that cationic lipid-biomembrane interaction depends strongly on lipid pK(a) and solution pH, and this interaction is much stronger when amino lipids are highly charged. The presence of an optimal pK(a) range of ionizable amino lipids for si RNA delivery was suggested based on these results. The pK(a) methods reported here can be used to support the SAR screen of cationic lipids for siRNA delivery, and the information revealed through studying the impact of pK(a) on the interaction between cationic lipids and cell membranes will contribute significantly to the design of more efficient siRNA delivery vehicles.