Designing pH-sensitive gemini nanoparticles for non-viral gene delivery into keratinocytes
作者:McDonald Donkuru、Shawn D. Wettig、Ronald E. Verrall、Ildiko Badea、Marianna Foldvari
DOI:10.1039/c2jm15719e
日期:——
This study aimed to develop a more effective non-viral gene delivery system for keratinocyte transfection. To this end, gemini nanoparticles were formulated from plasmid DNA, the lipid DOPE (dioleoylphosphatidylethanolamine) and surfactants, where the surfactant components are novel pH-sensitive gemini surfactant derivatives based on the m-7-m (alkyl chain–spacer–alkyl chain, m-s-m) unsubstituted base structure. The resultant 1,9-bis(alkyl)-1,1,9,9-tetramethyl-5-amino-1,9-nonanediammonium dibromide surfactants, m-7NH-m, where m = 12, 16, 18 and 18:1, are hypothesized to stage endosomal release of DNA. The m = 18:1 chain, i.e., mono-unsaturated oleyl chain, is an alkenyl chain analogue for comparison with the saturated m = 18 alkyl chain based on the m-7NH-m frame. Analytical and physicochemical characterization of the gemini surfactants included purity, aggregation properties under pH 2.5–10.5, critical micellar concentration and pKa. Gemini nanoparticles were characterized by dynamic light scattering, zeta potential, small-angle X-ray scattering and transmission electron microscopic studies. Keratinocyte transfection efficiency and cytotoxicity were evaluated using the luciferase reporter assay and luminescent cell viability assay, respectively. Gemini nanoparticles formulated from the m-7NH-m gemini surfactants at a surfactant:DNA charge ratio (ρ±) 10:1 showed higher transfection efficiency compared to the unsubstituted compounds (m-7-m, m-3-m series) (p < 0.01). Transfection efficiency increased with increasing tail length, i.e., m = 12 < m = 16 < m = 18 (p > 0.01), although the difference between m = 16 and m = 18 was insignificant. Morphological studies of the nanoparticles by transmission electron microscopy showed fusogenic changes at pH = 5. The incorporation of a pH-active amine group within the spacer of the gemini surfactants significantly enhanced transfection efficiency in keratinocytes. This may be attributed to optimal interactions between DNA phosphate groups and the m-7NH-m gemini surfactants owing to their –NH– groups, trimethylene spacing between nitrogen centers and the acidic pH-induced polymorphic changes, leading to endosomal release of plasmid. Such results highlight the amino-substituted gemini surfactants as potential components for developing non-viral nanoparticles with enhanced gene delivery for targeting diseases affecting the skin.
本研究旨在开发一种更有效的非病毒基因传递系统,用于角质形成细胞的转染。为此,采用质粒DNA、脂质DOPE(双油酸磷脂酰乙醇胺)和表面活性剂配制了双子纳米颗粒,其中表面活性剂成分是基于m-7-m(烷基链–间隔–烷基链,m-s-m)未取代基础结构的新型pH敏感双子表面活性剂衍生物。所得到的1,9-双(烷基)-1,1,9,9-四甲基-5-氨基-1,9-壬二胺二溴化物表面活性剂m-7NH-m,其中m = 12、16、18和18:1,假设在内吞体中诱导DNA的释放。m = 18:1链,即单不饱和油酸链,是与基于m-7NH-m框架的饱和m = 18烷基链进行比较的烯烃链类似物。对双子表面活性剂的分析和物理化学表征包括纯度、在pH 2.5-10.5下的聚集特性、临界胶束浓度和pKa。双子纳米颗粒通过动态光散射、ζ电位、小角X射线散射和透射电子显微镜研究进行了表征。使用荧光素酶报告基因检测和发光细胞活力检测评估角质形成细胞的转染效率和细胞毒性。从m-7NH-m双子表面活性剂配制的双子纳米颗粒,在表面活性剂:DNA电荷比(ρ±)为10:1时,与未取代化合物(m-7-m, m-3-m系列)相比,显示出更高的转染效率(p < 0.01)。转染效率随着尾部长度的增加而增加,即m = 12 < m = 16 < m = 18(p > 0.01),尽管m = 16与m = 18之间的差异不显著。透射电子显微镜对纳米颗粒的形态学研究显示在pH = 5时出现了融合变化。将pH活性氨基团纳入双子表面活性剂的间隔中显著提升了角质形成细胞的转染效率。这可能归因于DNA磷酸基团与m-7NH-m双子表面活性剂之间的最佳相互作用,这得益于它们的–NH–基团、氮中心之间的三亚甲基间隔以及酸性pH诱导的多形态变化,从而导致质粒在内吞体中的释放。这些结果凸显了氨基取代的双子表面活性剂作为开发具有增强基因传递的非病毒纳米颗粒的潜在组成部分,以针对影响皮肤的疾病。