Institute of Immunology, Research and Development Department, Zagreb, Croatia.
Int J Nanomedicine. 2012;7:393-401. doi: 10.2147/IJN.S27471. Epub 2012 Jan 25.
Physicochemical characteristics of liposome/DNA complexes influence transfection efficiency and affect each other in a very intricate way. The result of this is discrepancies in conclusions drawn about the individual influence of each one.
Aiming to elucidate the influence of liposome/DNA charge ratio and size on transfection efficiency and on each other, we used liposome/DNA complexes with charge ratio (+/-) in the range of 1-50 and extruded through membranes of 400, 200, and 100 nm. Plasmid DNA encoding green fluorescent protein was used to measure transfection efficiency by flow cytometry. Sizes of liposome/DNA complexes were measured by dynamic light scattering.
Liposome size was reduced after extrusion but this was mainly driven by the charge ratio and not by the size of the membrane pores. Reduction of complex size at each charge ratio positively correlated with transfection efficiency. When the size of the complexes was approximately constant, increasing the charge ratio was found to promote transfection efficiency. Cationic lipid N-(1-(2,3-dioleoyloxy)propyl)N,N,N trimethylammonium chloride was used for modulation of positive charge and a cytotoxicity test showed that increasing its amount increases cytotoxicity.
It can be concluded that charge ratio dictates the size of the complex whereas overall size reduction and higher charge ratios promote transfection efficiency in vitro.
脂质体/DNA 复合物的理化特性影响转染效率，并以非常复杂的方式相互影响。其结果是，对于每个因素的单独影响的结论存在差异。
为了阐明脂质体/DNA 电荷量比和大小对转染效率和彼此的影响，我们使用电荷量比（+/-）在 1-50 范围内的脂质体/DNA 复合物，并通过 400nm、200nm 和 100nm 的膜挤出。使用编码绿色荧光蛋白的质粒 DNA 通过流式细胞术测量转染效率。通过动态光散射测量脂质体/DNA 复合物的大小。
挤出后脂质体的大小减小，但这主要是由电荷量比驱动的，而不是由膜孔的大小驱动的。在每个电荷量比下，复合物尺寸的减小与转染效率呈正相关。当复合物的尺寸大致相同时，增加电荷量比被发现可以提高转染效率。N-（1-（2,3-二油酰氧基）丙基）N,N,N-三甲基氯化铵被用于调节正电荷，细胞毒性试验表明，增加其用量会增加细胞毒性。
可以得出结论，电荷量比决定了复合物的大小，而总体尺寸减小和更高的电荷量比促进了体外的转染效率。
