Lipoplexes size/surface charge

The molar ratio of cationic liposome to nucleic acid determines the proportion of electrostatic neutralization, which reflects the entire surface charge and the size of resulting lipoplexes (13). Therefore, lipoplex formation should be affected by experimental variables such as nucleic acid/cationic liposome concentration, time and medium for the complexation, the number and/or order of addition steps, and the presence of serum during lipoplex formation. In this section, we will present instructions to form lipoplexes and discuss the most important aspects to be considered in siRNA- or pDNA-lipoplex formation. 

Among non-viral vectors, the lipoplex and polyplex systems [69,70], in which cationic Hpids and polycations, respectively, associate with DNA through an electrostatic interaction, are most widely studied for both in vitro and in vivo transfection. Their assets are that they can carry various size ranges of DNA, ease in manufacturing and mass production, a variety of chemical designs with smart fimctions, and their surface properties can be readily controlled by changing the charge ratio between the cationic polymer and DNA. 

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