Development and characterization of cationic nanoemulsions as non-viral vectors for plasmid DNA delivery

Gene therapy is a promising approach to treat several diseases including cancer. Unfortunately, free nucleic acids are negatively charged and not stable in blood. Cationic drug delivery systems like cationic nanoemulsions (CNEs) are useful to improve the stability and delivery of nucleic acids like plasmid DNA (pDNA) by increasing the interaction between nucleic acids and negatively charged cell membrane. This study is focused on the development and characterization of two CNEs (CNE 1 and CNE 2) for the delivery of pDNA. The CNEs were prepared with microfluidization by investigating the homogenization duration of 1-10 minutes and the droplet size (DS), polydispersity index (PDI), zeta potential (ZP), complexation with pDNA and cytotoxicity on mouse fibroblast cells L929 were characterized. With increasing the microfluidization duration from 1 to 10 minutes, the DS and PDI decreased and the ZP increased for CNE 1, while for CNE 2 the ZP decreased too. Increasing the microfluidization duration does not lead to beneficial results, thus 1 minute seems to be sufficient for obtaining CNEs with appropriate properties. Both CNEs were able to form a complex in a ratio of 1 Al plasmid and 2 mu l CNE. The cytotoxicity studies for CNE 1 and its complex revealed that with increasing the applied dose the viability of the L929 cells decreased to 70%, while for CNE 2 and its complex the viability was reduced to 10%. Based on these results it can be stated that CNE 1 is more appropriate than CNE 2 for pDNA delivery.