Long-term Stability of Cationic Phytosphingosine Nanoemulsions as Delivery Systems for plasmid DNA

Abstract

The case of ready to use gene delivery systems like cationic nanoemulsions is not reflecting the truth. Thus, delivery systems for applicating genes like nucleic acids have to be prepared freshly before each application. This study is focused on the preparation and characterization of cationic nanoemulsions using phytosphingosine for plasmid DNA delivery. Repurposing of cationic agents guided us to phytosphingosine, previously used for enhanced interaction with negatively charged surfaces. It was reported that phytosphingosine may act anti-apoptotic, but without using it in an appropriate delivery system like nanoemulsions. This gap attracted our interest about preparing and characterizing long-term stable cationic nanoemulsions and their cytotoxic effects on MDA-MB-231 and MCF-7 breast cancer cells using phytosphingosine. The cationic nanoemulsions 1, 2, and 3 were prepared and characterized in terms of droplet size, polydispersity index, and zeta potential, long-term stability after storage at 25 and 40 °C, complexation with pDNA, release and cytotoxicity on MDA-MB-231 and MCF-7 cells. The CNEs showed appropriate properties like a small droplet size (+30 mV). Unfortunately, each cationic nanoemulsion showed some disadvantages. Cationic nanoemulsion 1 decreased the viability of cancer cells to only 25 %. Phase separation was observed for cationic nanoemulsion 2 after storage of six months at 40 °C. And cationic nanoemulsion 3 was not able to form a complex with pDNA.
 However, cationic nanoemulsion 1 is more appropriate than the other cationic nanoemulsions for delivering pDNA.