Opimization of DNA entrapment in pH-sensitive liposomes

The pH-sensitive liposomes commonly used for DNA delivery, DOPE:CHOL:OA (4:4:2), upon further investigation, were found to be very inefficient in their ability to entrap plasmid DNA. This was a result of both the liposome composition and the size of the plasmid.

We have developed another liposome which maintains the pHsensitive characteristic of the previous composition but greatly enhances the DNA entrapment. These liposomes, composed of DOPE:DOSG (7:3), show 50% content release at pH 5.3 and have been able to entrap up to 31% of the added plasmid DNA after the plasmid had been reduced in size by 600 base pairs. It is expected that further reductions in the plasmid size will enhance entrapment to an even greater extent.