Effect of Ultrasound and Emulsion On Release of Paclitaxel From Eliposomes

 

Our lab has developed a nano sized liposomal drug that can be burst by applying ultrasound. These new carriers do not require nearby gas bubbles for ultrasonic activation because they contain a nano emulsion droplet inside that can change phase from liquid to gas upon application of ultrasound. This drug carrier is called an eLiposome, which is a liposome bilayer containing emulsion droplets. The emulsion droplets are made of a perfluorocarbon (PFCs) liquid with high vapor pressure such as perfluoropentane. While applying ultrasound, the local pressure drops below the high vapor pressure that induces the formation and expansion of a vapor phase. The expansion ruptures the liposome, which releases the drug or genes locally. One of the advantages of emulsion droplets compared to microbubbles is that they can be made very small scale so eLiposomes can extravasate via the EPR effect.

This study revealed the 2 of essential components of the eLiposome delivery vehicle. Internal emulsions in combination with ultrasound were found to be necessary to obtain release of paclitaxel (PTX). With neither ultrasound nor internal PFC5 emulsion, delivery was very low. Cell viability was measured to determine the effect of emulation and ultrasound on release of PTX from eLiposomes.

Nanocarriers containing PTX were added to HeLa cells and 20 kHz ultrasound was applied. After application of ultrasound cells were incubated for 6, 24, and 48 hours and then viable cells were counted. Fig. 1 shows the effect of ultrasound on cell viability.