(194f) 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.