Direct emulsification of liquid perfluorobutane: an improved method to formulate superheated perfluorocarbon nanodroplets

This talk will describe a simple and robust method to produce perfluorobutane (PFB) nanodroplets by direct sonication, and will compare the properties of the resultant emulsions with those obtained with the current advocated microbubble condensation method. We found that nearly 100% of particles produced by direct emulsification of PFB liquid at low temperature are liquid PFB-filled, whereas the emulsion produced by microbubble condensation if the microbubbles are not washed, contains 2000 times more non-PFB filled than PFB-filled particles. Consequently, when such suspensions are used to target receptors, the abundance of non-PFB particles will act as competitive inhibitors, and when used to extravasate to reach extravascular targets, the lower count of PFB-filled particles will require larger doses decreasing efficacy and increasing side effects. Adopting this direct formulation could be a game changer for all applications when experimental outcome is dependent on nanodroplet concentration, stability, purity and size. As a result, this method should accelerate the translation of these ultrasound activatable nanodroplets to both image and potentially treat diseased tissues.