Lipid Shell Composition Plays a Critical Role in the Stable Size Reduction of Perfluorocarbon Nanodroplets.

Perfluorocarbon nanodroplets (PFCnDs) are phase-change contrast agents that have the potential to enable extravascular contrast-enhanced ultrasound and photoacoustic (US/PA) imaging. Producing consistently small, monodisperse PFCnDs remains a challenge without resorting to technically challenging methods. We investigated the impact of variable shell composition on PFCnD size and US/PA image properties. Our results suggest that increasing the molar percentage of PEGylated lipid reduces the size and size variance of PFCnDs. Furthermore, our imaging studies revealed that nanodroplets with more PEGylated lipids produce increased US/PA signal compared with those with the standard formulation. Finally, we highlight the ability of this approach to facilitate US/PA imaging in a murine model of breast cancer. These data indicate that, through a facile synthesis process, it is possible to produce monodisperse, small-sized PFCnDs. Novel in their simplicity, these methods may promote the use of PFCnDs among a broader user base to study a variety of extravascular phenomena.