Figure 2.

Various nanoparticles (not to scale) that may be used in ultrasound-enhanced drug and gene delivery. (a) Micelle (nonpolymeric) composed of amphiphilic surfactants. (b) Polymeric micelle composed of amphiphilic block copolymers. (c) Nanoemulsion consisting of a hydrophobic liquid core stabilized by surfactant. (d) Crystalline nanoparticles. (e) Amorphous polymeric nanoparticle. (f) Condensed ionic oligomers, such as DNA condensed with PEI or cationic lipids. (g) Single-walled liposome consisting of an amphiphilic bilayer surrounding an aqueous core. Reprinted with permission from [71].