Figure 7.

Nesting Microbubbles within PLA Microcapsules: A) Electron micrograph of a typical batch of PLA microcapsules. The size is easily varied via homogenization speed; clinical applications require diameters smaller than 10 microns for passage through capillaries. B) Cartoon representation showing multiple microbubbles inside the aqueous core of a single PLA microcapsule. Each microbubble is coated with a phospholipid monolayer, and the microbubbles are nested inside a single PLA shell that serves to limit microbubble expansion and thus inhibit inertial cavitation. C) A fluorescent micrograph showing a large population of rhodamine-labeled microbubbles contained within a PLA microcapsule. The PLA microcapsule in panel C was made for visualization purposes and is sufficiently large (~50 μm diameter) that individual microbubbles, each approximately 1-2 microns in diameter, appear as bright dots. Adapted from ⁸¹ and ⁴³