Drexel University researchers Steven Wrenn and Peter Lewin are trying to expand the possibilities of a drug delivery system that can penetrate the skin, called transdermal delivery. Microbubbles respond to ultrasound in two ways that are key to making the transdermal delivery. First, they can be pushed by ultrasound at an intensity gentle enough to keep the liposome intact. So, nesting the microbubbles inside a liposome is analogous to raising the sail on a boat to catch the wind. Secondly, when the intensity of the ultrasound is turned up a bit, it causes microbubbles to wobble like a spring and--if the intensity is high enough--pop. Wrenn's group has shown that these gas implosions in the vicinity of the liposome can rip it open, thus allowing disbursal of its contents. A significant advantage of their approach over current transdermal delivery methods is that it could easily be customized to work for a broad array of drugs and other biological products.
Credit: Drexel University