While ultrasound has been widely used for medical imaging, it also has a variety of therapeutic applications. The technology could potentially facilitate the release of medication in precise locations for disorders and conditions that require drug treatment.
Ideally, a drug would be released only in specific regions of interest and at a high concentration, to maximize the benefits and minimize side effects. However, releasing a drug selectively in specific locations in the body, including the brain, has been challenging. Researchers have tackled the problem by designing ultrasound-sensitive nanoparticles that release a drug at the targeted site when activated by focused ultrasound.
Ideally, a drug would be released only in specific regions of interest and at a high concentration, to maximize the benefits and minimize side effects. However, releasing a drug selectively in specific locations in the body, including the brain, has been challenging. Researchers have tackled the problem by designing ultrasound-sensitive nanoparticles that release a drug at the targeted site when activated by focused ultrasound.
In a proof-of-concept study, University of Utah researchers tested whether this method could release a drug in a specific area of the brain of non-human primates. The results, published in the Journal of Controlled Release, showed that the ultrasound-sensitive nanoparticles released a substantial dose of the anesthetic propofol in specific deep brain regions. The treatment was found to be safe and effective, and the result was reversible.
“The main benefit of using ultrasound-sensitive nanoparticles is that they encapsulate the drug so that it has minimal interaction with the body, except where it’s released by focused ultrasound,” said Jan Kubanek, assistant professor of biomedical engineering and study’s corresponding author. “This could potentially allow us to treat under-regulated or malfunctioning circuits in the brain without exposing the entire brain and the body to drugs.”
Designing nanocarriers to deliver a drug payload
With funding from the National Institutes of Health, the researchers engineered new nanoparticles with three layers: an inner core made up of a contrast agent that responds to ultrasound activation, a second layer that encapsulates the drug, and an outer shell.
The design builds upon previous research in rodents that showed that nanoparticles can contain contrast agents that change from a liquid to gas upon interaction with high-frequency ultrasound waves. This approach facilitates a controlled release of the drug at a precise location.
However, a limitation of previous research was that the nanoparticles were unstable when they entered the bloodstream, which raised safety concerns. Kubanek’s team increased the stability of the nanoparticles by choosing a different contrast agent and adding an outer shell to the design. They also encapsulated the drug to prevent it from interacting with surrounding tissues and organs until it was activated by the ultrasound and released in the targeted brain region.
Continue reading at the National Institute of Biomedical Imaging and Bioengineering.