When placed inside a high-frequency but low-strength magnetic field, the nanoparticles heat up, warming the lipids and making them undergo a transition from solid to liquid, which makes the layer more porous - just enough to let some of the drug molecules escape into the surrounding areas. Electron microscope image shows the actual liposome, the white blob at center, with its magnetic particles showing up in black at its center. These are like little bubbles of lipids, which naturally form a spherical double layer surrounding a water droplet. Rao came up with the idea of taking magnetic nanoparticles, which had already been shown to be capable of being heated by placing them in a magnetic field, and packing them into these spheres called liposomes. The hard part was finding materials that could be triggered to heat up by using a very weak magnetic field (about one-hundredth the strength of that used for MRI), in order to prevent damage to the drug or surrounding tissues, Rao says. Magnetic fields, which can easily penetrate through the body - as demonstrated by detailed internal images produced by magnetic resonance imaging, or MRI - were a natural choice. “And if we don’t want it to be invasive, we need to find a non-invasive way to trigger the release.” “We wanted a system that could deliver a drug with temporal precision, and could eventually target a particular location,” Anikeeva explains. The findings are reported today in the journal Nature Nanotechnology in a paper by MIT postdoc Siyuan Rao, Associate Professor Polina Anikeeva, and 14 others at MIT, Stanford University, Harvard University, and the Swiss Federal Institute of Technology in Zurich. The drug of choice is encapsulated within these bubbles, and can be released by applying a magnetic field to heat up the particles, allowing the drug to escape from the liposome and into the surrounding tissue. The new approach is based on the use of tiny magnetic particles enclosed within a tiny hollow bubble of lipids (fatty molecules) filled with water, known as a liposome. Now, researchers at the McGovern Institute at MIT and elsewhere have developed a system to deliver medical treatments that can be released at precise times, minimally-invasively, and that ultimately could also deliver those drugs to specifically targeted areas such as a specific group of neurons in the brain. Either way, it takes some time for them to reach their intended targets, and they also tend to spread out to other areas of the body. Most pharmaceuticals must either be ingested or injected into the body to do their work. Poitras Center for Psychiatric Disorders Research.Principal Research Scientists Open Principal Research Scientists.
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