Brain 'probe' delivers drugs with minimal damage
17 July 2015
Researchers have created a remotely controlled tissue implant that allows neuroscientists to inject drugs and shine light on neurons deep inside the brain.
"It unplugs a world of possibilities for scientists to learn how brain circuits work in a more natural setting," says Michael Bruchas, an associate professor of anaesthesiology and neurobiology at Washington University School of Medicine and a senior author of the study.
The Bruchas lab studies circuits that control a variety of disorders including stress, depression, addiction, and pain. Typically, scientists who study these circuits have to choose between injecting drugs through bulky metal tubes and delivering lights through fiber optic cables. Both options require surgery that can damage parts of the brain.
To address these issues, Jae-Woong Jeong, a bioengineer formerly at the University of Illinois at Urbana-Champaign, worked with Jordan McCall, a graduate student in the Bruchas lab, to construct a remotely controlled, optofluidic implant. The device is made from soft materials that are a tenth the diameter of a human hair and can simultaneously deliver drugs and light.
"We used powerful nano-manufacturing strategies to fabricate an implant that lets us penetrate deep inside the brain with minimal damage," says Professor John Rogers of the University of Illinois at Urbana-Champaign and a senior author of the paper. "Ultra-miniaturised devices like this have tremendous potential for science and medicine."
With a thickness of 80 micrometres and a width of 500 micrometres, the optofluidic implant is thinner than the metal tubes, or cannulas, scientists typically use to inject drugs. When the scientists compared the implant with a typical cannula they found that the former damaged and displaced much less brain tissue.
The researchers fabricated the implant using semiconductor manufacturing techniques. It has room for up to four drugs and has four microscale inorganic light-emitting diodes. They installed an expandable material at the bottom of the drug reservoirs to control delivery. When the temperature of an electric heater beneath the reservoir rises, the bottom rapidly expands and pushes the drug into the target area.