Scientists at Duke University and Daegu Gyeongbuk Institute of Science and Technology (DGIST) in Korea say they have developed a chip-like device that could be scaled up to sort and store hundreds of thousands of individual living cells in a matter of minutes. The team expects that the cell-sorting system will revolutionize research by allowing the fast, efficient control and separation of individual cells that could then be studied in vast numbers.
"Most experiments grind up a bunch of cells and analyze genetic activity by averaging the population of an entire tissue rather than looking at the differences between single cells within that population," said Benjamin Yellen, Ph.D., an associate professor of mechanical engineering and materials science at Duke's Pratt School of Engineering. "That's like taking the eye color of everyone in a room and finding that the average color is grey, when not a single person in the room has grey eyes. You need to be able to study individual cells to understand and appreciate small but significant differences in a similar population."
Dr. Yellen and his collaborator, Cheol Gi Kim, Ph.D., of DGIST, who reported the team’s work ("Magnetophoretic circuits for digital control of single particles and cells") in Nature Communications, printed thin electromagnetic components like those found on microchips onto a slide. These patterns create magnetic tracks and elements like switches, transistors, and diodes that guide magnetic beads and single cells tagged with magnetic nanoparticles through a thin liquid film.
Like a series of small conveyer belts, localized rotating magnetic fields move the beads and cells along specific directions etched into a track, while built-in switches direct traffic to storage sites on the chip. The result is an integrated circuit that controls small magnetic objects much like the way electrons are controlled on computer chips.
In the study, the engineers demonstrated a 3-by-3 grid of compartments that allow magnetic beads to enter but not leave. By tagging cells with magnetic particles and directing them to different compartments, the cells can be separated, sorted, stored, studied, and retrieved. The researchers now plan to demonstrate a larger grid of 8-by-8 or 16-by-16 compartments with cells, and then to scale it up to hundreds of thousands of compartments. If successful, their technology would lend itself well to manufacturing, giving scientists around the world access to single-cell experimentation.
"Our idea is a simple one," said Dr. Kim. "Because it is a system similar to electronics and is based on the same technology, it would be easy to fabricate. That makes the system relevant to commercialization. There's another technique we need to do as a follow-up before we get to actual biological applications."