What the research is about
What if a tiny droplet could swim like a jellyfish when exposed to light-and even carry cargo along the way? A research team led by Professor Masahiro Takinoue and Specially Appointed Assistant Professor Hirotake Udono at Institute of Science Tokyo (Science Tokyo) has made this possible using DNA.
Most people think of DNA as the molecule that carries genetic information. However, DNA can also be designed to have a wide range of structures and functions. In recent years, researchers have discovered that DNA molecules can gather together and form soft, droplet-like structures. These droplets are used as model systems to study a biological phenomenon known as phase separation.
Phase separation occurs when specific molecules inside a cell gather together to form liquid-like droplets, much like how oil and water naturally separate in salad dressing. Scientists believe that phase separation plays an important role in how cells organize their internal activities. Researchers are also investigating how the physical states of these droplets-such as being more liquid-like or more solid-like-may be linked to diseases.
Previous studies showed that DNA droplets could change shape or switch between different states in response to temperature or light. Researchers hoped that these changes could eventually be used to generate fluid flows, allowing the droplets to act like tiny pumps or motors that transport and mix materials inside spaces as small as a cell. However, no one had succeeded in converting these state changes into controlled motion or transport.
To overcome this challenge, the Science Tokyo team incorporated light-responsive molecules into DNA droplets. As a result, they succeeded in using light to switch the properties of the droplets and convert those changes into fluid flow and mechanical motion.
Why this matters
The most important achievement of this study is that it demonstrates, for the first time, that changes in the state of DNA droplets can be transformed into actual motion and mechanical work.
By switching between ultraviolet and visible light, the researchers were able to make DNA droplets spread out, gather together, reassemble, and even fold objects. They also discovered that illuminating only part of a droplet caused it to move in a specific direction, producing a motion that looked like swimming. Using this motion, the team successfully transported other particles as cargo.
Previous studies could change the shape or state of DNA droplets, but they could not use those changes to move surrounding fluids or transport materials. This work goes a step further by converting molecular-scale changes into micrometer-scale flows and motion that perform real physical work.
The researchers also found that the speed at which light is switched on and off affects the type of motion produced. This discovery could provide a new strategy for controlling microscopic fluid flows and material transport using light.
What’s next
A key advantage of this technology is that it can move liquids and materials in tiny spaces using only light, without requiring pumps, channels, or other mechanical devices. In the future, it could be used to transport molecules inside artificial cells, drive miniature soft robots, mix liquids inside microscopic reaction chambers, or deliver drugs to specific locations.
Because different functions can be programmed by designing DNA sequences and combining them with light-responsive molecules, this technology may eventually lead to programmable microfluidic systems with applications in medicine, biotechnology, and materials science.
Comment from the researcher
DNA is widely known as the blueprint of life, but it also has enormous potential as a programmable biomolecule. In this study, we demonstrated that changes in the state of DNA dropetscan be used to generate fluid flow and motion. Moving forward, we aim to develop intelligent fluidic robots that can operate inside and around living cells, artificial cells, and microrobots.
(Hirotake Udono, Specially Appointed Assistant Professor, Laboratory for Chemistry and Life Science, Institute of Integrated Research, Institute of Science Tokyo)
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