Three years ago Arthur Ashkin received the Nobel Prize for the invention of optical tweezers that use light in the form of a high-power laser beam to capture and manipulate particles. Although optical tweezers were developed decades ago, they still make large breakthroughs and are widely used today to study biological systems.
Optical tweezers, however, have shortcomings. The prolonged interaction with the laser beam can change molecules and particles or be damaged by excessive heat.
Researchers at the University of Texas at Austin have developed a new version of optical tweezer technology that addresses this problem.
The breakthrough that avoids this overheating problem arises from the combination of two concepts: the use of a substrate made of materials that are cooled when exposed to light (in this case a laser); and a concept called thermophoresis, a phenomenon in which mobile particles generally gravitate into a cooler environment.
The cooler materials attract particles, making them easier to isolate while protecting them from overheating. By solving the heat problem, optical tweezers could become more widely used to study biomolecules, DNA, diseases and more.
“Optical tweezers have many advantages, but they are limited because when the light catches objects, they heat up,” says Yuebing Zheng, the corresponding author of a new article published in. has been published Scientific advances and Associate Professor in the Walker Department of Mechanical Engineering. “Our tool addresses this critical challenge; Instead of heating the enclosed objects, we let them regulate to a lower temperature. “
Optical tweezers do the same thing as regular tweezers – pick up small objects and manipulate them. Optical tweezers, however, work on a much smaller scale and use light to capture and move objects.
The analysis of DNA is a common application of optical tweezers. However, this requires nano-sized glass beads to be attached to the particles. In order to move the particles, the laser is aimed at the beads, not at the particles themselves, as the heat from the light would damage the DNA.
“If you are forced to add more steps to the process, you add to the uncertainty because you have now introduced something else into the biological system that could affect it,” Zheng said.
This new and improved version of the optical tweezers eliminates the need for these additional steps.
The team’s next steps include developing autonomous control systems that make it easier to use for those without special training, and expand the tweezers’ capabilities to handle biological fluids such as blood and urine. And they’re working to commercialize the discovery.
Zheng and his team have a lot of variety in their research, but everything revolves around light and how it interacts with materials. Because of this focus on light, he closely followed and used optical tweezers in his research. The researchers were familiar with thermophoresis and hoped to trigger it with cooler materials that would actually pull particles towards the laser to make analysis easier.
This research was supported by grants from the National Institute of General Medical Sciences, the National Institutes of Health, and the National Science Foundation. Other authors include Jingang Li and Zhihan Chen of the UT’s Texas Materials Institute; Yaoran Liu from the Faculty of Electrical and Computer Engineering; Pavana Siddhartha Kollipara from the Walker Department of Mechanical Engineering; and Yichao Feng and Zhenglong Zhang from the School of Physics and Information at Shaanxi Normal University in China.
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