As nanotechnology becomes ever more ubiquitous, researchers are using it to make medical diagnostics smaller, faster, and cheaper, in order to better diagnose diseases, learn more about inherited traits, and more.
But as sensors get smaller, measuring them becomes more difficult—there is always a tradeoff between how long any measurement takes to make and how precise it is. And when a signal is very weak, the tradeoff is especially big.
A team of researchers at Columbia Engineering, led by Electrical Engineering Professor Ken Shepard, together with colleagues at the University of Pennsylvania, has figured out a way to measure nanopores—tiny holes in a thin membrane that can detect single biological molecules such as DNA and proteins—with less error than can be achieved with commercial instruments. They have miniaturized the measurement by designing a custom integrated circuit using commercial semiconductor technology, building the nanopore measurement around the new amplifier chip. Their research will be published in the Advance Online Publication on Nature Methods's website on 18 March at 1400 (2pm) US Eastern time/ 1800 London time.
Nanopores are exciting scientists because they may lead to extremely low-cost and fast DNA sequencing. But the signals from nanopores are very weak, so it is critically important to measure them as cleanly as possible.
"We put a tiny amplifier chip directly into the liquid chamber next to the nanopore, and the signals are so clean that we can see single molecules passing through the pore in only one microsecond," says Jacob Rosenstein, a Ph.D. candidate in electrical engineering at Columbia Engineering and lead author of the paper. "Previously, scientists could only see molecules that stay in the pore for more than 10 microseconds."
Many single-molecule measurements are currently made using optical techniques, which use fluorescent molecules that emit photons at a particular wavelength. But, while fluorescence is very powerful, its major limitation is that each molecule usually produces only a few thousand photons per second. "This means you can't see anything that happens faster than a few milliseconds, because any image you could take would be too dim," explains Shepard, who is Rosenstein's advisor. "On the other hand, if you can use techniques that measure electrons or ions, you can get billions of signals per second. The problem is that for electronic measurements there is no equivalent to a fluorescent wavelength filter, so even though the signal comes through, it is often buried in background noise."
Shepard's group has been interested in single-molecule measurements for several years looking at a variety of novel transduction platforms. They began working with nanopore sensors after Marija Drndic, a professor of physics at the University of Pennsylvania, gave a seminar at Columbia Engineering in 2009. "We saw that nearly everybody else measures nanopores using classical electrophysiology amplifiers, which are mostly optimized for slower measurements," notes Shepard. "So we designed our own integrated circuit instead."
Rosenstein designed the new electronics and did much of the lab work. Drndic's group at the University of Pennsylvania fabricated the nanopores that the team then measured in their new system.
"While most groups are trying to slow down DNA, our approach is to build faster electronics," says Drndic. "We combined the most sensitive electronics with the most sensitive solid-state nanopores."
"It's very exciting to be able to make purely electronic measurements of single molecules," says Rosenstein. "The setup for nanopore measurements is very simple and portable. It doesn't require a complicated microscope or high powered instruments; it just requires attention to detail. You can easily imagine nanopore technology having a major impact on DNA sequencing and other medical applications within the next few years."Shepard's group is continuing to improve these techniques. "With a next-generation design," he says, "we may be able to get a further 10X improvement, and measure things that last only 100 nanoseconds. Our lab is also working with other electronic single-molecule techniques based on carbon nanotube transistors, which can leverage similar electronic circuits. This is an exciting time!"
Columbia University's Fu Foundation School of Engineering and Applied Science, founded in 1864, offers programs in nine departments to both undergraduate and graduate students. With facilities specifically designed and equipped to meet the laboratory and research needs of faculty and students, Columbia Engineering is home to NSF-NIH funded centers in genomic science, molecular nanostructures, materials science, and energy, as well as one of the world's leading programs in financial engineering. These interdisciplinary centers are leading the way in their respective fields while individual groups of engineers and scientists collaborate to solve some of modern society's more difficult challenges. http://www.engineering.columbia.edu/
Holly Evarts | EurekAlert!
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences