A Nanotube-Based COVID-19 Test

​​Recent news in nanoscience highlights the enormous scope of this exciting field. We start with a new nanotube-based diagnostic test that can tell if you have—or ever had—the coronavirus. Then we look at a magnetic sensor that captures, records, and remembers magnetic waves—and it is only 11 atoms in size. Next we’ll consider why some identical organisms adapt better to change than others and honor a researcher who looks at quantum behavior in large materials. Finally—for all of you who saw videos of people walking on water mixed with cornstarch—we discuss ways to sink those walkers.

Nanotubes power quick COVID-19 test

Today, people who think they have COVID-19 take one test while those who think they may have had it before must take another. So, biotech company Nanomix developed a solution to both their needs: a nanotube-based test that takes 15 minutes to detect active infections and previous exposure to coronavirus. The company just received a $570,000 grant to commercialize the technology, which uses carbon nanotubes detect biomarkers—antibodies, antigens, and other proteins—electronically, rather than optically like most systems. The technology is based on research done by Alex Zettl, a member of the Kavli Energy NanoScience Institute at Berkeley and his collaborator, Marvin Cohen. Twenty years ago, they demonstrated that carbon nanotubes with walls only an atom or two thick were ultrasensitive to oxygen. Zettl’s lab went on to show that the same nanotubes could detect proteins and carbohydrates in individual cells. The two researchers spun off Nanomix to commercialize the technology.

An 11-atom magnetic sensor

Researchers have built an 11-atom sensor that catches and records atom-sized magnetic waves. Small though it is, the device includes an antenna, readout capability, reset button, and memory. Right now, the sensor, built by a team led by Sander Otte, a member of the Kavli Institute of Nanoscience at Delft University of Technology, is being used to study spintronics, a possible approach to quantum computing that uses magnetic signals from electrons rather than electricity to communicate data. Yet understanding those magnetic signals is hard: Not only do they vanish in nanoseconds, but thanks to the strange laws of quantum mechanics, they can travel in multiple directions at once. At 11 atoms, this sensor small and fast enough to penetrate such quantum weirdness—and take notes.

Random DNA expression

Genetics is not destiny. In fact, there is a whole field, epigenetics, devoted to explaining why, in genetically identical twins, some genes turn on and make proteins while others do not. Environment is one reason. But a recent study of baker’s yeast found an additional reason as well—random variation of proteins. Werner Daalman, a PhD-candidate in the lab of Kavli Institute of Nanoscience at Delft member Liedewij Laan, started off growing genetically identical yeast. Given the same environment, you would think they would all grow in the same direction. But that did not happen. Instead, random differences in the amount growth proteins determined which direction the yeast grew. According to Daalman, such random variations in proteins may explain why simple organisms can adapt rapidly to environmental changes.

Massive quantum behavior

When most folks hear the word, “quantum,” they think of something tiny. That is because quantum behavior is unnoticeable in everyday objects, but clearly visible in things like atoms, electrons, and photons—if you happen to have a laboratory full of expensive scientific instruments. Yet quantum properties do indeed occur in larger materials, and J.C. Seamus Davis, a member of the Kavli Institute at Cornell for Nanoscale Science has received a five-year, $1.6 million grant to study them. Davis’ specialty is what he calls the quantum physics of large-scale quantum objects. He focuses on superconductors, which carry current without resistance; superfluids, which have no viscosity and if stirred will form a vortex that lasts indefinitely; and supersolids (such as Bose-Einstein condensates), which are orderly like solids but behave like superfluids. The funding comes from the Gordon and Betty Moore (as in, Moore’s Law) Foundation and supports innovative and risky research.

Sinking cornstarch runners

Maybe you are one of the millions who watched YouTube and saw people mix cornstarch—a food thickener—into a shallow pool of water and then run across the surface. This works because cornstarch grains in a dense suspension pack together when someone puts weight on them, the way snowflakes do in front of a plow. Now, a team led by Itai Cohen, a member of the Kavli Institute at Cornell for Nanoscale Science, has found a way to tune those properties so—if you’re a tricky type of experimentalist—you can make your friends sink in the middle of their run. The secret involves rotational oscillation, a more scientific way of saying “squeezing and stretching,” that changes the volume of the suspended particles.