Illinois researchers found that crumpling graphene in DNA sensors made it tens of thousands of times more sensitive, making it a feasible platform for liquid biopsy.
Image courtesy of Mohammad Heiranian
CHAMPAIGN, IL — Graphene-based biosensors could usher in an era of liquid biopsy, detecting DNA cancer markers circulating in a patient’s blood or serum. But current designs need a lot of DNA. In a new study, crumpling graphene makes it more than ten thousand times more sensitive to DNA by creating electrical “hot spots,” researchers at the University of Illinois at Urbana-Champaign found.
Crumpled graphene could be used in a wide array of biosensing applications for rapid diagnosis, the researchers said. They published their results in the journal Nature Communications.
“This sensor can detect ultra-low concentrations of molecules that are markers of disease, which is important for early diagnosis,” said study leader Rashid Bashir, a professor of bioengineering and the dean of the Grainger College of Engineering at Illinois. “It’s very sensitive, it’s low-cost, it’s easy to use, and it’s using graphene in a new way.”
While the idea of looking for telltale cancer sequences in nucleic acids, such as DNA or its cousin RNA, isn’t new, this is the first electronic sensor to detect very small amounts, such as might be found in a patient’s serum, without additional processing.
“When you have cancer, certain sequences are overexpressed. But rather than sequencing someone’s DNA, which takes a lot of time and money, we can detect those specific segments that are cancer biomarkers in DNA and RNA that are secreted from the tumors into the blood,” said Michael Hwang, the first author of the study and a postdoctoral researcher in the Holonyak Micro and Nanotechnology Lab at Illinois.
Graphene—a flat sheet of carbon one atom thick—is a popular, low-cost material for electronic sensors. However, nucleic-acid sensors developed so far require a process called amplification—isolating a DNA or RNA fragment and copying it many times in a test tube. This process is lengthy and can introduce errors. So Bashir’s group set out to increase graphene’s sensing power to the point of being able to test a sample without first amplifying the DNA.
Many other approaches to boosting graphene’s electronic properties have involved carefully crafted nanoscale structures. Rather than fabricate special structures, the Illinois group simply stretched out a thin sheet of plastic, laid the graphene on top of it, then released the tension in the plastic, causing the graphene to scrunch up and form a crumpled surface.
They tested the crumpled graphene’s ability to sense DNA and a cancer-related microRNA in both a buffer solution and in undiluted human serum, and saw the performance improve tens of thousands of times over flat graphene.
“This is the highest sensitivity ever reported for electrical detection of a biomolecule. Before, we would need tens of thousands of molecules in a sample to detect it. With this device, we could detect a signal with only a few molecules,” Hwang said. “I expected to see some improvement in sensitivity, but not like this.”
To determine the reason for this boost in sensing power, mechanical science and engineering professor Narayana Aluru and his research group used detailed computer simulations to study the crumpled graphene’s electrical properties and how DNA physically interacted with the sensor’s surface.
They found that the cavities served as electrical hotspots, acting as a trap to attract and hold the DNA and RNA molecules.
“When you crumple graphene and create these concave regions, the DNA molecule fits into the curves and cavities on the surface, so more of the molecule interacts with the graphene and we can detect it,” said graduate student Mohammad Heiranian, a co-first author of the study. “But when you have a flat surface, other ions in the solution like the surface more than the DNA, so the DNA does not interact much with the graphene and we cannot detect it.”
In addition, crumpling the graphene created a strain in the material that changed its electrical properties, inducing a bandgap—an energy barrier that electrons must overcome to flow through the material—that made it more sensitive to the electrical charges on the DNA and RNA molecules.
“This bandgap potential shows that crumpled graphene could be used for other applications as well, such as nano circuits, diodes, or flexible electronics,” said Amir Taqieddin, a graduate student and coauthor of the paper.
Even though DNA was used in the first demonstration of crumpled graphene’s sensitivity for biological molecules, the new sensor could be tuned to detect a wide variety of target biomarkers. Bashir’s group is testing crumpled graphene in sensors for proteins and small molecules as well.
“Eventually the goal would be to build cartridges for a handheld device that would detect target molecules in a few drops of blood, for example, in the way that blood sugar is monitored,” Bashir said. “The vision is to have measurements quickly and in a portable format.”
– This press release was originally published on the Illinois News Bureau website
Celebrate Yuri's Night 2020 online with Bill Nye, astronauts and more this weekend! – Space.com
This Saturday (April 11), 50 years after Apollo 13 launched to the moon, you can celebrate human spaceflight with a Yuri’s Night livestream event.
Yuri’s Night events have been held annually since 2001 and were originally designed as a way to celebrate human spaceflight. The event is named after cosmonaut Yuri Gagarin, who became the first human to go to space on April 12, 1961.
In addition to the main annual Yuri’s Night event, including music, art, science and more, people also independently throw their own “Yuri’s Nights” all around the world however they want in whatever location they want.
However, while “there is no ‘typical’ Yuri’s Night party,” Tim Bailey, executive director of Yuri’s Night, told Space.com in an email, this weekend will certainly be different from previous celebrations. “This year almost all local events have been canceled to help slow the spread of the coronavirus,” he said. The closures also mean that the annual event will be livestreamed.
But the online event will feature an all-star cast of scientists, artists and astronauts who will be participating in the event. Spaceflyers taking part include South Korean astronaut Soyeon Yi, Canadian astronaut Chris Hadfield and retired NASA astronauts Nicole Stott and Scott Kelly, Bailey said, while other guests include celebrity science communicator Bill Nye, former rocket scientist and current CEO of Girl Scouts of the USA Silvia Acevedo, founding member of the Grateful Dead Bob Weir and “Star Trek: Voyager” actor Robert Picardo.
Alongside the livestream, Yuri’s Night will hold a costume contest to mark the occasion, so don your favorite flight suit or get creative and make an imaginative space-inspired costume with things you already have at home. You could even win “fabulous prizes,” Bailey said, if you enter your costume by posting it on Twitter with the hashtag #YurisNight.
You can watch the livestream and stay up-to-date with the evolving list of guests here.
Mercury-bound spacecraft buzzes Earth, beams back pictures – CityNews Edmonton
CAPE CANAVERAL, Fla. — A Mercury-bound spacecraft swooped past Earth on Friday, tweaking its round-about path to the solar system’s smallest and innermost planet.
Launched 1 1/2 years ago, Europe and Japan’s Bepi-Colombo spacecraft passed within 8,000 miles (12,700 kilometres) of Earth. The closest approach occurred over the South Atlantic, with telescopes in Chile catching a glimpse of the speeding spacecraft.
The gravity tug from Earth slowed Bepi-Colombo and put it on a course closer to the sun.
It was the first of nine planetary gravity assists — and the only one involving Earth — on the spacecraft’s seven-year journey to Mercury. The spacecraft — comprised of two scientific orbiters — should reach Mercury in 2025, after swinging twice past Venus and six times past Mercury itself. The next flyby will be at Venus in October.
Before leaving Earth’s vicinity, Bepi-Colombo beamed back black-and-white pictures of the home planet. The spacecraft holds three GoPro-type cameras.
“These selfies from space are humbling, showing our planet, the common home that we share, in one of the most troubling and uncertain periods many of us have gone through,” Gunther Hasinger, the European Space Agency’s science director, said via Twitter.
The space agency’s control centre in Germany had fewer staff than usual for Friday’s operation because of the coronavirus pandemic. The ground controllers sat far apart as they monitored the flyby. Data from the flyby will be used to calibrate Bepi-Colombo’s science instruments.
Scientists hope to learn more about the origin and composition of Mercury, once the European and Japanese orbiters separate and begin their own circling of the scorched planet.
Mercury is the least explored of our solar system’s four rocky planets. It’s just a little bigger than our moon and circles the sun in just 88 days.
The spacecraft is named after Italian mathematician and engineer Giuseppe “Bepi” Colombo, who devised the use of planetary flybys for Mercury encounters. He died in 1984.
The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Department of Science Education. The AP is solely responsible for all content.
Marcia Dunn, The Associated Press
50 years after Apollo 13, we can now see the moon as the astronauts did – Space.com
This Saturday (April 11) will mark 50 years since NASA’s Apollo 13 mission launched on an unexpectedly tumultuous journey around the moon. Now, a modern lunar orbiter has reconstructed what the Apollo 13 astronauts would have seen of the lunar surface.
Famously described as a “successful failure,” Apollo 13 did not go as planned: An oxygen tank exploded 56 hours into the mission. Thankfully, some fast-thinking teamwork between the astronauts and mission control back on Earth salvaged the mission and, after a trip around the moon, the astronauts safely returned to Earth.
So, while the crew didn’t land on the moon as planned, they did travel around it and, thanks to modern technology, we can now see what they saw on this journey.
A photo of the lunar surface taken by the Apollo 13 astronauts on their trip around the moon.
Soon after sunrise, the Apollo 13 crew snapped this incredible shot of the moon.
A snapshot of the Tsiolkovskiy crater, taken by the Apollo 13 crew with a telephoto lens.
Researchers used data from NASA’s Lunar Reconnaissance Orbiter mission to recreate what the Apollo 13 crew saw as they flew around the far side of the moon. In the video, you can see craters and other lunar features emerge from the darkness. You can imagine yourself as any of the crewmembers — commander Jim Lovell, command module pilot Jack Swigert or lunar module pilot Fred Haise — looking down and watching the lunar surface pass by as the spacecraft flew overhead.
In addition to the Lunar Reconnaissance Orbiter data, the researchers also consulted the Apollo 13 flight plan and, despite the major change in plans with the mission, were able to use the position and speed at the craft’s closest point to the Moon which was listed in the Apollo 13 Mission Report. Taken together, those details allowed them to determine factors including the position and speed of the spacecraft at its closest point to the moon, which helped clarify the vehicle’s trajectory.
To create this virtual trip around the moon, this team was also informed by photos taken by the Apollo 13 crew during this trip around the moon. You can see some of the captivating original images above, but you can also find every Apollo 13 photo ever online in the Apollo Image Atlas.
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