Tiny nets woven from DNA strands can ensnare the spike protein of the virus that causes COVID-19, lighting up the virus for a fast-yet-sensitive diagnostic test—and also impeding the virus from infecting cells, opening a new possible route to antiviral treatment, according to a new study.

Researchers at the University of Illinois Urbana-Champaign and collaborators demonstrated the DNA nets’ ability to detect and impede COVID-19 in human cell cultures in a paper published in the Journal of the American Chemical Society.

“This platform combines the sensitivity of PCR and the speed and low cost of antigen tests,” said study leader Xing Wang, a professor of bioengineering and of chemistry at Illinois. “We need tests like this for a couple of reasons. One is to prepare for the next pandemic. The other reason is to track ongoing viral epidemics—not only coronaviruses, but also other deadly and economically impactful viruses like HIV or influenza.”

DNA is best known for its genetic properties, but it also can be folded into custom nanoscale structures that can perform functions or specifically bind to other structures much like proteins do. The DNA nets the Illinois group developed were designed to bind to the coronavirus spike protein—the structure that sticks out from the surface of the virus and binds to receptors on human cells to infect them. Once bound, the nets give off a fluorescent signal that can be read by an inexpensive handheld device in about 10 minutes.

The researchers demonstrated that their DNA nets effectively targeted the spike protein and were able to detect the virus at very low levels, equivalent to the sensitivity of gold-standard PCR tests that can take a day or more to return results from a clinical lab.

The technique holds several advantages, Wang said. It does not need any special preparation or equipment, and can be performed at room temperature, so all a user would do is mix the sample with the solution and read it. The researchers estimated in their study that the method would cost $1.26 per test.

“Another advantage of this measure is that we can detect the entire virus, which is still infectious, and distinguish it from fragments that may not be infectious anymore,” Wang said. This not only gives patients and physicians better understanding of whether they are infectious, but it could greatly improve community-level modeling and tracking of active outbreaks, such as through wastewater.

In addition, the DNA nets inhibited the virus’s spread in live cell cultures, with the antiviral activity increasing with the size of the DNA net scaffold. This points to DNA structures’ potential as therapeutic agents, Wang said.

“I had this idea at the very beginning of the pandemic to build a platform for testing, but also for inhibition at the same time,” Wang said. “Lots of other groups working on inhibitors are trying to wrap up the entire virus, or the parts of the virus that provide access to antibodies. This is not good, because you want the body to form antibodies. With the hollow DNA net structures, antibodies can still access the virus.”

The DNA net platform can be adapted to other viruses, Wang said, and even multiplexed so that a single test could detect multiple viruses.

“We’re trying to develop a unified technology that can be used as a plug-and-play platform. We want to take advantage of DNA sensors’ high binding affinity, low limit of detection, low cost and rapid preparation,” Wang said.

The paper is titled “Net-shaped DNA nanostructures designed for rapid/sensitive detection and potential inhibition of the SARS-CoV-2 virus.”

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More information: Neha Chauhan et al, Net-Shaped DNA Nanostructures Designed for Rapid/Sensitive Detection and Potential Inhibition of the SARS-CoV-2 Virus, Journal of the American Chemical Society (2022). DOI: 10.1021/jacs.2c04835

Source: DNA nets capture COVID-19 virus in low-cost rapid-testing platform

Nanoengineers at the University of California San Diego have developed microscopic robots, called microrobots, that can swim around in the lungs, deliver medication and be used to clear up life-threatening cases of bacterial pneumonia.

In mice, the microrobots safely eliminated pneumonia-causing bacteria in the lungs and resulted in 100% survival. By contrast, untreated mice all died within three days after infection.

The results are published Sept. 22 in Nature Materials.

The microrobots are made of algae cells whose surfaces are speckled with antibiotic-filled nanoparticles. The algae provide movement, which allows the microrobots to swim around and deliver antibiotics directly to more bacteria in the lungs. The nanoparticles containing the antibiotics are made of tiny biodegradable polymer spheres that are coated with the cell membranes of neutrophils, which are a type of white blood cell. What’s special about these cell membranes is that they absorb and neutralize inflammatory molecules produced by bacteria and the body’s immune system. This gives the microrobots the ability to reduce harmful inflammation, which in turn makes them more effective at fighting lung infection.

[…]

The team used the microrobots to treat mice with an acute and potentially fatal form of pneumonia caused by the bacteria Pseudomonas aeruginosa. This form of pneumonia commonly affects patients who receive mechanical ventilation in the intensive care unit. The researchers administered the microrobots to the lungs of the mice through a tube inserted in the windpipe. The infections fully cleared up after one week. All mice treated with the microrobots survived past 30 days, while untreated mice died within three days.

Treatment with the microrobots was also more effective than an IV injection of antibiotics into the bloodstream. The latter required a dose of antibiotics that was 3000 times higher than that used in the microrobots to achieve the same effect. For comparison, a dose of microrobots provided 500 nanograms of antibiotics per mouse, while an IV injection provided 1.644 milligrams of antibiotics per mouse.

The team’s approach is so effective because it puts the medication right where it needs to go rather than diffusing it through the rest of the body.

[…]

the researchers say that this approach is safe. After treatment, the body’s immune cells efficiently digest the algae, along with any remaining nanoparticles. “Nothing toxic is left behind,” said Wang.

[…]

Source: Tiny swimming robots treat deadly pneumonia i | EurekAlert!

Journal: Nanoparticle-modified microrobots for in vivo antibiotic delivery to treat acute bacterial pneumonia | nature materials