Study shows clinical laboratories may one day use nanorobotic tests to help prevent spread of viral infections, cancer, and other diseases
Scientists from the University of Illinois Urbana-Champaign (U of I) have developed a tiny robotic “hand” made from structural DNA that “grabs” viruses—including the COVID-19 coronavirus—potentially preventing them from infecting cells. Such a nano-robotic antiviral technology could be used by anatomic pathologists and clinical laboratory managers in the future as a point-of-care type of test.
This is yet another example of out-of-the-box thinking by developers of diagnostic technology. Led by Xing Wang, PhD, professor of bioengineering and of chemistry at the U of I, the scientists dubbed their DNA device the NanoGripper.
Similar to a piece of origami (Japanese art of folded paper), the so-called hand has “four bendable fingers and a palm, all in one nanostructure folded from a single piece of DNA,” according to a U of I news release. The scientists found in their study that the hand was capable of doing a rapid test to identify the (COVID-19) virus and “prevented the viral spike proteins from infecting the cells,” Gizmodo reported.
“We are using DNA for its structural properties. It is strong, flexible, and programmable. Yet even in the DNA origami field, this is novel in terms of the design principle. We fold one long strand of DNA back and forth to make all of the elements, both the static and moving pieces, in one step,” said Wang in the news release.
“It would be very difficult to apply it after a person is infected, but there’s a way we could use it as a preventive therapeutic,” said Xing Wang, PhD (above), associate professor, bioengineering and chemistry, University of Illinois Urbana-Champaign, in a news release. “We could make an anti-viral nasal spray compound. The nose is the hot spot for respiratory viruses, like COVID or influenza. A nasal spray with the NanoGripper could prevent inhaled viruses from interacting with the cells in the nose.” Clinical laboratories may one day perform antiviral testing that uses U of I’s NanoGripper technology. (Photo copyright: University of Illinois.)
How a DNA Nanorobot Grabs a Virus
The U of I researchers wanted to leverage what has been discovered about DNA as a “material for constructing versatile nanorobots for biomedical applications,” they wrote in Science Robotics. However, previous studies had not achieved the current origami design of a nanoscale mechanism, the authors added.
With robotic precision and its DNA structure, the researchers’ NanoGripper moves and enables fingers to bend for “customized interactions with target molecules,” Interesting Engineering reported, adding that the technology also:
Employed DNA aptamers on the fingers which act as “molecular locks” to find and bind to specific targets.
In a demonstration, wrapped its fingers around the target spike protein of the COVID-19 coronavirus, essentially “disabling its ability to infect cells.”
“The aptamers are arranged into a spatial pattern that specifically matches that of the trimeric spike protein on the virus outer surface. Such pattern recognition-enabled multivalent interaction—a principle developed by my group—has induced ultrahigh NanoGripper virus-binding avidity, resulting in enhanced virus diagnosis sensitivity,” Wang said.
Taken from the U of I news release, the image above shows how “Inspired by the gripping power of the human hand and bird claws, the researchers designed the NanoGripper with four bendable fingers and a palm, all in one nanostructure folded from a single piece of DNA. Each finger has three joints, like a human finger, and the angle and degree of bending are determined by the design on the DNA scaffold.” Such nano-robotic technology could become a new clinical laboratory test for diagnosing viral infections, or even a preventative treatment if caught prior to infection. (Photo and caption copyright: University of Illinois.)
Developing a Test for COVID-19
The scientists discovered that when equipped with a photonic crystal sensor, NanoGripper detected the SARS-CoV-2 coronavirus in 30 minutes with sensitivity equal to RTqPCR tests, Gizmodo reported.
“The NanoGripper functions as a highly sensitive biosensor that selectively detects intact SARS-CoV-2 virions in human saliva with a limit of detection of 100 copies per milliliter, providing a sensitivity equal to that of reverse transcription quantitative polymerase chain reaction [RTqPCR],” the authors wrote in Science Robotics.
In fact, the NanoGripper test is reportedly faster and easier than RTqPCR testing, which requires sophisticated instruments.
“Our test is very fast and simple since we detect the intact virus directly,” said study collaborator Brian Cunningham, PhD, professor, electrical and computer engineering and bioengineering at U of I, in the news release.
“When the virus is held in the NanoGripper’s hand, a fluorescent molecule is triggered to release light when illuminated by an LED or laser,” he said, adding, “When a large number of fluorescent molecules are concentrated upon a single virus, it becomes bright enough in our detection system to count each virus individually.”
More Research and Applications
Gizmodo compared the NanoGripper to a “true Swiss army knife,” able to change and detect other viruses such as HIV and influenza (Flu).
The U of I researchers have already studied the NanoGripper’s ability to detect hepatitis B and plan to publish findings soon, Wang told The Pathologist. He also noted it’s possible the NanoGripper “can be integrated with a lateral flow assay paper strip platform for development of a rapid, sensitive, and inexpensive at home or point-of-care virus detection.”
There is “power in soft nanorobotics,” said Wang, who envisions potential for the NanoGripper beyond viruses to include programming the fingers to detect cancer markers and enabling the grippers to deliver treatment to target cells.
Clinical pathologists and laboratory managers may want to follow this research coming out of the University of Illinois Urbana-Champaign. Once put through additional clinical studies, such nanorobotic diagnostic technology might eventually be used at the point-of-care to help prevent viral infection and spread of disease.
This “Virus Trap” might eventually be manufactured by clinical laboratories for the diagnostic process
Clinical laboratory managers and pathologists will be fascinated by this new treatment coming out of Germany for viral infections. It’s an entirely different technology approach to locating and neutralizing live viruses that may eventually be able to control anti-viral-resistant strains of specific viruses as well.
As virologists and microbiologists are aware, even in our present era of technological and medical advances, viral infections are extremely difficult to treat. There are currently no effective antidotes against most viral infections and antibiotics are only successful in fighting bacterial infections.
Thus, this new technology developed by a research team at the Technical University of Munich (TUM) in Munich, Germany, that uses DNA origami to neutralize and trap viruses and render them harmless is sure to gain swift attention, especially given the world’s battle with the SARS-CoV-2 Omicron variant.
“Bacteria have a metabolism. We can attack them in different ways,” said virologist Ulrike Protzer, MD (above), Director of the Institute of Virology at TUM School of Medicine and one of the authors of the study, in a TUM press release. “Viruses, on the other hand, do not have their own metabolism, which is why antiviral drugs are almost always targeted against a specific enzyme in a single virus. Such a development takes time. If the idea of simply mechanically eliminating viruses can be realized, this would be widely applicable and thus an important breakthrough, especially for newly emerging viruses,” she added. (Photo copyright: Helmholtz Munich.)
Entrapping Viruses within 3D Hollow Structures
DNA origami is the nanoscale folding of DNA to create two- and three-dimensional complex shapes that can be manufactured with a high degree of precision at the nanoscale. Researchers have been working with and enhancing this technique for about 15 years.
However, scientists at TUM wondered if they could create such hollow structures based on the capsules that encompass viruses to entrap those viruses. They developed a method that made it possible to create artificial hollow bodies the size of a virus and explored using those hollow bodies as a type of “virus trap.”
The researchers theorized that if those hollow bodies could be lined on the inside with virus-binding molecules, they could tightly bind the viruses and remove them from circulation. For this method to be successful, however, those hollow bodies had to have large enough openings to ensure the viruses could get into the shells.
“None of the objects that we had built using DNA origami technology at that time would have been able to engulf a whole virus—they were simply too small,” said Hendrik Dietz, PhD, Professor of Physics at TUM and an author of the study in a press release. “Building stable hollow bodies of this size was a huge challenge,” he added.
So, the team of researchers used the icosahedron geometric shape, which is an object comprised of 20 sides. They engineered the hollow bodies for their virus trap from three-dimensional, triangular plates which had to have slightly beveled edges to ensure the binding points would assemble properly to the desired objects.
“In this way, we can now program the shape and size of the desired objects using the exact shape of the triangular plates,” Dietz explained. “We can now produce objects with up to 180 subunits and achieve yields of up to 95%. The route there was, however, quite rocky, with many iterations.”
By varying the binding points on the edges of the triangles, the scientists were able to create closed hollow spheres and spheres with openings or half-shells that could be utilized as virus traps. They successfully tested their virus traps on adeno-associated viruses (AAV) and hepatitis B viruses in cell cultures.
“Even a simple half-shell of the right size shows a measurable reduction in virus activity,” Dietz stated in the press release. “If we put five binding sites for the virus on the inside—for example suitable antibodies—we can already block the virus by 80%. If we incorporate more, we achieve complete blocking.”
The team irradiated their finished building blocks with ultraviolet (UV) light and then treated the outside with polyethylene glycol and oligolysine. This process prevented the DNA particles from being immediately degraded in body fluids. Those particles were stable in mouse serum for 24 hours. The TUM scientists plan to test their building blocks on living mice soon.
“We are very confident that this material will also be well tolerated by the human body,” Dietz said.
Could Clinical Laboratories Manufacture Components of the Virus Traps?
The researchers noted that the starting materials for their virus traps can be mass produced at a very reasonable cost and may have other uses.
“In addition to the proposed application as a virus trap, our programmable system also creates other opportunities,” Dietz said. “It would also be conceivable to use it as a multivalentantigen carrier for vaccinations, as a DNA or RNA carrier for gene therapy, or as a transport vehicle for drugs.”
There is much research yet to be done on this cutting-edge technology. However, for this therapy to be appropriate for a patient, a specimen of the virus will need to be identified and studied. Then, the DNA origami would be tailored to capture that specific virus. Thus, it’s conceivable that clinical laboratories, if used for the diagnostic step, might also be able to then manufacture the virus trap that is customized to locate, surround, and neutralize that specific virus.
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