MIT scientists have developed a novel approach for detecting the presence of the SARS-CoV-2 virus. Based on quantum effects, the approach is faster, less expensive, and potentially less prone to erroneous results.
Existing test methods take several hours to process. Neither of these tests can quantify the amount of virus present with high accuracy.
In contrast, the new test could have false-negative rates below 1 percent. The test could also be sensitive enough to detect just a few hundred strands of the viral RNA within just a second.
Scientists created the new approach using atomic-scale defects in tiny bits of diamond, known as nitrogen-vacancy (NV) centers. These tiny defects are susceptible to minute perturbations due to quantum effects in the diamond’s crystal lattice. They are being explored for various sensing devices requiring high sensitivity.
The new method would involve coating the nanodiamonds containing these NV centers with a material that is magnetically coupled to them and has been treated to bond only with the specific RNA sequence of the virus. When the virus RNA is present and binds to this material, it disrupts the magnetic connection. It causes changes in the diamond’s fluorescence that are easily detected with a laser-based optical sensor.
Using only low-cost materials, the sensors could analyze a whole batch of samples at once. The gadolinium-based coating with RNA-tuned organic molecules can be produced using common chemical processes and materials.
Scientists used mathematical simulations and proved that the system could work in principle.
Changhao Li, an MIT doctoral student, Paola Cappellaro, nuclear science and engineering, and physics professor, said, “We don’t know how long it will take to do the final demonstration. Their plan is first to do a basic proof-of-principle lab test, and then to work on ways to optimize the system to make it work on real virus diagnosis applications.”
Paola Cappellaro, a professor of nuclear science and engineering and physics, said, “Even if complications arise in translating the theoretical analysis into a working device, there is such a large margin of lower false negatives predicted from this work that it will likely still have a strong advantage over standard PCR tests in that regard. And even if the accuracy were the same, this method would still have a major advantage in producing its results with a matter of minutes, rather than requiring several hours.”
“The basic method can be adapted to any virus, including any new ones that may arise, simply by adapting the compounds that are attached to the nanodiamond sensors to match the genetic material of the specific target virus.”
David Glenn, a senior research scientist at Quantum Diamond Technologies Inc., who was not associated with this work, said, “The proposed approach is appealing both for its generality and its technological simplicity. In particular, the sensitive, all-optical detection technique described here requires minimal instrumentation compared to other methods that employ nitrogen-vacancy centers.”
- Changhao Li et al. SARS-CoV-2 Quantum Sensor Based on Nitrogen-Vacancy Centers in Diamond. DOI: 10.1021/acs.nanolett.1c02868