By IQT News posted 29 Dec 2021

(LaboratoryEquipment) A novel approach to testing for the presence of the virus that causes COVID-19 may lead to tests that are faster, less expensive, and potentially less prone to erroneous results than existing detection methods. Though the work, based on quantum effects, is still theoretical, these detectors could potentially be adapted to detect virtually any virus, the researchers say.
The new approach is described in a paper published in the journal Nano Letters, by Changhao Li, an MIT doctoral student; Paola Cappellaro, a professor of nuclear science and engineering and of physics; and Rouholla Soleyman and Mohammad Kohandel of the University of Waterloo.
Existing tests for the SARS-CoV-2 virus include rapid tests that detect specific viral proteins, and polymerase chain reaction (PCR) tests that take several hours to process. Neither of these tests can quantify the amount of virus present with high accuracy. Even the gold-standard PCR tests might have false-negative rates of more than 25 percent. In contrast, the team’s analysis shows 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.
The new approach makes use of atomic-scale defects in tiny bits of diamond, known as nitrogen vacancy (NV) centers. These tiny defects are extremely sensitive to minute perturbations, thanks to quantum effects taking place in the diamond’s crystal lattice, and are being explored for a wide variety of sensing devices that require 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 bonds to this material, it disrupts the magnetic connection and causes changes in the diamond’s fluorescence that are easily detected with a laser-based optical sensor.
The sensor uses only low-cost materials (the diamonds involved are smaller than specks of dust), and the devices could be scaled up to analyze a whole batch of samples at once, the researchers say. The gadolinium-based coating with its RNA-tuned organic molecules can be produced using common chemical processes and materials, and the lasers used to read out the results are comparable to cheap, widely available commercial green laser pointers.

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