For Quick COVID-19 Testing
Techniques and prototypes for quick COVID-19 testing are coming out one after another so that the testing can be carried out anytime and anywhere.
At present, RT-PCR is generally used for the purpose. Although this technique is highly accurate, it takes at least six hours as a specimen needs to be sent to a medical facility and nucleic acid amplification needs to be conducted.
Various organizations are working on point-of-care testing to overcome this limitation. For instance, the Korea Advanced Institute of Science and Technology (KAIST) announced on Sep. 16 that its research team led by professor Jung Hyun-jung developed an isothermal coffee ring (iCoRi) assay for rapid bacterial and viral testing.
The team conducted experiments on methicillin-resistant Staphylococcus aureus (MRSA) and mecA, an antibiotic-resistance gene. The testing was completed in 30 minutes in the experiments and the team is continuing with its research to apply the assay to COVID-19 testing.
The assay is based on the coffee ring effect, in which a ring-shaped pattern on the surface of an object varies with factors such as a capillary and the surface tension of the substance. The team used a special liquid that leaves a stain similar to the coffee ring and found out that the stain becomes faint when the liquid is mixed with, for example, a virus. This is because of the chemical reaction between the molecules of the liquid and the nucleic acid of the virus and the stain becomes fainter and fainter as the concentration of the virus increases.
According to the research team, it is possible to find out the presence or absence and the quantity of the virus in the specimen in just 30 minutes by observing how the stain changes. In addition, mobile devices such as smartphones can be used for data recording and confirmation and the testing cost can be reduced without the need of expensive equipment.
The research team also applied an amplification technique for higher sensitivity and made it possible to detect the virus in the in zeptomole concentration range. One zeptomole is a low level of concentration in which six substance molecules are dissolved in 10 milliliters of liquid. Existing COVID-19 testing kits’ detection capabilities stand at a level at least 1,000 times higher.
The Korea Research Institute of Chemical Technology (KRICT), in the meantime, is leading the government-level development of rapid testing kits. In July this year, the institute came up with antigen testing that takes less than 15 minutes. Here, a nanometer-scale antibody causing a chemical reaction by binding to a COVID-19 antigen is used as a sample and the reaction can be observed with the unaided eye. This technique is predicted to be similar in form to a pregnancy test kit when used as a COVID-19 test kit. It has been transferred to Precision Bio and the company is planning to put it to commercial use within this year.
Local LED manufacturer GeumVit signed a memorandum of understanding in June with the Ben-Gurion University of Israel to supply its terahertz spectroscopy-based test kit to Asian countries. The kit uses the properties of terahertz-frequency light that significantly change when the light passes through a substance containing 100 nm to 140 nm particles. According to the company, the coronavirus has a similar size and thus can be detected based on the same properties. This method provides a result within one minute and each test based on it costs just US$50 or so. The accuracy of diagnosis was over 90 percent in the recent 150-subject clinical trial conducted with the Ministry of Defense of Israel.