Proteins that emit bright blue or green light can make disease diagnosis faster and easier. Photo source: Although Martin Mercks/American Chemical Society has made great progress in highly sensitive diagnostic tests for virus infection, they still need complex techniques to prepare samples or interpret results, which makes their promotion in areas with scarce medical resources impractical. A sensitive method, published in the journal ACS Central Science on the 15th, can analyze viral nucleic acid in just 20 minutes, and can be completed in one step using "luminous" protein. The flash of fireflies, the "bait" of angler fish and the ghostly blue of the beach covered by phytoplankton are all driven by the same scientific phenomenon called bioluminescence. The chemical reaction involving luciferase protein will produce luminous effect. This luciferase protein has been integrated into sensors. When they find the target, these sensors will emit light that is easy to observe. This ease of operation makes these types of sensors ideal for on-site real-time diagnosis and testing, but so far, they still lack high sensitivity, and CRISPR gene editing technology requires many steps and additional special equipment to detect low signals in complex and noisy samples. The research team of Eindhoven University of Technology in the Netherlands uses the proteins related to CRISPR system to combine them with a bioluminescence technology. The signal of this technology can be detected only by a digital camera. In order to ensure that there are enough RNA or DNA samples for analysis, researchers carried out recombinant polymerase amplification (RPA), which is a simple method to work at a constant temperature of about 38 ℃. Using the new technology of luminescent nucleic acid sensor (LUNAS), two CRISPR/Cas9 proteins have specificity for different adjacent parts of the virus genome, and each protein has a unique luciferase fragment attached to them. If the researchers are testing the specific virus genome, these two CRISPR/Cas9 proteins will combine with the target nucleic acid sequence and close to each other, so that the complete luciferase protein will form and emit blue light in the presence of chemical substrate. When testing clinical samples collected from nasal swabs, RPA-LUNAS successfully detected COVID-19 RNA within 20 minutes, even at the concentration of 200 copies per microliter. (Xinhua News Agency)