Korean researchers said they developed an ultrafast real-time polymerase chain reaction (RT-PCR) technology that detects the Covid-19 virus in just five minutes, shorter than one-tenth of the current RT-PCR test time.
The Korea Advanced Institute of Science and Technology (KAIST) said the research team of professor Jeong Ki-hun at the Department of Bio and Brain Engineering developed an ultrafast PCR technology that enables rapid thermal cycling and real-time quantitative analysis plasmonic nanostructures.
Plasmonic nanostructures are metal nanostructures smaller than the wavelength of light. They are widely applied to biomaterial detection and molecular diagnosis.
The standardized Covid-19 RT-PCR testing involves reverse transcribing RNA, the genetic material of the virus, into complementary DNA, amplifying the target DNA, and detecting the virus with a fluorescent probe. However, the conventional RT-PCR test had a limitation in that the detection time was too long, and the sample had to be moved to a place equipped with expensive and large equipment.
The “real-time nanoplasmonic PCR,” developed by the KAIST team, combines a vacuum-designed microfluidic chip with a nanoplasmonic substrate with a white light-emitting diode (LED). This way, it can rapidly amply and quantitatively analyze a small amount of a sample and detect the virus in a short time.
A nanoplasmonic substrate has gold nanoislands with glass nanopillar arrays, having high light absorption in the entire spectrum of visible light. So, it can quickly generate and emit heat by replacing white LED light with thermal energy. To this, the researchers combined a vacuum-assisted microfluidic chip.
One drop of a sample into the chip will make the fluid vacuumed into the microchamber and automatically injected within three minutes. The microbubbles during the reaction will be removed through the air-permeable wall, raising the efficiency of PCR, the researchers said.
The research team verified the new technology using the Covid-19 virus plasmid DNA. The results showed that the new method performed 40 cycles (95-65 Celsius degrees) in five minutes, with the target virus amplification efficiencies of 91 percent. A typical Covid-19 PCR test takes about an hour.
“We developed an ultrafast molecular diagnostics that can be used on-site,” Jeong said. “Real-time nanoplasmonic PCR will be a next-generation gene amplification platform for on-site molecular diagnosis. It will contribute to curbing the viral spread.”
Ph. D student Kang Byoung-hoon at the KAIST’s Bio and Brain Engineering Department led the study.
On May 19, ACS Nano published the study titled, “Ultrafast and Real-time Nanoplasmonic On-Chip Polymerase Chain Reaction for Rapid and Quantitative Molecular Diagnostics.”