Chinese researchers have developed a biological sensor they say can detect the new coronavirus in 10 minutes from a throat swab, based on initial study results.
The sensing chip developed by a Peking University team fits a portable, laptop-sized device, and the scientists said it detected the Sars-CoV-2 viral gene almost instantly during their testing.
A year after the coronavirus was first identified, it can take hours or days to get a result from the standard PCR – or polymerase chain reaction – test after a swab is taken because of the time-consuming process required to analyse samples in a laboratory. PCR tests amplify the genes of the virus with chemical agents so they can be seen under fluorescent light.
According to the team, their device was as accurate as PCR testing in the study – and much faster.
Their peer-reviewed paper on the technology, published in the journal Science China Materials last week, said the chip could be used in almost any point-of-care facility and could save time and money, especially for travellers who need to show a negative test result before they can board a plane.
Team leader Guo Xuefeng, a professor of chemical engineering at the university, said in the paper the technology was “ready for immediate application”.
On-the-spot virus detection has been high on public health wish lists for decades. Scientists have proposed numerous solutions to the technical hurdles, but “they never made it out of the lab because there was no demand”, said a Beijing-based government epidemiologist who was not involved in the study and declined to be named.
According to the paper, the technology developed by Guo’s team requires just a tiny fluid sample that is heated on the surface of the chip to 85°C for nine minutes. The heat kills the virus, if it is present, and breaks up the viral envelope to expose viral genes.
The chip is then cleaned with deionised water, leaving the Sars-CoV-2 genes. They remain on the chip’s surface because of its coating – an extremely thin mesh of carbon known as graphene – which has been designed to bind specifically with the new coronavirus.
To detect the virus, electricity is then applied to the chip. Viral genes on the graphene increase conductivity on the chip surface, so measuring small changes in the electrical current indicates whether a sample is positive or negative.
The scientists tested the device with throat swabs taken from six Covid-19 patients and three healthy individuals. They said their results were the same as the PCR tests also conducted, with more than 99% accuracy.
Guo and his team have patented the chip, but its future use remains unclear. Researchers who were not involved in the study said mass production of a graphene-based chip could be difficult because of potential quality issues that could affect its reliability. Guo could not immediately be reached for comment.
The technology, known as a biological field effect transistor, has been around for decades. But there are challenges to creating chip-based virus tests – there are none on the market at present – including fabricating the extremely fine structure on the chip’s surface and interpreting weak electrical signals.
Zhu Yingchun, a researcher with the Shanghai Institute of Ceramics under the Chinese Academy of Sciences who studies biological sensors but was not involved in the study, said using the technology to detect viruses quickly was “now possible” since most of the technical problems had been solved.
But he said many of the laboratories that developed such devices were not equipped to deal with a pathogen like Sars-CoV-2.
“The coronavirus is a highly infectious pathogen that must be handled in biosafety labs,” Zhu said. “Most electrical engineers do not have access to these facilities.” – South China Morning Post