Reporter | Ge Zhenwei
On April 12, the official website of the Hong Kong Polytechnic University (hereinafter referred to as "PolyU") showed that PolyU has developed a portable covid-19 nucleic acid detector that can conduct on-site testing of collected nucleic acid samples without the need for a laboratory and accurate results within 25 minutes.
The R&D project began in 2020 with the Health and Medical Research Fund allocating more than HK$2.7 million to PolyU's interdisciplinary research team to help them conduct research on portable COVID-19 detectors.
In the past year and a half, the R&D team has successfully carried out accurate COVID-19 detection using reverse transcription thermostatic ring amplification (RT-LAMP) and gold nanoparticles (as nucleic acid amplification displays). Clinical sample test results are in full agreement with reverse transcription polymerase chain reaction (RT-PCR) criteria. Fluorescence quantitative RT-PCR is currently the main nucleic acid detection technology for new coronavirus in mainland China.
From the specific operation point of view, the detector can place six samples at the same time, in addition to two positive and negative control samples, can detect up to four samples at the same time. Once a nucleic acid sample is taken, it can be tested on-site using a detector without having to send the sample back to the lab.
According to reports, the instrument will be set to a constant temperature state of 65 degrees Celsius, and its built-in optical device can detect the precipitation of gold nanoparticles (positive samples will precipitate, while negative samples will remain scattered). The relevant data is instantly transmitted to the phone via Bluetooth and analyzed and displayed in software.
PolyU's portable COVID-19 detector weighs only about 2.4 kilograms and has a volume of 21 cm× 21 cm× 10.5 cm Image source: The official website of the Hong Kong Polytechnic University
Between 10 and 20 minutes, if the optical data displayed on the screen shows an upward trend, it means that the sample is positive, and the faster the data rise, the higher the virus content of the sample, and within 25 minutes, the positive sample can be confirmed, and the entire test is completed within about 40 minutes, and the test results can be identified by the naked eye.
The gold nanoparticles of the positive sample (right) will precipitate, while the negative sample (left) will remain scattered, and the entire test will be completed within about 40 minutes, and the test results will be recognizable by the naked eye. Source: The official website of the Hong Kong Polytechnic University
Professor And Chair of the Department of Medical Technology and Informatics at PolyU, who led the study, said: "The key to the research lies in the gold nanoparticle display agent, which can reach 100% sensitivity and specificity through the detectors we developed, which is in line with the current 'gold standard' of nucleic acid detection of the new crown virus. ”
Another feature of the detector is that it can be operated in an environment outside the laboratory, and it is equipped with a built-in power supply, which can be used after charging, and the entire inspection procedure can be completed on site after sampling.
It is understood that there are two main means of nucleic acid detection at present, one is conventional nucleic acid testing, and the other is rapid antigen testing. The former has a high accuracy rate, but the detection time is relatively long and requires laboratory testing; the latter is fast but the accuracy rate is relatively low.
Team member Dr. Li Minghong, Associate Professor and Deputy Head of the Department of Biomedical Engineering at PolyU, explained that the environmental sample tests conducted by the team have successfully used the constant temperature cyclic amplification method without additional extraction of nucleic acids, which greatly shortens the detection time, does not have to use large nucleic acid testing instruments in the laboratory, and can achieve accurate nucleic acid detection in the small detector.
"Even if the virus volume is low, the accuracy is not affected, and the team will soon begin testing with a human prototype (unexamined nucleic acid)."
Dr. Li Minghong added that the detector can be used to detect human and environmental samples, as well as to detect different viruses and bacteria (with corresponding primers), and the testing cost is lower than RT-PCR.
The research team said that it hopes to transfer the research results, cooperate with the industry, and apply the technology to the community, especially some places that need to get accurate test results in a short period of time, such as airports, shopping malls, clinics, ports, schools, etc.
The research team also revealed that the detector has not yet entered the mass production stage, it is difficult to calculate the actual cost, but it is estimated that the cost of the new technology is cheaper, and it is currently in contact with an international testing agency, hoping to popularize the application in the above scenarios.
As for whether the portable detector will completely replace the currently commonly used nucleic acid testing in the future, according to Hong Kong 01 reports, Professor Ye Sheping believes that although it can theoretically replace the conventional nucleic acid testing method, the relationship between the two should be more "learning from each other's strengths".