In 2020, an interdisciplinary research team from Hong Kong Polytechnic University (PolyU) received more than HK$2.7 million from the Medical and Health Research Fund (HMRF) to begin research on a test device wearable for COVID-19 (the device).
After a year and a half of extensive work, the team achieved highly sensitive detection of SARS-CoV-2 viral RNA based on the combination of reverse transcription loop-mediated isothermal amplification (RT-LAMP ) and gold nanoparticles (as a reactive amplification result). Clinical sample test results were in full agreement with the reverse transcription polymerase chain reaction (RT-PCR) standard.
The device can accommodate up to six test samples at a time. Excluding a positive control sample and a negative control sample, up to four samples can be tested at the same time. Once the samples have been collected, testing can be performed on-site using the device, without the need to return the samples to the lab.
The device provides a constant temperature of 65°C, and the built-in optical system will monitor the precipitation or dispersion of gold nanoparticles (precipitated in positive samples, while remaining dispersed in negative samples). Real-time data will be sent to a mobile app via Bluetooth, and the test results will be analyzed and displayed on the phone screen.
An increase in the optical signal between 10 and 20 minutes indicates a positive sample, and the shorter the time of appearance, the higher the viral load in the sample. A positive sample can be confirmed in as little as 25 minutes. The whole test can be done in about 40 minutes, and the test results can be recognized by the naked eye.
PolyU’s Vice President (Research and Innovation) remarked that the team is grateful to the Food and Health Office for their confidence in PolyU. With strong support from HMRF, PolyU has been able to leverage its interdisciplinary strengths to contribute to the government’s anti-pandemic measures and translate research findings into real-world applications, bringing benefits to the community.
The leader of the research project, Professor YIP Shea-ping, Professor and Head of the Department of Health and Informatics Technologies of PolyU, pointed out that the use of gold nanoparticles as a reagent for reading the results of Amplification was key to the success of this research. The team is pleased to see that their method has achieved excellent sensitivity and specificity, which is comparable to the current “gold standard” of PCR.
The device’s portable and rechargeable design allows all testing procedures to be performed outside of the laboratory, right after on-site sample collection. Dr. LEE Ming-hung Thomas, Associate Professor and Associate Head of PolyU’s Department of Biomedical Engineering, is a key member of the research team.
Preliminary testing of environmental samples was performed using gold in the nanoparticle-based RT-LAMP method, even without prior nucleic acid extraction and purification. As a result, the test run time was shortened and no large lab equipment was required. Nucleic acid testing can be performed in a convenient device, and accuracy is unaffected even with low viral load. The next important step is to test directly with unpurified human samples, he added.
Both human and environmental samples can be tested in the newly invented device. Besides SARS-CoV-2, other viruses and bacteria can also be detected using this device (primers need to be redesigned). The unit cost of the tests is comparatively lower than that of RT-PCR.
Going forward, the team plans to transfer the research results to society by working with industry players to expand the use of this technology to the wider community, especially in places where accurate results are needed in a short period of time (eg airports, quarantine residences for the elderly, clinics, ports, restaurants, shopping malls, schools, sports and recreational facilities, etc.).
The team also hopes that with this invention in place, personal and environmental hygiene management can be improved and that appropriate control measures can be implemented to reduce the risk of community infection.