A new tool promises to expedite detection of infectious disease, according to researchers from McGill University, Montreal.
The diagnostic platform, called The device was tested for several respiratory viruses and bacteria, including the H1N1 influenza virus and SARS-CoV-2. It achieved 95% accuracy at identifying COVID-19 and its variants in 48 human saliva samples.
“COVID was something that opened our eyes, and now we have to think more seriously about point-of-care diagnostics,” Sara Mahshid, PhD, assistant professor of biomedical engineering and Canada Research Chair in Nano-Biosensing Devices at McGill University, said in an interview. The technology could become important for a range of medical applications, especially in low-resource areas.
The development was detailed in an article in Nature Nanotechnology.
Nonclinical setting
The COVID-19 pandemic has demonstrated the need for fast and accurate testing that can be used outside of a clinical setting. The gold-standard diagnostic method is PCR testing, but its accuracy comes with a trade-off. PCR testing involves a lengthy protocol and requires a centralized testing facility.
With QolorEX, the investigators aimed to develop a new test that achieves the accuracy of PCR in an automated tool that can be used outside of a testing facility or hospital setting. Dr. Mahshid noted a particular need for a tool that could be used in congregate settings, such as airports, schools, or restaurants.
The device is compact enough to sit on a tabletop or bench and can be used easily in group settings, according to Dr. Mahshid. In the future, she hopes to further miniaturize the device to make it more scalable for widespread use.
Requiring only a saliva sample, the tool is easy to use. Unlike current COVID-19 rapid tests, which involve several steps, the system is automated and does not require manually mixing reagents. After collecting a sample, a user taps a button in a smartphone or computer application. The device handles the rest.
“We’re not chemists who understand how to mix these solutions,” Dr. Mahshid said. Avoiding those extra steps may reduce the false positives and false negatives caused by user error.
Fast results
QolorEX can return results in 13 minutes, like a rapid antigen test does. Like a PCR test, the device uses nucleic acid amplification. But PCR tests typically take much longer. The sample analysis alone takes 1.5-2 hours.
The new test accelerates the reaction by injecting light-excited “hot” electrons from the surface of a nanoplasmonic sensor. The device then uses imaging and a machine learning algorithm to quantify a color transformation that occurs when a pathogen is present.
The fast, reliable results make the system potentially appropriate for use in places such as airports. Previously, passengers had to wait 24 hours for a negative COVID test before boarding a plane. A device such as QolorEX would allow screening on site.
The ability of the tool to distinguish between bacterial and viral infections so quickly is “an application that is both important and extremely difficult to achieve,” according to Nikhil Bhalla, PhD, in a research briefing. Dr. Bhalla is a lecturer in electronic engineering at Ulster University, Belfast, Ireland.
The researchers hope that by delivering results quickly, the device will help reduce the spread of respiratory diseases and possibly save lives.