Researchers develop a quantum dot smartphone device to diagnose and track COVID-19

Operational flow of a smartphone diagnostic device to detect COVID-19.

Researchers at the University of Toronto (Institute of Biomedical Engineering, Department of Chemistry, Donnelly Centre for Cellular and Biomolecular Research) in collaboration with Sunnybrook Health Sciences Centre, Public Health Ontario, and Mt. Sinai Hospital have engineered a diagnostic test with a smartphone reader to surveil and track COVID-19 patients. This finding could significantly improve the turnaround time and efficiency for infectious disease diagnosis, for COVID-19 and beyond. The peer-reviewed article can be found in the latest issue of Nano Letters.

“The goal of the study is to make COVID-19 antibody tests more accessible.” said Johnny Zhang, a PhD candidate at the Institute of Biomedical Engineering and Department of Chemistry, and one of the co-first authors of this publication. “The end result is that the patients can take a self-diagnosis for COVID-19 with their phone, and that data can be immediately accessed digitally by medical professionals.”

In a traditional infectious disease diagnostic testing workflow, the clinical sample is obtained from the patient, sent to a laboratory for diagnostic testing, and the result is distributed to clinical personnel for decision making. These processes are often detached in operation and have a long turn-around time.

The researchers engineered quantum dot barcoded microbeads and a secondary label to search for antibodies against COVID-19 antigen in the patient’s blood. Finding the antibodies lead to a change in microbead emission colour. The beads are then loaded into the device, ‘activated’ with a laser, and the signal is imaged using a smartphone camera. An app is designed to process the image to identify the bead’s emission change. Lastly, the data are interpreted and transmitted remotely across the world for data collection and decision making.

Co-authors of this peer-reviewed article. Left: Johnny Zhang, PhD candidate at the Institute of Biomedical Engineering and Department of Chemistry. Right: Ayden Malekjahani, PhD candidate at the Institute of Biomedical Engineering.

“The beauty of the system is that everything is integrated into one, portable unit.” said Zhang.

This technology had been in development for the past 10 years, where the quantum dot microbead detection scheme can measure miniscule amount of infection in the blood.

“We really wanted to improve the performance and utility of the technology this time around,” said Ayden Malekjahani, the other co-first author of this study. “Being able to detect traces of target in patients is not enough. We wanted to add more functions to the device. We designed the device to simultaneously detect multiple antibodies from different sample types, so each test run is packed with information. The results are then uploaded to an online dashboard where medical professionals and the public can see trends in real time.”

The researchers tested this device with forty-nine patient blood sample, where varying degree of COVID-19 infection was present in the patient’s blood. They were able to achieve 84-88% sensitivity, though not as good as tests ran at hospitals. However, this result is still a ~3 times better than current portable antibody test, the lateral flow assay. This result also means detecting COVID-19 antibody can now be done outside of the centralized facilities without sacrificing too much accuracy.

This research was a collaboration with the Public Health Ontario, Sunnybrook Hospital, and Mount Sinai Hospital, where clinical samples were provided to the researchers to test and evaluate this new system.

“This device can be a game-changer in the way we monitor the spread of infectious diseases and a patient’s response to vaccines.” said Dr. Warren Chan, Director and Professor at the Institute of Biomedical Engineering, and the corresponding author of this research.