Microrobotic diagnostic system to be evaluated for SARS-CoV-2 detection

Experts at the Chinese University of Hong Kong (CUHK) have developed a fully automated microrobotic diagnostic system for rapid detection of Clostridium difficile at a low cost. The system is now being evaluated for detection of multiple pathogens, including the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

The novel QuickCAS system, developed by a research team led by Professor Li Zhang of the Department of Mechanical and Automation Engineering, uses fluorescent magnetic spore–based microrobots (FMSMs) as a highly specific and sensitive mobile sensing platform to detect toxins secreted by C. difficile present in bacterial culture medium and clinical stool specimens. The FMSMs demonstrated high specificity and sensitivity in screening toxins, with a limit of detection (LOD) comparable to that of enzyme-linked immunosorbent assay (ELISA) (1.73 ng/mL vs 0.8–2.5 ng/mL). [Sci Adv 2019, doi: 10.1126/sciadv.aau9650]

In addition, the technology enables C. difficile detection at a low-cost (HKD 50 per test vs HKD 300 per test for current methods such as cytotoxicity assay, glutamate dehydrogenase assay and polymerase chain reaction [PCR]) and a rapid manner (15–30 minutes vs 2–4 hours to complete), with full automation and less demand in manpower.

“The FMSMs are first coated with a layer of magnetic Fe₃O₄ nanoparticles to produce long-lasting locomotion in various fluids, then functionalized in ethanol and conjugated with carbon fluorescence-emitting carbon dots to selectively target C. difficile toxins,” explained Zhang. “[In contrast to many traditional chemical detection methods,] QuickCAS uses a physical detection method without the need for bioreagents and refrigeration.”

The first generation of QuickCAS has obtained patents in the US and mainland China. “The system will hopefully enable medical centres in remote and poor areas or small-scale healthcare service providers to provide accurate clinical diagnostic services,” he said.

With the coronavirus disease 2019 (COVID-19) pandemic resulting in soaring demands for rapid testing and increased workload for laboratory personnel, the researchers are now studying expanded application of the QuickCAS system for detection of SARS-CoV-2, as well as Streptococcus pneumoniae, Salmonella, pathogenic Escherichia coli and Helicobacter pylori.

“With globalization, the spread of infectious diseases is not restricted to certain geographical areas. To enhance the diagnosis and control of infections, testing using automatic rapid detection systems is the general trend,” said Professor Margaret Ip of the Department of Microbiology, CUHK.