Rapid and highly accurate test detects viruses such as Covid-19

The UCF researchers developed a device that detects viruses in the body as fast as - and more accurately than - the current commonly used rapid detection tests.

The optical sensor uses nanotechnology to accurately identify viruses from blood samples in seconds. The researchers say the device can tell with 95 per cent accuracy if someone has a virus, a significant improvement over existing rapid tests, which experts have warned can suffer from low accuracy. Testing for viruses is important for early treatment and to help stop their spread.

The researchers tested the device using samples of Dengue virus, a mosquito transmitted pathogen that causes Dengue fever and is a threat to people in the tropics. However, the technology can also easily be adapted to detect other viruses, such as Covid-19, said study co-author Debashis Chanda, a professor in UCF’s NanoScience Technology Center.

“The sensitive optical sensor, along with the rapid fabrication approach used in this work, promises the translation of this promising technology to any virus detection including Covid-19 and its mutations with high degree of specificity and accuracy,” Chanda said. “Here, we demonstrated a credible technique which combines PCR-like genetic coding and optics on a chip for accurate virus detection directly from blood.”

The nanotech device closely matches the accuracy of the gold-standard PCR-based tests, but with nearly instantaneous results instead of results that can take days to be returned. The accuracy of the UCF device is also a significant improvement over current rapid antigen tests, which the US Food and Drug Administration and US Centers for Disease Control have cautioned could produce inaccurate results if viral loads are low or test instructions are not properly followed.

The device works by using nano-scale patterns of gold that reflect back the signature of a virus if it is present in a sample of blood. Different viruses can be detected by using different DNA sequences that selectively target specific viruses.

Key to the device’s performance is that it can detect viruses directly from blood samples without the need for sample preparation or purification, thus speeding up the test and improving its accuracy.

“A vast majority of biosensors demonstrations in the literature utilise buffer solutions as the test matrix to contain the target analyte,” Chanda said. “However, these approaches are not practical in real-life applications because complex biological fluids, such as blood, containing the target biomarkers are the main source for sensing and at the same time the main source of protein fouling, leading to sensor failure.”

The researchers confirmed the device’s effectiveness with multiple tests that used different virus concentration levels and solution environments, including those with the presence of nontarget virus biomarkers.

Abraham Vazquez-Guardado, the study’s lead author and a postdoctoral fellow at Northwestern University who worked on the research as a doctoral student in Chanda’s lab, said he’s excited about the potential: “Although there have been previous optical biosensing demonstration in human serum, they still require off-line complex and dedicated sample preparation performed by skilled personnel - a commodity not available in typical point of care applications.

“This work demonstrated for the first time an integrated device which separated plasma from the blood and detects the target virus without any pre-processing with potential for near-future practical usages.”

Chanda said that the next steps for the research include adapting the device to detect more viruses.

The research was partially supported by National Science Foundation and UCF’s Covid-19 Artificial Intelligence and Big Data Initiative program. The resulting research paper - DNA-Modified Plasmonic Sensor for the Direct Detection of Virus Biomarkers from the Blood - has been published in the journal Nano Letters.