The nanopore optofluidic chip used in the new diagnostic system, with a PCR thermocycler in the background for comparison. Credit: Mohammad Julker Neyen Sampad, UC Santa Cruz
Researchers at UC Santa Cruz have developed a novel rapid-testing method that can replicate the accuracy of PCR tests. The method is amplification-free and label-free, reducing the need for sample preparation dramatically reducing the time required and complexity of the testing.
The method, published in Proceedings of the National Academy of Sciences, combines optofluidics and nanopore technology to create a novel lab-on-a-chip diagnostic system. “This could turn into the next big diagnostic system,” said Aaron Hawkins, professor of Electrical and Computer Engineering at Brigham Young University. “You get sick, you go to the hospital or doctor, and their tests rely on this technology. There’s a path where this could be installed right there [in a hospital or clinic], so you wouldn’t have to wait to get your results.”
Traditionally, PCR tests were considered the gold standard for accuracy when conducting virology testing. However, they are highly complex tests that require extensive sample preparation leading to results not being available for several days. Additionally, PCR tests can only detect nucleic acids. The novel methodology developed by the UC Santa Cruz researchers addresses both of these shortcomings of PCR testing.
Using the new method, a biofluid sample is mixed in a container containing magnetic microbeads with a matching RNA sequence from the disease being tested for. During mixing, if the target virus is present in the sample, it will bind to the microbeads. After mixing, the beads are then added to a silicon microfluidic chip where they flow through a thin channel. During this stage, the beads are pushed into nanopores by a light beam and after heating, any RNA particles present on the beads are sucked into the nanopore which detects the presence of the RNA.
During trials, the test accurately detected the virus in each sample that PCR was able to detect, even at extremely low concentrations. Additionally, the test detected the presence of the virus in certain samples that PCR could not, eluding to the testing being more accurate than PCR.
Currently, the test has been developed and optimized for both SARS-CoV-2 and Zika viruses, but it could be expanded to include any virus that researchers have a genetic sample of. The team intends to further simplify the method while enabling disease multiplexing to allow for the rapid detection of numerous diseases simultaneously.