Stanford engineers are developing a genetic microlab that can detect COVID-19 in minutes.

Using “lab on a chip” technology, Stanford engineers have created a micro-laboratory that is half the size of a credit card and can detect COVID-19 in just 30 minutes.

During the pandemic, infectious disease experts and frontline health workers demanded a faster, cheaper, and more reliable COVID-19 test. Using technology known as “Lab on a Chip” and cutting-edge CRISPR gene processing technology, Stanford researchers have now developed a highly automated device with which the presence of the novel coronavirus can be identified in just half an hour.

“The Microlab is a microfluidic chip that is half the size of a credit card and contains a complex network of channels that are smaller than the width of a human hair,” said study lead author Juan G. Santiago. , Professor of Mechanics at Stanford’s Charles Lee Powell Foundation Engineering and an expert in microfluidics, a field dedicated to controlling liquids and molecules at the microscale using chips.

The new COVID-19 test is described in a study published November 4 in the Proceedings of the National Academy of Sciences. “Our test can identify an active infection relatively quickly and inexpensively. Nor is it based on antibodies like many tests, which only show whether someone has had the disease and not whether they are currently infected and therefore contagious, ”said Ashwin Ramachandran, a Stanford doctoral student and first author of the study.

The Microlab test takes advantage of the fact that coronaviruses such as SARS-COV-2, the virus that causes COVID-19, leave tiny genetic fingerprints in the form of strands of RNA, the genetic precursor of DNA. If coronavirus RNA is present in a swab sample, the person from whom the sample was taken is infected.

To initiate a test, liquid from a nasal swab sample is dropped into the microlab, which uses electric fields to extract and purify any nucleic acids such as RNA that may be present. The purified RNA is then converted to DNA and then replicated many times using a technique known as isothermal amplification.

Next, the team used an enzyme called CRISPR-Cas12 – a sibling of the CRISPR-Cas9 enzyme associated with this year’s Nobel Prize in Chemistry – to determine if the amplified DNA came from the coronavirus.

In this case, the activated enzyme triggers the fluorescent probes that make the sample glow. Again, electric fields play a vital role in helping to keep all the key ingredients – the target DNA, the CRISPR enzyme, and the fluorescent probes – in a tiny space that is smaller than the width of a human hair, which the probability to interact greatly increases.

“Our chip is unique in that it uses electric fields to purify nucleic acids from the sample and accelerate the chemical reactions that let us know they are present,” Santiago said.

The team developed their device on a tight budget of around $ 5,000. For now, the DNA amplification step has to be done off-chip, but Santiago expects his lab to integrate all the steps into a single chip within months.

Several human-scale diagnostic tests use similar gene and enzymatic amplification techniques, but are slower and more expensive than the new test, which provides results in just 30 minutes. Other tests may require multiple manual steps and take several hours.

The researchers say their approach is not specific to COVID-19 and could be adapted to detect the presence of other harmful microbes such as E. coli in food or water samples or tuberculosis and other diseases in the blood.

“If we want to look for another disease, we simply design the appropriate nucleic acid sequence on a computer and email it to a commercial synthetic RNA manufacturer. They are sending back a vial with the molecule that completely reconfigures our test for a new disease, ”Ramachandran said.

Researchers are working with Ford Motor Company to further integrate the stages and develop their prototype into a marketable product.

Reference: “Electric Field Guided Microfluidics for CRISPR-Based Rapid Diagnostics and Their Application for SARS-CoV-2 Detection” by Ashwin Ramachandran, Diego A. Huyke, Eesha Sharma, Malaya K. Sahoo, ChunHong Huang, Niaz Banaei, Benjamin A. Pinsky and Juan G. Santiago, November 4, 2020, procedure of the National Academy of Sciences.
DOI: 10.1073 / pnas.2010254117.