Pamela Cruz. Peninsula 360 Press [P360P].
Researchers at Stanford University developed a highly automated device that can identify the presence of COVID-19 in 30 minutes using lab-on-a-chip technology and the cutting-edge gene-editing technique known as CRISPR.
The microlab, barely half the size of a credit card, is a microfluidic chip that contains a complex network of channels smaller than the width of a human hair, said the study's lead author, Juan G. Santiago.
The Charles Lee Powell Foundation professor of mechanics and microfluidics expert said, "The test can identify an active infection relatively quickly and inexpensively," he said.
Nor does it rely on antibodies like many tests, "which only indicate whether someone has had the disease and not whether they are currently infected and therefore contagious," explained Ashwin Ramachandran, a Stanford graduate student and co-author of the study.
The microlaboratory test takes advantage of the fact that SARS-CoV-2, the virus that causes COVID-19 disease, leaves small genetic fingerprints in the form of RNA strands, the gene product 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 device, which uses electrical fields to extract and purify any nucleic acids, such as RNA. The purified RNA is converted to DNA and then replicated many times using a technique known as isothermal amplification.
Next, an enzyme called CRISPR-Cas12, a sister of the CRISPR-Cas9 enzyme, is used to determine whether some of the amplified DNA came from the coronavirus. If so, the enzyme activates fluorescent probes that make the sample glow.
"Our chip is unique in that it uses electric fields to purify the nucleic acids in the sample and to accelerate the chemical reactions that let us know they are present," Santiago said.
The team of researchers created their device with a budget of about $5,000. For now, the DNA amplification step must be performed outside the chip, but Santiago hopes that in a few months his lab will integrate all the steps on a single chip.
Several human-scale diagnostic tests use similar gene and enzyme amplification techniques, but they are slower and more expensive than the new test, which provides results in just 30 minutes. Other tests may require more manual steps and can 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, tuberculosis and other blood-borne diseases.
