Using “lab on chip” technology, Stanford engineers created a microlab the size of a detectable credit card half. COVID-19 in just 30 minutes.
During the pandemic, infectious disease specialists and frontline health workers ordered a faster, cheaper, and more reliable COVID-19 test. Now, leveraging the so-called “chip lab” technology and advanced gene editing technique called CRISPR, researchers at Stanford have created a highly automated device that can determine presence of coronavirus as early as half an hour. .
The study’s senior author, Juan G. Santiago, Professor of Mechanical Engineering at the Charles Lee Powell Foundation, said: “A microlab is a super-liquid chip half the size of a credit card that contains a complex network of channels. The trash is smaller than the width of a human hair. engineers at Stanford and an expert in microfluidics, a field devoted to controlling liquids and molecules on a small scale using chips.
The new COVID-19 test is detailed in a study published Nov. 4 in the journal. Proceedings of the National Academy of Sciences. “Our testing can identify an active infection relatively quickly and cheaply. Ashwin Ramachandran, a Stanford graduate and the first author of the study, explained that it also doesn’t rely on antibodies like many tests, but only to tell if someone has the disease, not whether are they infected and therefore contagious.
Microlab testing takes advantage of the fact that coronaviruses like SARS-COV-2, the virus that causes COVID-19, leave microscopic genetic fingerprints wherever they pass as fibers. RNA, the genetic precursor of DNA. If the coronavirus RNA is present in the cotton swab sample, the person sampled is infected.
To begin the test, the liquid from the cotton swab sample is dropped into the microlab, which uses the electric field to extract and purify any nucleic acids such as the RNA it may contain. The pure RNA is then converted into DNA and then replicated multiple times using a technique known as isothermal amplification.
Next, the team used an enzyme called CRISPR-Cas12 – a brother of the CRISPR-Cas9 enzyme involved in this year’s Nobel Prize in Chemistry – to determine if any amplified DNA came from. coronavirus or not.
If so, the enzyme activated will activate the fluorescent probes to make the sample glow. Here, the electric field plays an important role by helping to gather all the important components – the target DNA, the CRISPR enzyme and the fluorescent probes – together into a space smaller than the width of the fiber. human hair, greatly increases their ability to interact.
“Our chip is unique in that it uses an electric field to clean nucleic acids from the sample and speed up a chemical reaction that tells us they are present,” said Santiago.
The team created its device with a meager budget of around $ 5,000. Currently, the DNA amplification step has to be done outside the chip, but Santiago hopes that within a few months his lab will integrate all the steps into a single chip.
Some human-scale diagnostic tests use similar gene and enzyme amplification techniques, but they are slower and more expensive than the new test, giving results in as little as 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 modified to detect the presence of other harmful bacteria, such as E coli in food or water samples, or tuberculosis and other blood diseases.
“If we want to look for another disease, we just need to design the right nucleic acid sequence on a computer and email it to a commercial manufacturer of synthetic RNA. They sent back a vial with a completely reconfigurable molecule of our assay for a new disease, ”Ramachandran said.
The researchers are working with Ford Motor Company to further integrate their steps and develop their prototype into a marketable product.
Reference: “Electrically controlled microfluidics for quick diagnosis based on CRISPR and its application for detection SARS-CoV-2”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, Proceedings of the National Academy of Sciences.
DOI: 10.1073 / pnas.2010254117