Video credit: Brock University
A chemist and a parasite expert at Brock University have teamed up to produce and test out a simple device that can detect diseases from DNA samples. It’s a scaled-down version of what is normally an expensive and complicated DNA laboratory technique, yet it’s fast, inexpensive, and accurate, making it ideal for use in developing countries.
Brock University assistant professor of chemistry Feng Li’s device consists of a strip of paper attached onto a glass slide. The paper contains several rows of what look like thermometers, lines with markings projecting out of bulb-like circles.
DNA samples are loaded onto the circles and move up the lines, much like mercury rises in a thermometer.
“Different concentrations of the genetic disease biomarkers in the samples would migrate different distances,” says Li. “So, all you need to do is read the distance they penetrate, just like you’d read a ruler.”
Known as the quantitative paper-based DNA reader, each device costs only about 10 cents. They work with a scaled-down version of a traditionally expensive and complex DNA laboratory technique known as polymerase chain reaction (PCR).
The PCR technique normally requires highly specialized equipment and expensive molecular probes. But Li’s device is able to read DNA samples through a PCR technique using simple technology and low-cost chemicals.
“This is going to be extremely useful in resource-limited settings where you don’t have a lot of facilities to interpret the results,” says Li.
Photo credit: Brock UniversityOne such setting is the National Autonomous University of Honduras, where Brock University professor of health sciences Ana Sanchez runs an internationally-renowned research program focusing on parasites.
She and her research team collected worms that had been expelled by children suspected of having soil-transmitted helminth infection, a disease affecting about 1.5 billion people worldwide and a major cause of childhood malnutrition and physical impairment.
The researchers used the quantitative paper-based DNA reader to test the worms for helminth infection.
“The results are beautiful; there’s no doubt that the system works,” says Sanchez.
She applauds the speed and sensitivity of the device, saying that diagnostic techniques in developing countries are traditional, basic and rely on the expertise of the person observing the sample.
Sanchez says the device goes beyond just a yes or no result by measuring the amount of genetic disease biomarkers in the DNA sample.
“How many parasites is this child harboring?” she says. “That tells you maybe their immune response and nutrition are impaired, that we'd need to consider if treatment needs to be ramped up, even if there could be a possibility of parasitic resistance.
“The knowledge of parasitic burden of individuals and community will directly lead to public health interventions. What Feng has proven is that his invention works. We’re ready to bring it to the field.”
The research team’s results are in their study “Paper-Based DNA Reader for Visualized Quantification of Soil-Transmitted Helminth Infections,” published Tuesday, Jan. 16 in the journal ACS Sensors. PhD student Alex Guan Wang and master’s student Tianyu Dong are the study’s first authors.
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