Brock researchers develop DNA reader

Brock University

Brock researchers have made a major new development in DNA disease detection, all with the use of a strip of paper.

Dr. Feng Li, assistant chemistry professor at Brock, and his colleague Dr. Ana Sanchez, Brock Health Sciences professor, have teamed up to create and test a new disease detection DNA method. Their method is cheap, quick and accurate, making it exceptionally beneficial to use in developing countries where expensive equipment is not as easily come-by.

The method works by dropping DNA samples on a special type of paper with tracks that have a circle at one end. The sample is dropped on the circle and travels up the line in the paper, like a thermometer. By measuring how far up the track a sample traveled, researchers can determine the concentration of biomarkers of genetic diseases in the sample. Each device costs approximately 10 cents.

Another cost efficient part of the process is Li’s PCR method. PCR, or Polymerase Chain Reaction, is used by researchers and health care workers to replicate a section of DNA millions of times. The process is typically accomplished through a complex repetitive heating and cooling process, initiating temperature-induced reactions in the DNA. Primers, which are short strands of DNA which are needed for replication, are added to the target DNA. DNA cannot replicate without having something to attach to, so the primer’s job is to be a base for new nucleotides to attach and replicate. Next, heating allows for DNA melting, the separation process of the double helix structure of DNA. After this, the sample is cooled, allowing the primer to attach to the separated DNA strands, and subsequently allowing for nucleotides in the sample to attach to the primer, completing a new double helix structure and thus forming two separate strands of DNA from one original one. The process can be done as many times as is needed to allow researchers and health workers enough copies of the DNA sequence for testing.

Li’s method of PCR uses cheaper chemicals and simpler technology to achieve the same results. In the study, researchers used a portable thermal cycler, a less expensive machine for the PCR process. The study was a collaborative effort with Dr. Sanchez, who runs a parasite-focused research program at the National Autonomous University of Honduras.

The study was focused on soil-transmitted helminth infection (STH), a disease caused by parasitic worms. It spreads in areas of poor sanitation, and affects approximately 1.5 billion people. The infection causes both nutritional and physical impairment. The parasites feed on human tissues including blood, which can result in depleted iron and protein levels, which can resulting in anaemia. The worms can also compete for vitamins in the digestive system and impair the body’s ability to absorb nutrients.

Researchers collected parasites from infected children in a rural region of Honduras who had been treated for their infections. They then brought the worms back to the lab and used their quantitative paper-based DNA reader (qPDR), the DNA disease detection method they had developed, to test the worms for presence of STH.

Li and Sanchez were delighted with the results. Their qPDR method worked accurately and efficiently. The simplicity of the method has several advantages, including accessibility and readability. Having a method where an expert can easily read the results rather than interpreting computed data, which can be expensive, is especially desirable in developing regions such as Honduras, where accessibility to highly technological systems and methods is not realistic.

Additionally, the test reveals the concentration of parasites, which can be incredibly helpful when treating infected children. Knowing how many parasites are living in a child can give indications to how they are being affected, and how severely.

The results of Li and Sanchez’s study were published on January 16 in ACS Sensors; the paper is entitled “Paper-Based DNA Reader for Visualized Quantification of Soil-Transmitted Helminth Infections.” Li is hoping to work with BioLinc in the near future to develop a plastic container that will house the DNA reader.

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