Shirin Khaliliazar, Fibre Technology
Textile and Paper Microfluidic Platforms for Electroanalytical Nucleic Acid Testing
In her dissertation, Shirin Khaliliazar presents techniques that could be used for manufacturing fast and reliable self-tests on paper and textile for infectious diseases such as COVID-19.
What is your research about?
"We have tried to develop miniaturized nucleic acid amplification diagnostic tests (NAATs), as home-based diagnostic tests, an alternative to PCR test, which now heavily relies on centralized laboratories. It’s a bit like pregnancy tests or alcohol tests for rapid and early disease diagnosis through genetic materials (DNA/RNA)," says Shirin Khaliliazar.
"Paper and textile benefit from outstanding features such as their capability to transfer solutions without the need for external tools like pumps. They are lightweight, disposable and due to their biocompatibility and porous network, we can store bioreagents for ready-to-do reactions. We have integrated electrical read-out to our microfluidic paper and textile-based DNA sensor that provides test results in digital forms, to show the positive or negative tests. It is not like colorimetric used in a pregnancy test, where it can be hard to see the test results with the naked eye."
"We used inexpensive materials and simple and easy techniques such as weaving and wax printing in our lab to show that we don’t need cleanroom infrastructure or trained personnel to make miniaturized diagnostic tests."
PCR (polymerase chain reaction) test is the gold-standard diagnostic test under the umbrella of nucleic acid amplification tests (NAATs). PCR is highly specific as it identifies specific genes assigned to pathogens in their genetic materials, unique for every species. Also, PCR is highly sensitive as it detects a single target gene and amplifies it to millions of copies to be easily detected.
"Due to this high sensitivity and specificity we can identify infected people in very early days of infection, compared to the common antigen tests, known as antibody tests. Antibody tests usually become valid after 7 to 10 days of the start of the symptoms. But PCR is not suitable for point-of-care applications as it requires bulky and expensive thermocyclers to perform the chain amplification reaction. The good news is that there are alternative methods called isothermal amplification technologies like RPA (recombinase polymerase amplification) that work at relatively low constant temperatures (37–42°C). With this technique, you can do the test by putting it under your arm, and your body heat is enough to conduct the test. We showed the possibility of combining the RPA in porous substrates with electrochemical detection methods that offer quantitative reliable test results. It is as easy as this that improves NAATs towards a home-based kit."
What difference could this make for patients or healthcare?
"It can both reduce costs and save time. PCR tests have to be sent to centralized clinical laboratories, which is a costly and time inefficient process. With this method, you don’t need any trained personnel or expensive instruments to conduct the tests. Also, you can easily dispose of the tests simply by burning them, without any environmental concerns," says Shirin Khaliliazar.
What is required for this method to become a product?
"We have demonstrated the potential of paper and textile as substrates to perform and facilitate sample preparation, DNA amplification and electrochemical detection as three main steps in nucleic acid amplification tests (NAATs). The next step is to put these three steps together and make fully integrated (sample-to-answer) paper-based or textile-based microfluidic NAATs and challenge these sample-to-answer tests for near the patient applications outside of clinical labs."
How did you become interested in this field?
"My Master’s thesis was about using biodegradable polymer for drug delivery and wound healing applications. Also, after working for almost two years as a research engineer in the same project and field, I realized my interest and passion for developing applicable products in the biomedical field. The idea of the work was to create a skin patch for infections that was antibacterial and, at the same time, wound healing. I got interested in this field and wanted to gain knowledge and skills in the diagnostics field as I realized that without a diagnosis, medicine is blind. We need to have the right diagnosis, and then medicine comes into practice."
Text: Sabina Fabrizi