As seen with the COVID-19 pandemic, rapid, simple, accurate, and sensitive assays are critical for detecting viral pathogens and controlling the spread of infectious diseases. Unfortunately, laboratory-based methods often require highly trained personnel and involve complex procedures. In a new study, researchers at the University of Illinois at Urbana-Champaign combined their efforts to develop a device that clips onto a smartphone to quickly detect Zika virus in a drop of blood.
Zika virus mainly through Aedes aegypti Mosquito. While the disease is largely asymptomatic or causes mild symptoms in adults, it can cause developmental disorders in newborns if their mothers become infected early in pregnancy. Currently, the virus is spreading in more than 87 countries, infecting thousands of people each year, so better detection and control measures are needed.
“Mosquito-borne viruses can cause serious illness, but they have similar symptoms. If you have Zika, malaria, dengue or chikungunya, you may go to the doctor with a fever and they won’t know why,” said Bu Said Ryan Cunningham (CGD Director/MMG), Chair of Electrical and Computer Engineering at the Intel Alumni Foundation. “But it’s important to know if it’s Zika, especially if the patient is a pregnant woman, because the consequences for the developing fetus are very serious.”
Zika virus infection is currently detected by polymerase chain reaction tests performed in the laboratory, which amplify the virus’ genetic material, allowing scientists to detect it. In the new study, the researchers used cycle-mediated isothermal amplification to detect the virus in blood samples, a method suitable for use in point-of-care clinics. While PCR requires 20-40 repeated temperature changes to amplify genetic material, LAMP requires only one temperature – 65°C – making it more manageable. Additionally, PCR tests are very sensitive to the presence of contaminants, especially other components in blood samples. Therefore, samples are first purified before use. LAMP, on the other hand, does not require any such purification steps.
Insert the cartridge containing the reagents needed to detect the virus into the instrument to perform the test while clipping the instrument to the smartphone. Once a patient adds a drop of blood, a set of chemicals destroys the virus and blood cells within five minutes. A heater under the cartridge heats it to 65 °C. A second set of chemicals then amplifies the viral genetic material, and if the blood sample contains Zika, the fluid inside the cartridge fluoresces bright green. The whole process takes 25 minutes.
“Another cool aspect is that we’re using smartphones to take readings,” Cunningham said. “We designed a clip-on device so that the smartphone’s rear camera sees the cartridge as it zooms in. When there is a positive reaction, you see a small bloom of green fluorescence that eventually fills the entire cartridge with green light.”
Researchers are now developing similar devices to detect other mosquito-borne viruses at the same time, and are working to make the devices even smaller. “While our clip-on detector is very small, a lot of space is taken up by the battery. In the next version, it will be powered by the phone’s battery,” Cunningham said.
Study “Smartphone clip-on instrument and microfluidic processor for rapid sample-to-answer detection of Zika virus in whole blood using spatial RT-LAMP” is published in the journal analyst Available at 10.1039/d2an00438k.
This work was conducted in collaboration with Rashid Bashir (CGD/M-CELS), Abel Bliss Professor of Engineering; Enrique Valera, Research Assistant Professor of Bioengineering; Minh Do, Thomas and Margaret Huang Professor of Electrical and Computer Engineering; and Professor of Electrical and Computer Engineering William King. The research was funded by the National Institutes of Health and the National Science Foundation Innovation Partnership.