A team of researchers are working to develop an instrument that can be clipped onto a smartphone to rapidly test for Zika virus with a single droplet of blood.
Zika virus infections are currently detected through polymerase chain reaction tests performed in a laboratory, which can amplify the genetic material of the virus, allowing scientists to detect it.
“We have designed a clip-on device so that the smartphone’s rear camera is looking at the cartridge while the amplification occurs,” said Brian Cunningham from the University of Illinois at Urbana-Champaign in the US.
When there’s a positive reaction, you see little green blooms of fluorescence that eventually fill up the entire cartridge with green light,” Cunningham added.
In the new study, researchers used Loop-Mediated Isothermal Amplification to detect the virus in the blood samples using an approach suitable for point-of-care clinics. While PCR requires 20-40 repeated temperature shifts to amplify the genetic material, LAMP only requires one temperature — 65-degree Celcius — making it easier to control.
Additionally, PCR tests are very sensitive to contaminants, especially the other components in a blood sample. As a result, the sample is first purified before it can be used. On the other hand, LAMP does not require any such purification step.
A cartridge, that contains reagents required to detect the virus, is inserted into the instrument to perform the test while the instrument is clipped onto a smartphone.
Once the patient adds a drop of blood, one set of chemicals break open the viruses and the blood cells within five minutes. A heater below the cartridge heats it up to 65 degrees Celcius.
The second set of chemicals then amplifies the viral genetic material, and the liquid inside the cartridge fluoresces bright green if the blood sample contains the Zika virus. The entire process takes 25 minutes.
The researchers are now developing similar devices to detect other mosquito-borne viruses simultaneously and are working on making the devices even smaller.