Two-dollar testing device detects Zika quickly

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The cartridge used in the device uses an assay that only requires a single temperature for a saliva sample, instead of multiple temperature changes in a traditional laboratory setting.(Credit: University of Pennsylvania)

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Concerns about the Zika virus seem to be spreading just as fast as the disease, but a new portable device could provide an accurate way to find and diagnose the disease at an extremely low cost. Scientists and engineers at the University of Pennsylvania have invented a new electricity-free test made from inexpensive materials, that could offer a reliable diagnosis in a short amount of time.

Utilizing an assay placed in a cartridge made by a 3D printer, the new test looks for genetic material from the Zika virus instead of antibodies produced by the body to combat the disease. Using antibodies to determine the presence of the Zika virus can often produce false results because the patients who have the virus may not have produced enough antibodies at the time of testing, or may have another disease that triggered the release of those antibodies.

The new test also uses a more efficient means of testing the molecular structure of the samples and the virus, through a technique called reverse transcription loop-mediated isothermal amplification (RT-LAMP). Traditional testing for genetic material often requires multiple copies and temperature changes in a laboratory to determine the presence of genetic material. The RT-LAMP process only requires the sample to be kept at one specific temperature. The new device use a "chemically-heated cup" to control the temperature without a need for electrical power and only costs approximately US$2 to produce, according to the study.

The test results can also be produced much quicker compared to traditional laboratory testing. A color-changing dye in the cylinder shows the presence of the virus, and the study says that scientists were able to obtain a diagnosis from a single sample in less than 40 minutes.

Haim Bau, a professor from the University of Pennsylvania's Department of Mechanical Engineering who co-authored the study, says further testing is needed to make sure that the new device and testing system match the "gold standard" of traditional diagnostic genetic testing.

"Our work represents a proof of concept at this stage," Bau said. "Before the assay can be adapted for medical use, we must experiment with patients' samples and make assure that our assay and system match the performance of the gold standard and operate reproducibly and reliably. We are fortunate to have dedicated colleagues in endemic regions ready to assist us in this task."

However, if the results are a success, the new testing device could provide another low-cost means of testing for the Zika virus in areas of the world where resources and access to electricity are scarce. Synthetic biologist James Collins from Harvard University's Wyss Institute led a team of researchers to create a testing device that uses a synthetic biomolecular sensor on a paper disc to test for the Zika virus' RNA sequence in blood, urine and saliva samples.

The study was published in the journal Analytical Chemistry.

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