Lab on a chip to detect Ebola virus

A new paper diagnostic device can detect Ebola and other viral hemorrhagic fevers in about 10 minutes. The device has silver nanoparticles of different colors that indicate different diseases. On the left is the unused device, opened to reveal the contents inside. On the right, the device has been used for diagnosis; the colored bands show positive tests. Credits: Jose Gomez-Marquez, Helena de Puig, and Chun-Wan Yen

Researchers at MIT have created a lab on a chip to detect hemorrhagic viruses, including the Ebola one.

These viruses are highly contagious and it is essential to prevent contamination, thus isolating immediately patients hit by these viruses. The problem is that today the diagnostic test to detect Ebola and its siblings may take a day.

Here is the value of the lab on chip developed at MIT: it can detect the presence of the virus in just 10 minutes.

What I called lab on a chip is actually a very simplified version, more similar to a pregnancy test. As is a pregnancy test the paper strip is absorbing a fluid (in this case a drop of blood, in the pregnancy test a drop of urine). This latter reacts with silver nanoparticles that have been characterized by virus specific antibodies. If a virus is present it sticks to the antibody and this makes the nanoparticle visible. Depending on the size of the nanoparticle (the same principle of quantum dot displays) a specific light wavelength is reflected, hence a specific color will appear on the paper strip.

By associating different antibodies to different sized nanoparticle the researchers have been able to create a single test that detects, and differentiate, Ebola, dengue and yellow fever viruses. In case of Ebola a red band will appear, a green one for dengue and a yellow one for the yellow fever.

This is yet another examples of cross fertilization of different technologies, specifically nanoparticles, antibodies and fluidic, that are coming together to become useful a a new field.

Researchers are now waiting for the FDA approval for the paper lab to be used in the field.  They are saying that the target is fast triage, if more certain diagnoses is needed a usual PCR (Polymerase Chain Reaction) test can be performed. That will take one or two days (and in several areas no lab is available for testing) and isolation procedures can be enforced immediately waiting for final confirmation.

 An interesting, although marginal twist, is that researchers are proposing to use a cell phone to read the colors, to help those who are color blind (and to detect unclear colors).  In this case the result will appear through an app directly on the cell phone screen when a photo of the paper strip is taken.  I can imagine this  kind of result evaluation occurring for several other tests that will be developed in the coming year, exploiting these technologies and the growing capability to manage nanoparticles at very low cost.

 

Author - Roberto Saracco

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