Engineers detect rare proteins in blood through cellphone camera

Detecting rare proteins in blood can save many lives but they are difficult and expensive to do so. However, according to a new study, engineers can now detect them simply with the help of a cellphone camera.

Engineers at the University of Pennsylvania have developed a unique test that makes use of off-the-shelf components and can detect single proteins with result within minutes, as compared to the traditional expensive and bulky workflow that takes several days.

With the help of a standard mobile camera and some strobing LED lights, along with the lab’s microfluidic droplet generators, researchers were able to develop a system which is a thousand times more sensitive than the standard protein tests. It is handheld and also comparatively less costly than the current state-of-the-art single-protein tests, as per the university’s blog.

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“By a thousand times more sensitive, we mean that if we had a vial of blood with only a few of the relevant proteins, we can accurately count those proteins, whereas a traditional test couldn’t reliably tell the difference between that vial of blood and one with none of the protein in it,” said lead researcher David Issadore.

The standard protein detection assay, ELISA, involves attaching antibodies to the proteins and then measuring how much the sample’s color changes in response to enzymes linked to the antibodies. The process is rapid and simple enough to be integrated in point-of-care devices such as home HIV tests.

The approach works by calculation one protein at a time by breaking apart the sample into microdroplets. Rather than having a single channel, the team flow droplets into hundreds of channels that pass by the camera at the same time. Encoding the strobing light with a signal further allowed them to tease apart one microdroplet from its neighbor, hence avoid overlapping over one another.

“We’re strobing the light in a very specific pattern that never repeats itself, which is a technique we borrowed from radar,” Issadore says. “As the signals are going across the screen they get imprinted with this barcode. So even though they overlap with one another, we can tell them apart by which strobe pulse illuminated each droplet.”