Paper test strip detects cancer in minutes

New tech out of MIT could make cancer diagnostic devices as simple as pregnancy tests.

In places with little medical infrastructure, mammograms and colonoscopies can be too costly to implement. Yet, cancer deaths in developing countries account for 70 percent of cancer mortality worldwide. 

So a team led by MIT's Sangeeta Bhatia developed a cheap paper diagnostic (pictured) that works like a pregnancy test, revealing whether a person has cancer based on a urine sample -- with results in minutes. 

The technology relies on nanoparticles that interact with tumor proteins, which trigger the release of biomarkers that can be detected in urine. Specifically, we're talking about tumor proteins called matrix metalloproteinases (MMPs), which help cancer cells escape by cutting through the proteins that hold the cancer cells in place. After these proteins are cut, the fragments accumulate in the kidneys and are then excreted in urine. Problem is, MMP signals are hard to detect on their own. 

  • To amplify signals from MMPs, the team coated nanoparticles with fragments of the proteins that are targeted by MMPs. (These short protein fragments are called peptides.) 
  • These nanoparticles group around tumor sites where MMPs are cutting up hundreds of peptides. When MMPs come across these nanoparticles, they cut off a part of the biomarker. 
  • To make it readily available in the developing world, the team adapted their nanoparticles to be analyzed on paper using a method called lateral flow assay -- the same tech used in pregnancy tests.
  • To create these test strips, they coated nitrocellulose paper with antibodies that can capture the peptides. 
  • These nanoparticles would be injected into high-risk patients with history of cancer before they're asked to urinate onto the paper strip. 
  • Once the peptides are captured by the antibodies, they flow along the strip and are exposed to several invisible test lines made of other antibodies that are specific to different tags attached to the peptides. 
  • If one of these lines becomes visible, it means the target peptide is present in the sample, and that cancer tissue is present in the body. 

In tests with mice, the researchers accurately identified colon tumors as well as blood clots, a possible sign of cardiovascular disease. The team is developing a business plan for a startup to commercialize the technology and perform clinical trials. 

But even with cheap diagnostic tools, many still lack access to adequate treatment. "There's something very unfair and troubling if we're able to tell people that they might have serious diseases and there's nothing that can be done about that," UC Berkeley's Lina Nilsson tells New Scientist. "If we're pushing out diagnostics, then the ability to treat should also be at the same places."

The work is described in the Proceedings of the National Academy of Sciences this week. 

[MIT News Office]

Image: Bryce Vickmark

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