The scientists said these sensors, designed to detect many cancerous proteins, could also distinguish the type of tumor, how it responds to treatment, and whether it has metastasized.
“We are trying to innovate in a context of making technology available to low- and middle-resource settings. Putting this diagnostic on paper is part of our goal of democratizing diagnostics and creating inexpensive technologies that can give you a fast answer at the point of care,” said Sangeeta Bhatia, a biomedical engineer at MIT and senior author of the study published on April 24 in Nature Nanotechnology.
Bhatia’s team had initially investigated the concept of detecting naturally occurring cancer biomarkers, such as proteins or circulating tumor cells, in the patient’s blood samples. However, these biomarkers are hard to find, especially at early stages, prompting the team to create “synthetic biomarkers” that could diagnose cancer by amplifying small-scale changes occurring within small tumors.
Nanoparticles previously created by the team can detect the activity of proteases, biological catalysts that can help tumor cells spread. However, since this equipment is not always available, the researchers developed new nanoparticle sensors that could be analyzed more easily and affordably using a technology that reads repetitive DNA sequences called CRISPR.
Specifically, the nanosensors are designed so that when they encounter a tumor, they shed short sequences of DNA that will eventually end up in the patient’s urine. The urine sample can be analyzed using a paper strip that recognizes a signal activated by a CRISPR enzyme called Cas12a. When a particular DNA “barcode” is present, Cas12a enhances the signal so it appears as a dark strip on the paper test.
In a study conducted in mice, the scientists showed that a panel of five DNA barcodes could accurately distinguish tumors that first arose in the lungs from tumors formed by colorectal cancer cells that had metastasized. The team also collaborated with other institutions to build a device to distinguish at least 46 DNA barcodes in a single sample.
The scientists said they are now working on further developing the nanoparticles, with the goal of testing them in humans.
