Researchers of Howard Hughes Medical Institute (United States) have created a simple and non-invasive urine test that, tested in experimental models, changes its color when it detects the presence of colon cancer.
Technology, published in the magazine Nature Nanotechnology, It is in an initial stage of development and works by injecting in mice with this tumor nanosensors, which are fractionated by enzymes known as proteases that pass through the kidney and stain the color of urine blue, something that does not occur when injected in healthy rodents.
“By taking advantage of a chemical reaction that produces a color change, this test can be administered without the need for expensive and difficult-to-use laboratory instruments,” the researchers say.
When tumors grow and spread they usually produce biomarkers, used to detect and track cancer. However, not all biomarkers play an active role in tumor growth, and most are present in such small amounts that they can be difficult to find.
A family of tumor proteins known as matrix metalloproteases (MMPs) has drawn attention as possible biomarkers, as they help promote the growth and spread of tumors. Many types of cancer, including colon cancer, produce high levels of several MMP enzymes, including one called MMP9.
In this study, the team developed nanosensors where ultra-small gold nanoclusters (AuNC) were connected to a protein carrier through broken links by MMP9s. To develop the urine test that changes color, the researchers used two AuNC properties: its small size and its ability to cause a blue color change when treated with a chemical substrate and hydrogen peroxide.
The scientists also designed the AuNC protein complexes to dismantle after being fractionated by MMP in the tumor microenvironment or in the blood. When broken, the released AuNCs travel through the blood and are small enough to seep through the kidneys into the urine.
In healthy experimental models without high levels of MMP, the complexes remain intact and are too large to pass into the urine. Now, if the AuNCs have concentrated in the urine, a chemical test will produce a blue color change that is visible to the naked eye.
In this way, experts showed that their color change test could accurately detect, and in only half an hour, which urine samples came from subjects with colon cancer. During a four-week follow-up after the administration of nanosensors, individuals showed no signs of side effects, and there was no evidence that the protein-sensor complex or AuNC remained in the body.