Researchers at Imperial College London and MIT have developed a simple cancer urine test based on injected gold nano-clusters which enter the urine only in the presence of cancer. So far, the researchers have used the test to detect colon cancer in mice. A positive result is indicated through a simple color change, meaning that the test could be ideal for rapid diagnosis in the field.
Finding cancer at an early stage can have a massive impact on treatment outcomes. However, many tests to achieve this can be invasive, expensive, and time consuming, and require a visit to a hospital or clinic. This makes routine screening difficult, especially for those who live in remote areas. A simple field test for cancer could help to increase screening and detection rates.
To address this, these researchers have developed this new test, requiring only an injection, followed by a visual assessment of a urine sample, which will change color if cancer is detected. The test is based on gold nanoclusters bound to protein carriers, which are injected into the blood.
Matrix metalloproteinases (MMPs) are enzymes that are highly active in many cancers. The researchers designed the bond between the gold-nanoclusters and the protein carriers to be cleavable by MMPs in the tumor microenvironment. This liberates the nanoclusters, which are small enough to pass through the kidneys and enter the urine.
Treating the urine sample with hydrogen peroxide and a chemical substrate results in a blue color change if the nanoclusters are present in the sample. The researchers can make the nanocluster/protein complexes sensitive to specific MMPs which are upregulated in specific cancers. For instance, MMP9 is upregulated in colon tumors, and the researchers have tested an MMP-9 sensitive version of their system in mice bearing such tumors.
They found that the tested urine turned blue only in mice bearing colon tumors, suggesting that the test is sensitive enough to accurately diagnose colon cancer. “By taking advantage of a chemical reaction that produces a color change, this test can be administered without the need for expensive and hard-to-use lab instruments,” said Molly Stevens, one of the researchers involved in the study. “The simple readout could potentially be captured by a smartphone picture and transmitted to remote caregivers to connect patients to treatment.”
Study in Nature Nanotechnology: Renal clearable catalytic gold nanoclusters for in vivo disease monitoring