Cell free nucleic acids (cfNA) are genetic sequences that are not attached to cells and can be found circulating in the blood. cfNAs can be used to detect mutations in genetic sequences and can thereby be used as a ‘liquid biopsy’ tool for diagnosis of several types of cancer, replacing the necessity of invasive biopsy sampling of tissue. Researchers from University of Toronto have recently published a simple method of analyzing the amount of mutated cfNA present in patient blood.
The article, appearing in Nature Chemistry, details the fabrication of an electrochemical clamp assay targeted towards detecting mutations in the KRAS gene, which is known to cause lung, colorectal and ovarian cancer. The assay works by mixing in clamps that are specific for all other mutations except the mutation of interest, leading to a solution that has only the target mutation free of clamps. This solution is then applied to a sensor, where the target mutation binds, and is detected with the help of an electrochemical sensor. The other mutations which have been clamped are unable to bind to the sensor and are eventually washed away.
The electrochemical clamp assay has several advantages over existing methods of analysis of cfNAs, such as polymerase chain reaction (PCR). While maintaining the same level of accuracy, the test requires much less volumes of serum, and can be performed on undiluted serum, which leads to simplicity in workflow and minimized sample loss. Additionally, the test can produce results in as little as 5 minutes, and can cut down on significant costs involved in cancer diagnosis, due to its straightforward automation of a chip-based assay which will reduce the cost per test.
Study in Nature Chemistry: An electrochemical clamp assay for direct, rapid analysis of circulating nucleic acids in serum…
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