Move Over, ELISA – There’s a New Test in Town

Every year, 36,000 men in the UK are diagnosed with prostate cancer. Having the cancer surgically removed can be a very painful process, both physically and emotionally. One can only imagine how it would feel to have undergone such a procedure only to be told that its success is uncertain. Yet this is a sad reality for thousands of men– current tests such as ELISA (Enzyme-Linked ImmunoSorbant Assay) cannot reliably diagnose the early recurrence of cancers. But now, a new test developed at Imperial College promises significantly earlier detection.

“The test is many orders of magnitude better than ELISA, the current gold standard,” says Professor Molly Stevens, who led the study. “Much better for when you want to diagnose samples that are very tiny in terms of the amount of marker present, for example a cancer recurrence.”

The new test works in much the same way as ELISA, looking for “biomarkers” of particular conditions. A biomarker is a molecule whose presence indicates a particular disease or virus – for prostate cancer, the biomarker is “Prostate Specific Antigen” (PSA).

The new technique detects PSA using nanoscopic gold stars, “nanostars”, coated in antibodies. These antibodies will bind to any PSA they come into contact with. Secondary antibodies, which have enzymes on them, then attach themselves to the primary antibodies. In small amounts, the enzyme creates a silver coating on the gold nanostars. This silver can then be easily seen on ordinary optical microscopes, showing exactly how much PSA is present in the sample.

The new technique was demonstrated for PSA but could, in theory, detect most diseases and viruses. According to Professor Molly Stevens, “We should be able to detect for any protein that you can routinely detect for with ELISA, which is any protein that can be recognised by an antibody – pretty much everything.”

The new test is nine orders of magnitude more sensitive than ELISA, and could be performed on any blood sample. On paper, it looks great – but when might we see it in clinical use?

“It’s hard to say because it depends on pairing up with an industrial company or partners, so that may take more or less time,” says Stevens. “There are some steps that we need to work out from a scientific viewpoint in terms of getting it from a lab prototype into a functioning device. We’d need at least a few years, as more research is needed.”

As thousands of cancer patients live in fear of remission, we can only hope that such tests can be developed sooner rather than later.

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