WASHINGTON (Commodity Online): Apart from adding glitter to women’s beauty, gold is helping scientists in several ways nowadays. In a recent development, researchers have used gold nanoparticles to detect prostate specific antigen (PSA), a protein associated with prostate cancer.

With the help of this new technology, the recurrence of prostate cancer could soon be spotted years earlier. The US and Australian team of researchers’ bio-barcode assay uses gold nanoparticles and DNA as amplification agents to detect prostate specific antigen (PSA), and it is 300 times more sensitive than other commercial assays.

Levels of PSA in patients who have had the prostate gland surgically removed typically drop to a level that is undetectable using conventional assays. If levels begin to creep up post-surgery, it can give physicians a warning that the cancer is returning - but only if they can detect this rise. With the new bio-barcode assay, PSA can be measured and monitored at much lower levels than current commercial immunoassays, and can therefore be used as a disease-marker.

The immunoassay is made of two components, a PSA antibody-functionalised gold nanoparticle decorated with DNA strands, and a magnetic microparticle functionalised with a second PSA antibody. In solution, these two particles both bind to PSA, sandwiching the protein between them. The sandwiched probes can then be magnetically separated thanks to the presence of the magnetic particle. The DNA that decorates the gold nanoparticles is then removed and detected using a scanometric assay, indicating how many sandwiched probes were formed and thus the level of PSA present in the sample. Hundreds of DNA strands are released for every molecule of PSA sandwiched in the assay, which helps boost the sensitivity of the test.

Chad Mirkin, who led the research at Northwestern University in Chicago, US, says this barcode assay was made possible by over a decade of work aimed at making polyvalent oligonucleotide nanoparticle conjugates. “Our ability to make gold particles functionalised with DNA and proteins, where the precise number of proteins and DNA strands can be controlled, allows us to create systems capable of amplification in the context of biodetection assays.”

The team tested their new technique on samples from 18 post-surgery patients, and detected low levels of PSA which would probably have been missed using existing measures. “It is the only tool out there that allows one to reliably measure PSA values in folks who have had their prostates removed,” says Mirkin.

According to Mirkin, the technology will be also useful in validating experimental therapies for prostate cancer because a person’s PSA levels can now be tracked in response to hormone, radiation and chemotherapy. However, Bock cautions that an extensive clinical trial is required to establish a compelling clinical application of high-sensitivity PSA assays.

Post your comment  (0)

Connect:

Post to Twitter

Post to Facebook