The old test directly measured the amount of PSA in the blood. The new nanoparticle test will indirectly measure PSA levels.
For this procedure, two types of nanoparticles are added to a man's blood sample. First, spherical gold nanoparticles tipped with antibodies bind to one side of the PSA proteins. Next, magnetic nanoparticles bind to the other side, basically sandwiching the PSA.
A magnet then draws the PSA and nanoparticle sandwich out of the blood. The nanoparticles then separate, which in turn can spur the release thousands of DNA strands.
Since every single PSA particle can result in thousands of DNA pieces, even the tiniest amounts of PSA can be easily detected. Compared with the existing PSA blood tests, this new method is 300 percent more sensitive.
Typically, a patient who undergoes prostate surgery may have to wait up to seven years before he definitively knows whether he is cancer free. The new test would shave years off that wait.
PSA, however, isn't even an ideal marker for early stage prostate cancer, says Shana Kelley, a scientist building nanostructures for disease diagnosis at the University of Toronto. "To get an elevated PSA level that we can detect usually means (a patient) already has a good sized tumor," said Kelley.