19 May 2004
CDs that contain blood samples rather than music could transform medical testing.
A BioCD developed by a team of Purdue University scientists may pave the way for while-you-wait blood tests that screen patients for the onset of thousands of diseases.
The current version of the Purdue BioCD is made by etching tracks (concentric circles) into a HeNe laser mirror. Antibodies are printed onto the tracks to bind to different disease marker proteins found in blood.
To conduct the tests, a sample of blood is placed on the BioCD which is spun, in the same way as a music CD spins in a stereo, in order to coat the tracks.
“Once the surface of the BioCD has been exposed to a blood serum sample, which would not need to be more than a single drop, you could read the disk with laser technology similar to what is found in conventional CD players,” explained David Nolte, the leader of the Purdue research team. “Instead of seeing digital data, the laser reader would see how concentrated a given protein had become on each track.”
At the moment, the team are using a beam from a HeNe laser to read the disc. The changes in the intensity of the reflected laser beam directly relate to the concentration of protein. Nolte says this technique can detect proteins with a sensitivity of just 10 ng/ml.
To date, the BioCD has five tracks, however in the future the team says that this could be expanded to 10,000 – each searching for a different protein. Despite the promise of BioCDs, Nolte says that they will not be available on the market anytime soon.
“While in principle they can be developed, significant work will need to be done to refine these techniques sufficiently,” he said. “It will be at least 10 years before doctors have BioCDs.”
Jacqueline Hewett is technology editor on Optics.org and Opto & Laser Europe magazine.
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