A revolution in medical testing will soon come to a doctor's office near you, thanks to a simple CD player. A team of Purdue University scientists led by physicist David Nolte devised a method to create analog CDs which will be able to screen thousands of proteins in your blood for potential diseases while you wait. You will no longer have to wait for weeks before getting the results provided by a specialized lab. Still, expect a few years before this technology comes to your physician's office. In "BioCDS could hit No. 1 on doctors' charts," Nolte says that "it will be at least 10 years before doctors have Bio-CDs at their disposal."
Here are some excerpts from this Purdue University news release.
While-you-wait medical tests that screen patients for thousands of disease markers could be possible with compact-disk technology patented by Purdue University scientists.
A team led by physicist David Nolte has pioneered a method of creating analog CDs that can function as inexpensive diagnostic tools for protein detection. Because the concentration of certain proteins in the bloodstream can indicate the onset of many diseases, a cheap and fast method of detecting these biological molecules would be a welcome addition to any doctor's office. But with current technology, blood samples are sent to laboratories for analysis -- a procedure that only screens for a few of the thousands of proteins in the blood and also is costly and time-consuming.
"This technology could revolutionize medical testing," said Nolte, who is a professor of physics in Purdue's School of Science. "We have patented the concept of a 'bio-optical CD,' which could be a sensitive and high-speed analog sensor of biomolecules. Technology based on this concept could provide hospitals with a fast, easy way to monitor patient health."
Here is how this new technology works.
CDs ordinarily store digital information -- such as computer data or music -- as billions of tiny "pits" in their surface. These microscopic pits, which represent binary ones or zeroes depending on their size, are etched in concentric tracks circling the midpoint from the inner to the outer edge of a CD.
Blood contains more than 10,000 proteins that physicians would like to monitor, and Nolte said up to 10,000 tracks on a CD could be paired up with a different protein.
"Each ring of pits, or 'track,' on the CD could be coated with a different protein," he said. "Once the surface of a BioCD has been exposed to a blood serum sample -- which would not need to be larger than a single drop -- you could read the disk with laser technology similar to what is found in conventional CD players. Instead of seeing digital data, the laser reader would see how concentrated a given protein had become on each track."
Below are illustrations and other references about how the BioCD works.
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Here you can see the Bio-CD mounted on a photoresist spinner (Credit: David Nolte). |
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And here is an antibody molecule attached to a BioCD for selective detection of antigen and blood proteins (Credit: David Nolte). |
And in this movie (39 seconds), Purdue physics professor David Nolte describes how his BioCDs will help medical providers conduct tests in the office rather than a lab.
This sure looks promising. So what's the current status and when will see these BioCDs in our doctors' hands?
The team's most recent experiments demonstrate a sensitivity of 10 nanograms per milliliter with a selectivity greater than 10,000. These numbers are sufficient to make a working prototype BioCD seeking biologically relevant molecules.
"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 Bio-CDs at their disposal, and that assumes everything goes smoothly in the interim."
This bio-optical compact disk system is patented since February 3, 2004. You can use this search engine of the U.S. Patent Office and enter the number 6,685,885 for more details.
Here is the abstract.
A device for identifying analytes in a biological sample, including a substrate having a surface lying substantially in a first plane, a plurality of targets, each having a wall lying substantially in a second plane offset from the first plane, and a receptor coating applied to one of the surface and the target walls for binding analytes present in the biological sample when the biological sample is applied to the substrate. A laser beam is sequentially directed onto each of the plurality of target, the laser being positioned relative to the substrate such that when the beam is directed onto a target, a first half of the beam is reflected back to the laser from the wall of the target and a second half of the beam is reflected back to the laser from the surface of the substrate adjacent the target. The laser combines the first and second reflected halves to produce a diffraction signal that has a first value when an analyte is not bound to the receptor coating associated with a target and a second value when an analyte is bound to the receptor coating associated with the target, thereby indicating the presence of the analyte.
And for more technical information about the BioCD, you can read these papers, "High-Speed Label-Free Multi-Analyte Detection through Micro-interferometry" (PDF format, 7 pages, 2.55 MB), "Spinning-disk self-referencing interferometry of antigen–antibody recognition" (PDF format, 3 pages, 859 KB) or "High-speed label-free detection by spinning-disk micro-interferometry" (PDF format, 6 pages, 402 KB).
Sources: Purdue University news release, May 18, 2004, via EurekAlert!; and various websites
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