NEW YORK, Sept. 8 (UPI) -- The CD drive and inkjet printer plugged into your personal computer someday could help produce cheap genetic tests and scan for individual molecules, researchers have discovered.
"There is a huge number of things we can test for -- the presence or absence of DNA, or infectious diseases," researcher Michael Burkart, a biological chemist at the University of California, San Diego, told United Press International. "We've been contacted by Third World countries who think it would be a perfect system to look for AIDS who don't ordinarily have money available to do so," he said.
"Another good application is (for) detecting bioterrorism," Burkart added. "People want to be assaying huge numbers of samples all over the country all day long. That can run up to a significant bill if one is trying to do it on expensive machines. For us to run our experiment, it (would) cost maybe $500."
The novel technique could help greatly empower scientists and ordinary people worldwide, experts note, enabling tests and research that now requires machines thousands of times more expensive than a simple CD player.
"It remains to be seen if the details can be worked out, but the concept is extraordinarily powerful," chemist M.G. Finn of the Scripps Research Institute in La Jolla, Calif., told UPI. "Home tests for cancer could become a reality. Inexpensive tests for performance-enhancing drugs or narcotics or explosives or anthrax might be possible. The list is endless."
The researchers hit upon the method in 1999 when co-researcher James La Clair, a molecular biologist with Bionic Bros GmbH in Berlin partnered with Burkart's lab, accidentally spilled lab chemicals on a compact disc. Science labs often rely on lasers to detect chemicals, and it made sense to design a way to scan molecules using the most commonplace laser on the planet -- the CD player.
"I was working on a technique called 'single molecule spectroscopy,' which requires a $200,000-to-$300,000 instrument, and I had a CD of music that I was going to listen to on my bench," La Clair told UPI. "And the single molecule spectroscopy machine used a fluorescent dye that I spilled on the CD and didn't notice. I put it in the CD player and it didn't play, and I took out the disk and noticed it was because I spilled dye on it. I realized the same dye used on $300,000 machines was being detected on my $100 CD player," he explained.
"The CD is by far the most common media format in our society on which to store and read information," La Clair said. "It's portable, you can drop it on the floor and it doesn't break, it's easy to mass-produce and it's inexpensive."
The researchers take standard inkjet printer cartridges and replace the ink inside with a solution containing molecules called ligands, which bind specifically to compounds of interest, such as DNA or proteins. The process works much as keys fit only certain locks. An inkjet printer then can print the ligands onto any CD as if they were simply just another color.
To run a molecular scan, such disks would be bathed in a test solution -- for instance, a blood test -- and cleaned. Then the disk would be read by a CD player.
The conventional CD is made of a layer of metal sandwiched between a layer of plastic and a protective lacquer coating. When a CD is "burned," as the process is called, a laser etches pits into the metal layer. CD players use lasers to read the series of pits and intervening smooth disc surface much as the needle on a phonograph player would run over grooves carved in wax. Instead of reading microcurves in record grooves, the CD translates microengravings into the ones and zeroes that make up bits of digital information.
The researchers' technique exploits the fact that anything marring the surface of a CD interferes with the CD player's laser's ability to read the data encoded on the disk.
"We are actually using the error to get our effect," Burkart said.
If the CD player notes errors while reading certain points on the disk, it signals that ligands have bound to their targets at those spots. A disk could contain as many as 250 different ligands, and "that can easily be doubled or multiplied by 10," Burkart explained.
"James has even done this with CDs (containing) music, like Beethoven's Fifth Symphony, and you can actually hear the errors," Burkart said.
"How many people on this planet can actually hear a molecule attached to another molecule?" La Clair asked. For more precise readings, the researchers have developed software that compares the data and errors on the disk before and after the test solution is applied.
The researchers will present their findings in print in the Sept. 21 issue of the journal Organic and Biomolecular Chemistry, with the online edition of the article now available on the journal's Web site. The patent on the method is held by the University of California, but the scientists hope that by publishing their research openly, others will customize the development, eventually leading to a wide range of inexpensive new diagnostic kits and other helpful products.
"I believe that this advance is highly welcomed because of its potential to make an inexpensive reader," said analytical chemist Richard Zare of Stanford University in California. Still, he added, "I would need to learn more than was contained in this article to determine the method's reliability and ultimate promise."
Although Finn said the advance would not be of much help to research practiced at well-funded laboratories, it could prove of enormous benefit "if you want to open certain kinds of scientific investigation to those without a lot of money -- and that's worth doing." He added: "It won't take much more development for it to become very interesting to my laboratory."
The researchers also will eventually release their software publicly under an open-source license.
"We're moving toward the possibility, not only to have users gain access to these tools, but to also open up the development of these tools to an open audience. It is our view that we really don't know what molecules people want to read," La Clair said.
"Jim and I both believe there's something of a global change as technology about molecules is concerned, and the ability to access this technology," said Burkart. "People are interested in molecules -- particularly their own molecules such as DNA, but also other molecules -- when eating food that is genetically engineered. There are all sorts of really sophisticated consumer electronics, but there's very little out there for people to go out and look at molecules -- home pregnancy kits and blood-glucose tests, but that's it. We think a major change is coming, and people will have access to this, and we're using an existing format that's ubiquitous: the CD player."
Finn emphasized that all the molecular tests Burkart and La Clair suggest are available now to some degree, "and putting them on CD won't necessarily make them better or faster. The difference is that now you usually need an expensive piece of equipment or two, and a different piece of equipment for each test. If you can do them with your home computer, it's a lot more convenient."
Obviously, there is a lot more work to be done, Finn commented. "They've just scratched the surface -- if you'll pardon the pun."
