August 21, 2003
CD Player Turned Into Bioassay Molecule Detection Instrument

Scientists at the University of California at San Diego have adapted an inkjet printer and a CD player to make a scientific instrument that detects types of proteins molecules present in a solution by measuring where they bind on the surface of a specially prepared CD.

To do molecular screening, the researchers took a CD encoded with digital data, and enhanced the chemical reactivity of the plastic on the readable surface. They then added molecules they wanted to attach to this surface to the empty ink wells of an inkjet printer cartridge and used the printer to “print” the molecules onto the CD. This resulted in a CD with molecules bound to its readable surface in specific locations relative to the pits in the metal layer of the CD encoding the digital information. When the CD with these molecules attached is placed in a CD player, the laser detects a small error in the digital code relative to what is read from the CD without the molecules attached.

To detect proteins or other large molecules in a solution like a blood sample, the modified CD is allowed to react with the sample solution. Like a key that only fits in a certain lock, some proteins bind to specific target molecules. Thus, specific molecules on the surface of a CD can be used to “go fishing” for certain proteins in a sample. The attachment of these proteins will introduce further errors into the reading of the CD. Furthermore, since the molecules on the surface of the CD are at known locations relative to the bits of encoded information, the errors tell the researchers what molecules have attached to their target protein and, thus, whether or not that protein is present in the sample.

“James has even done this using CDs with music, like Beethoven’s Fifth Symphony,” says Burkart. “And you can actually hear the errors.”

“How many people on this planet can actually hear a molecule attached to another molecule?” asks La Clair.

While a few bugs need to be ironed out before the technique can be used to accurately quantify the amount of a given protein in solution, Burkart plans to apply it immediately to help him screen for new compounds in his natural products chemistry research laboratory. Compared to the $100,000 price tag for a fluorescent protein chip reader, he points out, a CD player costs as little as $25.

The researchers envision many other potential applications for this technology outside the laboratory, particularly in the development of inexpensive medical diagnostic tests, now beyond the means of many people around the world, particularly in developing countries.

“In theory, anyone who has a computer with a CD drive could do medical tests in their own home,” says La Clair.

Basically, they use an inkjet printer cartridge to put different kinds of molecules at differnet locations on the CD. Each kind of molecule has affinity for a different type of target protein molecule. Then they expose the CD to a solution that has unknown assortment of proteins. Those proteins with affinity for specific places on the CD bind in those places and then when the CD is read the signal in those areas is changed by the addition of the larger proteins that have bound to the molecules which have been anchored to the CD.

This work demonstrates how advances in electronic technology are helping to lower the cost and increasing the speed of doing biomedical research and clinical testing. This is not the first use of inkjet printer technology as tools for doing biomedical research. See Modified Printers Used For Tissue Engineering and STMicro Releases Silicon DNA Analysis Chip for other examples.

Share |      Randall Parker, 2003 August 21 03:00 PM  Biotech Assay Tools

Patrick said at August 21, 2003 4:45 PM:

You could also use that same tech to analyse DNA, which is after all just a very long protein molecule. A computer with a CD drive plus the right software and a prepared CD and you could sequence someones DNA? Maybe.

Bob said at August 22, 2003 4:41 PM:

I love this stuff; it's almost like a Gene Roddenberry plot: "If we divert power from life support and hook a tricorder into the main relay on deck seventeen we should be able to extend the range of long range sensors by another 15%..."

Max Leibman said at August 24, 2003 3:53 PM:

I was thinking more MacGuyver than Roddenberry, but it works that way, too.

I'll have to show this to my roommate. He's always repurposing electronics to make testing equipment and spare parts for other electronics. This might inspire him to set his sights higher.

Grady said at September 8, 2003 8:18 PM:

Patrick, DNA is not a very long protein molecule. DNA is made of nucleic acids and ribose, proteins are made of amino acids.
But you're right that you could, if you wanted to, use the same technique for DNA. Sequencing would require an indirect approach, however, because single base pair interactions aren't very strong. You Would probe for longer sequences, probably.

JLaClair said at September 19, 2003 10:35 AM:

What molecule would u want to read?

Randall Parker said at September 19, 2003 10:50 AM:

James, I'd want to read a molecule that makes a good melodic sound.

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