DNA Bingo

The tiny dots in this array are only 8 millionths of an inch (200 nanometers) wide, and each contains distinct strands of DNA.  Used to diagnose certain diseases, DNA microarrays may become more available because of a new "nano-printing" technique.

With up to 500,000 dots on a single silicon or glass chip, microarrays can quickly analyze a DNA sample.  If some part of the sample matches the genetic code in one of the dots, the two DNA molecules will stick together, causing the dot to light up.

Like a genetic bingo card, a doctor or researcher can screen a person's DNA for Alzheimer's and certain types of cancer.  The technique can also identify viral infections like AIDS.

The widespread use of DNA microarrays is hampered by the fact that producing them is a painstaking process that involves at least 400 printing steps and costs approximately $500 per microarray.

A novel method, called Supramolecular Nano-Stamping (SuNS), starts with the desired pattern "written" in DNA and then essentially lets other DNA-bits assemble themselves into an exact copy.

Developed at MIT, this nano-sized copy machine requires only three steps and could reduce the cost of each microarray to under $50.

Various materials besides DNA can be made to assemble along an original DNA "master," so SuNS has the potential to print out other nano-devices - like tiny metal wires, single-electron transistors, and biosensors.

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 -- Michael Schirber

Credit: Francesco Stellacci and Arum Amy Yu