You may hold the cure for cancer. We all may. Some believe it’s written in our genes and locked away in our cells. There are about 50 trillion cells in a human body; in each cell, as many as 25,000 different genes hold the formula – written in DNA – for every cell’s function, whether it’s a muscle cell, nerve cell, or a blood cell. Figure out which genes make the cell work, and you can recognize malfunctions that might lead to diseases such as cancer. Even better, you can potentially fix them.
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One of the best decoding tools at the disposal of geneticists and biologists is a microarray, a silicon or glass chip about 1.5 centimeters square printed with a grid of microscopic dots – tens, even hundreds, of thousands of dots, each one a different segment of synthetic DNA. Just as a pregnancy test will change color to indicate the presence of a particular hormone, the DNA spots on a microarray will glow to indicate the presence of specific genes. Researchers use microarrays to test samples of real DNA or RNA, to identify healthy as well as mutated genes, and to determine which genes are active in a cell. Although scientists can essentially perform thousands of experiments simultaneously on a single microarray, one device can cost upwards of $500 – and it can only be used once.
Microarrays cost a lot today because the conventional method for manufacturing them is highly complex. Typically, a computer-controlled robot uses techniques borrowed from photolithography to create strands of synthetic DNA by linking nucleotides in the appropriate sequences. This method usually involves 70 to 80 steps, so it can take up to a week to produce a single microarray.
But now a new technique, invented by a team of researchers led by assistant professor Francesco Stellacci in MIT’s Department of Materials Science and Engineering, could shorten microarray production time to mere hours and make DNA analysis as inexpensive and common as a blood test.
The technique, dubbed supramolecular nanostamping, begins with a microarray that has been manufactured by conventional means. But Stellacci, capitalizing on DNA’s natural ability to replicate, has devised a simple system for copying the original microarray (known as the master) in just six steps – instead of the typical 70 or 80 – to produce another microarray. The copy so closely resembles the master that it can be used to produce other arrays, exponentially increasing the production rate.
“The beauty of this process is that it can be scaled up,” says Stellacci. Currently, it takes him three and a half hours to produce one microarray. But he anticipates that in a manufacturing setting, it would be possible to produce hundreds in the same amount of time. That could significantly reduce production costs and make DNA microarrays accessible not only to laboratory geneticists but also to health-care providers, fundamentally changing the way doctors diagnose and treat diseases. For example, instead of running a series of blood tests to determine what ails you, a doctor could analyze hundreds of your genes in one step.