Building a Cell on Silicon

Cells are complex structures, making them difficult to replicate in the lab. But a team of Israeli scientists have taken a step in that direction by engineering a silicon chip that can produce proteins from DNA, the most basic function of life.

The system, which was designed to be relatively simple, suggests a path to mimicking life with partly manufactured components, according to an article from MIT Technology Review. Roy Bar-Ziv, a materials scientist at the Weizmann Institute of Science in Israel and leader of the work, called his cell-on-a-chip "a new system allowing us to examine how genes are turned on and off outside the living cell." This could go far in understanding of gene expression.

DNA fluoresces in the red squares positioned within circular compartments on a silicon chip, which imitate a cell's mechanism for gene expression. Image from the Weizmann Institute of Science.

Cells are constantly making proteins from instructions coded in DNA sequences. This process is controlled by other genes, often through complicated feedback. Bar-Ziv's new system will allow scientists to examine how these genes are controlled outside the living cell.

The chips were designed using a technique Bar-Ziv's lab developed several years ago to anchor DNA to silicon, by first coating the surface with a light-activated chemical. The lab used patterns of light to create spots where DNA binds and assembles into bundles. Each DNA bundle was confined to a small, round compartment. These compartments were joined by a narrow capillary about 20 micrometers wide to a larger channel, which carries a flow of liquid extracts from bacterial cells. Together, these formulate all the ingredients needed to synthesize protein from the DNA bundles.

The system allowed researchers to create a simple network of interacting genes, which could prove to be a significant step toward to the creation of artificial cells. In the past, scientists have easily synthesized proteins from DNA in a test tube, but those reactions would eventually fizzle out as proteins accumulate and synthesis slows, making it hard to create functioning genetic circuits outside of cells.

Bar-Ziv says that his system overcomes that problem by flushing away waste products. He realized that to reconstitute the dynamic nature of genes going up and down, he would need to have a mechanism for degrading what you make. Other synthetic biologists have also begun installing their DNA programs outside of living things, such as on sheets of paper, in the hopes of creating new kinds of diagnostic tests.

Creating artificial cells and tissue have been a hot topic lately, as scientists continue to work toward creating complex artificial tissue, specifically of the heart, liver, and lungs. Recently scientists have even begun producing artificial blood vessels, in an attempt to tackle one of the major issues involved in artificial tissue engineering.

As for Bar-Ziv, he hopes his chip could eventually lead to breakthrough applications in programmable biological sensors, diagnostics, environmental sensing, and possible drug screening. Scientists say the chips could also be used to test new genetic constructs before they're put into actual cells, like bacteria.

According to Bar-Ziv, the next step is to create more complex patterns and larger networks. It's his hope that they can eventually be able to control hundreds of different genes in thousands of artificial cells at once, allowing them to communicate with and influence one another, much like a living organism. However, Bar-Ziv concedes that day is still a ways in the future. "Going from one transistor to billions didn't happen in a day," he admits.

Refresh your medical device industry knowledge at MD&M West, in Anaheim, CA, February 10-12, 2015.

Kristopher Sturgis is a contributor to Qmed and MPMN.

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