Nano, bio converge to provide key nanotech link

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Aug. 6, 2004 – Biology is the nanotechnology that works. Or so says Tom Knight, a senior researcher at the Artificial Intelligence Laboratory at Massachusetts Institute of Technology. That’s a startling statement, especially when it’s coming from a computer scientist.

It’s no surprise, though, if you consider that Knight is part of MIT’s Synthetic Biology Working Group. Its aim is to develop a library of interoperable genetic parts with specific functions. These genes, proteins and cells could be snapped together like Tinkertoys to build complex systems that don’t already exist in nature.

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Gene jockeys have a head start on nanoscientists. PCR (polymerase chain reaction), the method of mass producing DNA fragments essential to biotechnology, was invented in 1985, and the Human Genome Project kicked off five years later. By the time carbon nanotubes were discovered in 1991, biotech was already big business.

Finally though, biologists are poised to make genetic engineering worthy of its name. Synthetic biology is about rewiring networks of genes, “genetic circuits,” to create entirely new biological devices.

Think about the microbial “factory” developed at University of California, Berkeley. It produces an anti-malarial drug, potentially cutting the cost of pills from dollars to dimes and saving millions of lives every year.

There is also the DNA-based BioBricks in Knight’s laboratory that could form the basis for myriad nanoscale devices, including cellular computers hardwired with genetic programs.

Continuing the electronics metaphor, UC Berkeley computer scientist Adam Arkin is developing BioSPICE, a CAD tool for genetic circuits analogous to the industry-standard SPICE (Simulation Program Integration Circuitry Evaluation) software for integrated circuit design.

“Most genetic engineering is done by hook or by crook,” Arkin says. “It takes a lot of trial and error to build simple things into cells, like the ability to produce a lot of a functional protein. Now though, we want to actually program cells as if they’re computers so they can do much more complicated tasks.”

Of course, nano and bio have been on convergent paths for quite some time. According to the National Science Foundation, the annual nanobiotechnology market will jump to $36 billion by 2006. From biosensors and disease detectors to novel drug delivery systems and tissue engineering techniques, biological applications of nanotechnology already have begun to transform medicine.

Still, the better we get at hijacking, and even designing, biological systems, the broader the impact of the nano-bio convergence.

It’s not going to happen tomorrow, though. “It’s not so easy to fuse biomaterials with inorganic matter in a functional nanodevice that’s robust and lasts a long time,” said nanotechnology pioneer James Gimzewski, a chemistry professor at University of California, Los Angeles.

“It’s just not realistic to expect nanotechnology to be entirely based on biology as some people believe. But in the long term, interesting things will happen where they converge.”

The nano-bio baby has indeed taken its first steps. Consider diatoms, single-celled algae that boast beautiful glass shells. Researchers at UC, San Diego, UC Berkeley and several other laboratories are reverse-engineering diatoms in the hopes of harnessing their ability to build precise nanostructures.

As is, the shells could be used as tiny glass test tubes for chemical reactions or gears in micromachines. Some scientists believe that with some non-trivial genetic engineering, the algae could be coaxed into cranking out shells shaped to order.

At MIT, materials scientist Angela Belcher engineers and evolves biological organisms to assemble useful nanodevices. For example, earlier in her career Belcher altered the proteins in bacteriophages so that the viruses assembled themselves into the building blocks of liquid crystal displays.

More recently, she produced a virus that coats itself with semiconducting material and forms a bridge between two electrodes. That nanowire virus is just a precursor to a microbe she’s developing that self-assembles into a transistor.

While Belcher enlists bacteria to build nanostructures, other researchers are employing strands of DNA as workhorses for the construction of nanostructures. Individual DNA strands can be “programmed” with complementary bases that bind together to form specific shapes.

In the last few years New York University chemist Nadrian Seeman has programmed DNA strands that link themselves together into octahedrons, scaffolds, and even a nanomotor. His most startling breakthrough was announced in May, though.

Seeman reported that he had built a DNA “robot,” just 10 nanometers long that shuffled along a tiny track. The next step, Seeman said, was to enable the biped to lug around a metal atom. If these early results are any indication, Knight may need to expand his motto: Biology may actually be the nanotechnology that makes nanotechnology work.

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