At BNL, big ideas come from thinking really small

BNL scientist Oleg Gang: The building blocks of the future, though tiny, hold enormous promise.

By GREGORY ZELLER // And you thought only children built with blocks.

Brookhaven National Laboratory scientists do, too – only their blocks are about one-billionth of a meter long and are held together by synthetic DNA strands. And it’s not actually the scientists doing the building, but the blocks themselves: Those strands, while much shorter than the twisted-ladder chains comprising, say, human cells, are encoded with instructions that enable the nanoparticles to “self-assemble.”

Mind blown yet? If not, consider this: While current technological limitations make handling nanoparticles time-consuming and cost-prohibitive, the potential of “nano-assembly” is virtually unlimited – as in, changing everything we know about the physicality of things and rewriting everything from energy production to construction. Yeah, nanoparticles are tiny. But this is huge.

A pair of studies published Monday in the London-based science journals Nature Materials and Nature Nanotechnology detail how BNL scientists are using DNA to combine nanoparticles and create new materials for all kinds of intriguing applications, including so-called “energy harvesting.” There’s enough scientific mumbo-jumbo at play to fill a textbook, but the upshot is this: Researchers can basically use lasers to train nanoparticles to stitch themselves into useful configurations.

Or, as scientist Kevin Yager of BNL’s Center for Functional Nanomaterials succinctly noted, to “design materials that build themselves.”

That’s a fairly simplistic summation of an amazingly complex process, but according to BNL physicist Oleg Gang, a Ukrainian immigrant and leader of the lab’s DNA-enabled nano-assembly efforts, it’s spot-on.

“We have these very small building blocks that we cannot handle with our hands or with a machine,” Gang said. “So we have to set up the right conditions and give those blocks the right instructions to do the job on their own.”

Using synthetic DNA as a sort of construction scaffolding – or the “glue” holding the tiny blocks together – has already resulted in a variety of nanoparticle assemblies. In one experiment, the BNL team gained precise enough control to place nanoparticles into predictable geometric configurations; potentially, this could allow researchers to orchestrate nanoparticles into materials that regulate energy flow, rotate light or deliver biomolecule payloads.

Other experiments have focused on combining nanoparticles that absorb light with nanoparticles that separate charges, thereby generating electricity.

“Some particles can manipulate light,” Gang noted. “Another can work as an antenna, another can work almost like a lens, magnifying an electromagnetic field. These are very simplistic analogies, but they are basically correct.”

It sounds simple enough, but to really get it, a bit of un-learning may be required. Hear the term “build” and you might visualize those colorful blocks of your youth, or some other process whereby physical objects are arranged to create a structure. What Gang’s team is doing is more organic – a “manufacturing process,” the physicist noted, “in some ways analogous to how plants are created, or any kind of biological process.”

“They’re not created by somebody putting one cell next to another next to another,” he said. “That’s how cars and computers and cell phones and everything else are created. But it’s not how biological organisms are created. This is a self-organization process in which we can create materials, even complex devices, in a way similar to how biology works.

“You put the components together in a cup,” he added. “They are smart enough to form an object. We don’t control the growth, it just happens on its own. You put components in a cup, and you get a cell phone out of the cup.”

Here Gang corrects himself – “The particles are not smart” – and stresses that human intervention is still required: Scientists must supply “very simplistic instructions” through the DNA strands to get the nanoparticles to play nice.

Another simplified analogy: a key and a lock that only work in combination. The idea is to pair the nanoparticle combinations in a way that produces the desired result, Gang said, and “there are a huge number of potential combinations.”

Hypothetically, this technology would be easily scalable; after all, “if you can do this with two particles,” according to Gang, “you can do it with many particles.” That means creating complex devices like that cell-phone-in-a-cup isn’t out of the question, and neither is using nano-assembly technology as an energy source.

Gang doesn’t imagine nano-assemblies being used to power something as large as a house or a car, but combine enough nanoparticles in an “energy harvesting” configuration and the notion of powering a tiny medical device implanted in the human body – or even something as big as that organically grown cell phone – isn’t unreasonable.

“There are a million different applications where you need smaller amounts of energy,” he noted.

The scientist bristles at the notion that this might all be just theoretical, noting BNL’s National Synchrotron Light Source has allowed his team to observe the manipulated nanoparticles at work and even see final structures. “We’re experimentalists,” Gang noted. “We only deal with reality.”

Predicting when the technology might be ready for commercialization, however, “is difficult.”

“It’s not going to happen tomorrow,” Gang said. “But I honestly think it’s feasible that 10 years from now, this is how it’s going to be.”