Can plants take on new roles with tiny carbon materials?

Michael Strano thinks our use of plants has been too limited.

Sure, we've manipulated them to produce more food, sprout prettier flowers and grow faster. But Strano, a professor at the Massachusetts Institute of Technology in Cambridge, Mass., wants to give them totally new functions as sensors, antennae and tiny power plants.

"For millennia, we've used plants for wood, fruit and burning — very low-tech functions," said Strano, a professor of chemical engineering. "It's time to ask whether they can form the basis for very sophisticated technologies."

Along with colleagues, including plant biologist Juan Pablo Giraldo, Strano has modified the function of a small flowering plant, Arabidopsis thaliana, to transform it into a living sensor for the nitric oxide that leads to air pollution. The two say they could imagine vast crop fields studded with the occasional plant sensor, which could, if exposed to nitric oxide, light up enough to be detected by a camera and report on air quality.

In a paper published recently in the journal Nature Materials, they also showed that they could enhance photosynthesis, the first step toward using plants to make more biofuels. Plants have an incredible ability to make energy from nothing more than sunlight and air — so why not extend that ability to create energy in new materials that can repair themselves like plants and not only don't pollute but actually absorb greenhouse gases like carbon dioxide in the process, Giraldo said.

This may sound far-fetched, but James J. Collins, a biomedical engineer at Boston University, said he was impressed with the team's ideas and how much they've accomplished so far. No one has previously linked plant biology with synthetic biology, which designs and constructs biological devices for useful purposes, said Collins, a founder of that field.

"I thought it was fascinating," Collins said of the new paper. "This opens up more rapid ways you can modify organisms together."

Strano and his team inserted incredibly tiny particles directly into the chloroplasts — the part of the cell where photosynthesis takes place — to lower the concentration of damaging oxygen radicals. This allowed those chloroplasts to work and produce energy in a dish.

The same tiny particles delivered through the leaves appeared to enable the chloroplasts to capture green light, the kind green plants normally don't absorb. This allowed the modified plant to capture 30% more light energy than normal plants.

In another experiment, the team used nanoparticles that can detect nitric oxide to turn the plant into a pollution sensor.

There's still a long way to go before this field, which Strano calls plant nanobionics, will be ready for the real world. But the promise is real, Strano said.

Plants have no moving parts, they repair themselves, and they need little more than sunlight to begin the production process.

For instance, Strano envisions trees that work as cellphone towers, instead of building cellphone towers that look like trees.

"We haven't thought about merging this inorganic world with the biology of the tree," he said, but "that's completely within the realm of possibility."

In a different lab at MIT, biological engineer Timothy Lu and his colleagues are working to grow materials like electrical switches, solar materials and living glues.

"What biology is really good at is you plant something small and it grows. Essentially what we're doing is designing cells that can grow useful materials for us," Lu said.

In a paper published Sunday also in Nature Materials, Lu and his team tinkered with the genes of a strain of harmless bacteria, turning the microbes into an electrical switch.

Don't expect one of these in a nearby hardware store anytime soon, but Lu says the first products made by these bacteria factories could be available in the next few years.

"It's definitely something we can do now in the lab, it's a question of what's the best way to bring that to the world."