Nanotech on the Farm

The tropical root vegetable cassava is a staple crop for millions of people in sub-Saharan Africa. However, it’s tricky to handle. Once the root is removed from the ground and exposed to oxygen in the air, it spoils within one to three days, so farmers must get it to processing centers as soon as possible after harvest. If they don’t, the crop goes to waste.

A simple way to prolong cassava’s shelf life could help farmers avoid that waste and sell their crop beyond their local region. Now, scientists such as Paula Hammond ‘84, PhD ‘93, an MIT professor of chemical engineering, are working on an innovative approach that uses nanotechnology to help them do that. Their idea is to design a plastic storage bag lined with nano­particles that react with oxygen before it can affect the roots.

“That would enable farmers to harvest and store and process at times convenient to them,” says Hammond, who traveled to Kenya and Ghana last summer with an international group of scientists to meet with farmers and come up with new ways of improving agricultural efficiency.

It may seem odd to send Hammond, a chemical engineer who focuses on nanotechnology, to the aid of African farmers. But the Meridian Institute, which organized the trip with funding from the Bill and Melinda Gates Foundation, was looking for scientists who specialize in fields not traditionally involved in international development.

Meridian enlisted Jeffrey Carbeck, PhD ‘96, a chemical engineer and entrepreneur, to identify scientists who would fit in with the mission. “I was looking for people who had a deep technical background but had shown they could apply it in multiple areas,” says Carbeck, who knew Hammond from their graduate school days at MIT.

Carbeck thought that Hammond, an expert in designing polymers for drug delivery, sensors, and energy, was a great match. Hammond, in turn, was intrigued by the idea. “It sounded like such an important problem, and I had never been to Africa,” she says. “This was a chance to see it from a very unique perspective.”

For Hammond, the trip was enlightening. “These working families have very immediate problems and have neither the resources nor perhaps the voice to express them to groups of elite scientists,” she says. “That’s what this allowed them to do. These are really exciting problems outside the realm of what we might normally encounter in academia.”

She and other scientists in the group also came up with an idea to help give dairy farmers more time to get their milk to processing centers before it spoils: a container with a nanopatterned antimicrobial coating that would preserve milk longer than a plain plastic jug. And they’re working on a pregnancy test for cows, adapting existing nano­patterned paper sensors. (There is no simple, inexpensive bovine equivalent to the human pregnancy test.) The Meridian Institute is starting a foundation to help develop, test, and commercialize their ideas.