Learning tricks from bacteria to create better solar

From mimicking bird wings in aerofoil design to modifying burdock seed pods into Velcro, many engineering innovations take inspiration from nature.

A new award from the U.S. Department of Energy Early Career Research Program will help UChicago Pritzker School of Molecular Engineering (PME) Asst. Prof. Allison Squires learn new tricks from nature that could be used to improve artificial light harvesting technologies such as solar cells. Squires was one of 91 recipients of the Early Career Award announced Tuesday.

“I'm absolutely thrilled and honored to be selected for the DOE Early Career Award,” said Squires, a Neubauer Family Assistant Professor of Molecular Engineering at PME. “DOE program officers are great about connecting the scientists in their program to nucleate new collaborations, so I'm looking forward to meeting up with other folks in my program who are tackling similar questions from different angles.”

Established in 2010, the DOE Office of Science Early Career Research Program provides an annual funding opportunity for “outstanding scientists early in their careers” in universities and DOE national laboratories.

“Investing in cutting edge research and science is a cornerstone of DOE's mission and essential to maintaining America’s role as a global innovation leader,” U.S. Secretary of Energy Jennifer M. Granholm said in the award announcement.

Rather than explore photosynthesis in plants, Squires’ team will research how cyanobacteria, commonly called blue-green algae, efficiently turn light into energy in a wide range of environments, seasons, and weather events.

“Wouldn't it be great if we had solar cells that worked as well as photosynthesis?” Squires said. “Nature has evolved extraordinarily efficient, elegant, and adaptable mechanisms for harvesting energy from sunlight.”

While plants use chlorophyll to capture sunlight, cyanobacteria additionally use a unique antenna complex called a phycobilisome, which captures a broader range of wavelengths.

“If chlorophyll is arranged in a membrane like patches of grass in a field, then a phycobilisome might be a sculpted tree or bush in the middle of that field,” Squires said. “There are some similarities, but it’s a totally different structure and means of achieving a similar end. Cyanobacteria use both methods to harvest sunlight.”

All photosynthetic organisms must be able to control how much solar energy they harvest under changing environmental conditions, and cyanobacteria, which live in diverse environments from the ocean to the tundra, have evolved particularly elegant and versatile ways to tune their photosynthetic production. They have evolved specialized proteins that can bind to and quench the phycobilisome when the sun gets too bright. There is also some evidence that phycobilisomes are able to rearrange their size and shape based on environmental conditions.

“What makes these mechanisms fascinating is that they use very simple, repeated components —almost like Legos — yet it seems that they can control the organizations of those building blocks into lots of different arrangements, that might alter the function of phycobilisome,” Squires said. “We're trying to figure out what's changing, what the triggers are, and how to control it.”

Squires and her team, including PhD candidate Ayesha Ejaz, who generated the preliminary data for this proposal and helped build the main instrument the team will use in its research, will receive $875,000 over five years. The team will collaborate with Michigan State University bioengineer Cheryl Kerfeld and Prof. Gregory A. Voth from UChicago Chemistry.