Researchers use engineered viruses to provide quantum-based enhancement of energy transport

October 15, 2015 by David L. Chandler
Rendering of a virus used in the MIT experiments. The light-collecting centers, called chromophores, are in red, and chromophores that just absorbed a photon of light are glowing white. After the virus is modified to adjust the spacing between the chromophores, energy can jump from one set of chromophores to the next faster and more efficiently. Credit: Courtesy of the researchers and Lauren Alexa Kaye

Nature has had billions of years to perfect photosynthesis, which directly or indirectly supports virtually all life on Earth. In that time, the process has achieved almost 100 percent efficiency in transporting the energy of sunlight from receptors to reaction centers where it can be harnessed—a performance vastly better than even the best solar cells.

One way plants achieve this efficiency is by making use of the exotic effects of quantum mechanics—effects sometimes known as "quantum weirdness." These effects, which include the ability of a particle to exist in more than one place at a time, have now been used by engineers at MIT to achieve a significant efficiency boost in a light-harvesting system.

Surprisingly, the MIT researchers achieved this new approach to solar energy not with high-tech materials or microchips—but by using genetically engineered viruses.

This achievement in coupling quantum research and genetic manipulation, described this week in the journal Nature Materials, was the work of MIT professors Angela Belcher, an expert on engineering viruses to carry out energy-related tasks, and Seth Lloyd, an expert on quantum theory and its potential applications; research associate Heechul Park; and 14 collaborators at MIT and in Italy.

Lloyd, a professor of mechanical engineering, explains that in photosynthesis, a photon hits a receptor called a chromophore, which in turn produces an exciton—a quantum particle of energy. This exciton jumps from one chromophore to another until it reaches a reaction center, where that energy is harnessed to build the molecules that support life.

But the hopping pathway is random and inefficient unless it takes advantage of that allow it, in effect, to take multiple pathways at once and select the best ones, behaving more like a wave than a particle.

This efficient movement of excitons has one key requirement: The chromophores have to be arranged just right, with exactly the right amount of space between them. This, Lloyd explains, is known as the "Quantum Goldilocks Effect."

The video will load shortly
See how researchers genetically engineer viruses to more efficiently transport energy. Credit: Melanie Gonick/MIT

That's where the virus comes in. By engineering a virus that Belcher has worked with for years, the team was able to get it to bond with multiple synthetic chromophores—or, in this case, organic dyes. The researchers were then able to produce many varieties of the virus, with slightly different spacings between those synthetic chromophores, and select the ones that performed best.

In the end, they were able to more than double excitons' speed, increasing the distance they traveled before dissipating—a significant improvement in the efficiency of the process.

The project started from a chance meeting at a conference in Italy. Lloyd and Belcher, a professor of biological engineering, were reporting on different projects they had worked on, and began discussing the possibility of a project encompassing their very different expertise. Lloyd, whose work is mostly theoretical, pointed out that the viruses Belcher works with have the right length scales to potentially support quantum effects.

In 2008, Lloyd had published a paper demonstrating that photosynthetic organisms transmit light energy efficiently because of these quantum effects. When he saw Belcher's report on her work with engineered viruses, he wondered if that might provide a way to artificially induce a similar effect, in an effort to approach nature's efficiency.

"I had been talking about potential systems you could use to demonstrate this effect, and Angela said, 'We're already making those,'" Lloyd recalls. Eventually, after much analysis, "We came up with design principles to redesign how the virus is capturing light, and get it to this quantum regime."

Within two weeks, Belcher's team had created their first test version of the engineered virus. Many months of work then went into perfecting the receptors and the spacings.

Once the team engineered the viruses, they were able to use laser spectroscopy and dynamical modeling to watch the light-harvesting process in action, and to demonstrate that the new viruses were indeed making use of quantum coherence to enhance the transport of excitons.

"It was really fun," Belcher says. "A group of us who spoke different [scientific] languages worked closely together, to both make this class of organisms, and analyze the data. That's why I'm so excited by this."

While this initial result is essentially a proof of concept rather than a practical system, it points the way toward an approach that could lead to inexpensive and efficient or light-driven catalysis, the team says. So far, the engineered viruses collect and transport energy from incoming light, but do not yet harness it to produce power (as in solar cells) or molecules (as in photosynthesis). But this could be done by adding a reaction center, where such processing takes place, to the end of the virus where the excitons end up.

"This is exciting and high-quality research," says Alán Aspuru-Guzik, a professor of chemistry and chemical biology at Harvard University who was not involved in this work. The research, he says, "combines the work of a leader in theory (Lloyd) and a leader in experiment (Belcher) in a truly multidisciplinary and exciting combination that spans biology to physics to potentially, future technology."

"Access to controllable excitonic systems is a goal shared by many researchers in the field," Aspuru-Guzik adds. "This work provides fundamental understanding that can allow for the development of devices with an increased control of flow."

Explore further: How molecular vibrations make photosynthesis efficient

More information: Heechul Park et al. Enhanced energy transport in genetically engineered excitonic networks, Nature Materials (2015). DOI: 10.1038/nmat4448

Related Stories

How molecular vibrations make photosynthesis efficient

July 10, 2015

Plants and bacteria make use of sunlight with remarkably high efficiency: nine out of ten absorbed light particles are being put to use in an ordinary bacterium. For years, it has been a pressing question of modern research ...

Quantum entanglement in photosynthesis and evolution

July 21, 2010

Recently, academic debate has been swirling around the existence of unusual quantum mechanical effects in the most ubiquitous of phenomena, including photosynthesis, the process by which organisms convert light into chemical ...

What is quantum in quantum thermodynamics?

October 12, 2015

(Phys.org)—A lot of attention has been given to the differences between the quantum and classical worlds. For example, quantum entanglement, superposition, and teleportation are purely quantum phenomena with no classical ...

The topolariton, a new half-matter, half-light particle

October 7, 2015

A new type of "quasiparticle" theorized by Caltech's Gil Refael, a professor of theoretical physics and condensed matter theory, could help improve the efficiency of a wide range of photonic devices—technologies, such as ...

Recommended for you

Uncovering the secrets of water and ice as materials

December 7, 2016

Water is vital to life on Earth and its importance simply can't be overstated—it's also deeply rooted within our conscience that there's something extremely special about it. Yet, from a scientific point of view, much remains ...

Blocks of ice demonstrate levitated and directed motion

December 7, 2016

Resembling the Leidenfrost effect seen in rapidly boiling water droplets, a disk of ice becomes highly mobile due to a levitating layer of water between it and the smooth surface on which it rests and melts. The otherwise ...

The case for co-decaying dark matter

December 5, 2016

(Phys.org)—There isn't as much dark matter around today as there used to be. According to one of the most popular models of dark matter, the universe contained much more dark matter early on when the temperature was hotter. ...

2 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

betterexists
not rated yet Oct 16, 2015
From Viruses to Bacteria, Here we Come?
JVK
1 / 5 (2) Oct 19, 2015
Excerpt: "Once the team engineered the viruses, they were able to use laser spectroscopy and dynamical modeling to watch the light-harvesting process in action, and to demonstrate that the new viruses were indeed making use of quantum coherence to enhance the transport of excitons."

Does this suggest they engineered viruses that could more efficiently steal the energy of life?

What would prevent them from creating a virus and inserting it into a yeast cell and spreading the yeast, like anthrax (or more efficiently), but targeting human populations that were less likely to have ecologically adapted organized genomes that protected them from the damage to brain cells caused by viral microRNAs?

Thanks to Greg Bear for alerting us to that possibility in his science fiction novel: "Quantico"

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.