Light-harvesting antennas from laboratory constructs that are like ‘sun sponges’

As we know, plants are the best at harvesting energy from the sun but there are some scientists at Washington University in Saint Louis (Missouri, US) who claim they’ve developed a complex that’s better. From an Aug. 21, 2013 news item on Nanowerk,

In diagrams it looks like a confection of self-curling ribbon with bits of bling hung off the ribbon here and there. In fact it is a carefully designed ring of proteins with attached pigments that self-assembles into a structure that soaks up sunlight.

The scientists who made it call it a testbed, or platform for rapid prototyping of light-harvesting antennas–structures found in plants and photosynthesizing bacteria–that take the first step in converting sunlight into usable energy. The antennas consist of protein scaffolding that holds pigment molecules in ideal positions to capture and transfer the sun’s energy. The number and variety of the pigment molecules determines how much of the sun’s energy the antennas can grab and dump into an energy trap.

The Aug. 21, 2013 Washington University in Saint Louis news release by Diana Lutz, which originated the news item, provides more detail,

In the August 6, 2013 online edition of Chemical Science, a new publication of the Royal Society of Chemistry, the scientists describe two prototype antennas they’ve built on their testbed. One incorporated synthetic dyes called Oregon Green and Rhodamine Red and the other combined Oregon Green and a synthetic version of the bacterial pigment bacteriochlorophyll that absorbs light in the near-infrared region of the spectrum.

Both designs soak up more of the sun’s spectrum than native antennas in purple bacteria that provided the inspiration and some components for the testbed. The prototypes were also far easier to assemble than synthetic antennas made entirely from scratch. In this sense they offer the best of both worlds, combining human synthetic ingenuity with the repertoire of robust chemical machinery selected by evolution.

One day a two-part system (consisting of an antenna and a second unit called a reaction center) might serve as a miniature power outlet into which photochemical modules could be plugged. The sun’s energy could then be used directly to split water, generate electricity, or build molecular-scale devices.

The news release goes on to discuss the pigments used in the project and the complex’s self-assembly.

For those who want all the detail, here’s a link to and a citation for the published paper,

Integration of multiple chromophores with native photosynthetic antennas to enhance solar energy capture and delivery by Michelle A. Harris, Pamela S. Parkes-Loach, Joseph W. Springer, Jianbing Jiang, Elizabeth C. Martin, Pu Qian, Jieying Jiao, Dariusz M. Niedzwiedzki, Christine Kirmaier, John D. Olsen, David F. Bocian, Dewey Holten, C. Neil Hunter, Jonathan S. Lindsey and Paul A. Loach.  Chem. Sci., 2013, Advance Article DOI: 10.1039/C3SC51518D First published online 06 Aug 2013

I believe this is behind a paywall.

Leave a Reply

Your email address will not be published. Required fields are marked *