Making A Light-harvesting Antenna From Scratch

Sometimes when people talk about solar energy, they tacitly assume that we're stuck with some version of the silicon solar cell and its technical and cost limitations. Not so. The invention of the solar cell, in 1941, was inspired by a newfound understanding of semiconductors, materials that can use light energy to create mobile electrons -- and ultimately an electrical current.

Silicon solar cells have almost nothing to do with the biological photosystems in tree leaves and pond scum that use light energy to push electrons across a membrane -- and ultimately create sugars and other organic molecules.

At the time, nobody understood these complex assemblages of proteins and pigments well enough to exploit their secrets for the design of solar cells.

But things have changed.

At Washington University in St. Louis's Photosynthetic Antenna Research Center (PARC) scientists are exploring native biological photosystems, building hybrids that combine natural and synthetic parts, and building fully synthetic analogs of natural systems.

One team has just succeeded in making a crucial photosystem component -- a light-harvesting antenna -- from scratch. The new antenna is modeled on the chlorosome found in green bacteria.

Chlorosomes are giant assemblies of pigment molecules. Perhaps Nature's most spectacular light-harvesting antennae, they allow green bacteria to photosynthesize even in the dim light in ocean deeps.