Self-assembling light-harvesting systems from synthetically modified tobacco mosaic virus coat proteins.

A new protein-based approach has been developed for the construction of light-harvesting systems through self-assembly. The building blocks were prepared by attaching fluorescent chromophores to cysteine residues introduced on tobacco mosaic virus coat protein monomers. When placed under the appropriate buffer conditions, these conjugates could be assembled into stacks of disks or into rods that reached hundreds of nanometers in length. Characterization of the system using fluorescence spectroscopy indicated that efficient energy transfer could be achieved from large numbers of donor chromophores to a single acceptor. Energy transfer is proposed to occur through direct donor-acceptor interactions, although degenerate donor-to-donor transfer events are also possible. Three-chromophore systems were also prepared to achieve broad spectrum light collection with over 90% overall efficiency. Through the combination of self-organizing biological structures and synthetic building blocks, a highly tunable new method has emerged for the construction of photovoltaic device components.