By Julián Villarreal, The University of Texas at Austin, Korgel Research Group and MRS Student Chapter
Overview – Nanobionics and photosynthesis
The chloroplast photosynthetic machinery is the energetic cornerstone for nearly every ecosystem on the planet, providing the ultimate source of all sustenance as well as the chemical energy in carbon-based fuels. Recent work by the Strano group at MIT, published last month in Nature Materials, provides a glimpse into a previously unexplored territory of plant nanobionics that promises to enhance the solar-energy conversion efficiency of this all-important process. Giraldo et al. have shown single-walled carbon nanotubes (SWNTs) localize themselves within the lipid bilayer envelope of chloroplasts extracted from plants by irreversibly passing through the lipid envelope, and that these SWNTs yield as much as a threefold enhancement in photosynthetic activity.
More in depth – Enhancing photocatalytic activity in chloroplasts with carbon nanotubes
The researchers were able to show by means of confocal Raman spectroscopy 3D mapping and near-infrared fluorescence imaging that SWNTs coated with either single-stranded DNA [ss(AT)15] or chitosan were able to embed themselves in the extracted chloropasts. In addition, it was shown that the ss(AT)15-SWNTs could be delivered to chloroplasts in vivo. Enhanced photocatalytic activity of the extracted chloroplasts assembled with SWNT-nanoceria complexes was shown by higher rates of reduction of dichlorophenolindophenol (DCPIP), an electron-acceptor dye. Photosynthesis of these chloroplasts was also characterized by chlorophyll fluorescence. The researchers were able to show via these tests that the maximum electron transport rates could be increased with SWNTs in both extracted chloroplasts and in vivo.
These results not only offer the prospect of increasing the solar energy captured by chloroplasts via the mechanism of SWNT delivery, but might also be a harbinger of other nanoengineered organelles and as-yet-unimagined nanotechnological breakthroughs in the interfacing of nanomaterials and biological structures.
The discussed paper from the Strano group
J. P. Giraldo et al., “Plant nanobionics approach to augment photosynthesis and biochemical sensing,” Nat. Mater. 13, 400-408 (2014)