Plant nanobionics aims to embed non-native functions into plants by interfacing them with specifically designed nanoparticles. Michael S. Strano, Massachusetts Institute of Technology (MIT), Cambridge, USA, and colleagues have turned living spinach plants (Spinacia oleracea) into environmental sensors. For this purpose, they inserted a pair of near-infrared fluorescent nanosensors into the leaf tissue of the plants.
The sensors are a) single-walled carbon nanotubes (SWCNTs) conjugated to the peptide Bombolitin II to recognize nitroaromatics via infrared fluorescent emission, and b) polyvinyl-alcohol functionalized SWCNTs that act as an invariant reference signal. When nitroaromatics reach the leaf, it begins to fluoresce. Other chemicals or pollutants can also be detected using this method.
If there is a landmine or other explosive in the soil near the plant, the spinach will absorb small amounts of these nitrogen compounds together with the water. As the researchers report, it takes about ten minutes for these molecules to be transported from the roots to the leaf tissue. In the leaves, the nitroaromatics bind to the SWCTs, which activates the fluorescence. If the spinach plant is irradiated with a laser, the leaves emit light in the near-infrared range. An amplified light indicates that explosives are present in the ground.
According to the researchers, this development demonstrates the ability of living, wild-type plants to function as chemical monitors of groundwater.
- Nitroaromatic detection and infrared communication from wild-type plants using plant nanobionics,
Min Hao Wong, Juan P. Giraldo, Seon-Yeong Kwak, Volodymyr B. Koman, Rosalie Sinclair, Tedrick Thomas Salim Lew, Gili Bisker, Pingwei Liu, Michael S. Strano,
Nature Mater. 2016.