MIT researchers engineer light emitting plants
A professor of chemical engineering at MIT, Strano and his team have been working with four chemically interacting nanoparticles, embedding them into living plants (infusing them through the pores of their leaves) so they could then react throughout the plant’s tissues.
The nanoparticles included firefly luciferase conjugated silica (SNP-Luc), d-luciferin releasing poly(lactic-co-glycolic acid) (PLGA-LH2), coenzyme A functionalized chitosan (CS-CoA) and semiconductor nanocrystal phosphors.
Luciferase is the enzyme that gives fireflies their glow as it interacts with the molecule luciferin, while co-enzyme A helps the process along by removing a reaction by-product that would inhibit luciferase activity.
In a paper titled “A Nanobionic Light-Emitting Plant” published in Nano Letters, the researchers describe how they packaged these three components into nanoparticle carriers of different sizes and charges so they would reach different parts of the plant when solution-driven through the pores of a plant’s leaves. First, they had worked out the optimum nanoparticle sizes through the use of a nanofluidic mathematical model, then proceeded to infuse watercress through a pressurized bath infusion of nanoparticles in a solution.
What the researchers got were mature watercress plants that emitted over 1.44×1012 photons/s, equivalent to about 50% of 1μW commercial luminescent diodes. What’s more, they were able to modulate the dim glow in the “off” and “on” states by the chemical addition of dehydroluciferin and coenzyme A, respectively.
The project yielded plants that could glow up to 3.5 hours, though so dimly they would not qualify as useful light sources for reading or other activities. The researchers believe they can boost the light emitted, as well as the duration of light, by further optimizing the concentration and release rates of the different components. In the mix, the CdSe nanocrystals were proven to shift the chemiluminescent emission to 760nm enabling near-infrared (nIR) signalling.
“The vision is to make a plant that will function as a desk lamp — a lamp that you don’t have to plug in. The light is ultimately powered by the energy metabolism of the plant itself,” says Michael Strano, senior author of the study.
But getting there would mean engineering plants so they could produce themselves the necessary chemicals. Previous efforts to create light-emitting plants have relied on genetically engineering plants to express the gene for luciferase, but this is a laborious process that yields extremely dim light. Another alternative would be to spray the plants with a mist of the pre-engineered nanoparticles, if that could work to turn large trees into street luminaires.
“Our target is to perform one treatment when the plant is a seedling or a mature plant, and have it last for the lifetime of the plant,” Strano says. “Our work very seriously opens up the doorway to streetlamps that are nothing but treated trees, and to indirect lighting around homes.”