Fireflies inspire glow-in-the-dark plants that could replace desk lamps
Glow-in-the-dark plants have been developed by MIT engineers who embedded specialised nanoparticles into the leaves of a watercress plant.
The plants currently give off a dim light for nearly four hours and the team believes that with further optimisation such plants will one day be bright enough to illuminate a workspace.
“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,” said MIT Professor Michael Strano, senior author of the study.
This technology could also be used to provide low-intensity indoor lighting, or to transform trees into self-powered streetlights, the researchers say.
Plant nanobionics is a new research area that aims to give plants novel features by embedding them with different types of nanoparticles.
The group’s goal is to engineer plants to take over many of the functions now performed by electrical devices.
The researchers have previously designed plants that can detect explosives and communicate that information to a smartphone, as well as plants that can monitor drought conditions.
Lighting, which accounts for about 20 per cent of worldwide energy consumption, seemed like a logical next target.
“Plants can self-repair, they have their own energy and they are already adapted to the outdoor environment,” Strano said. “We think this is an idea whose time has come. It’s a perfect problem for plant nanobionics.”
To create their glowing plants, the MIT team turned to luciferase, the enzyme that gives fireflies their glow.
Luciferase acts on a molecule called luciferin, causing it to emit light. Another molecule called co-enzyme A helps the process along by removing a reaction byproduct that can inhibit luciferase activity.
The MIT team packaged each of these three components into a different type of nanoparticle carrier in order to help each component get to the right part of the plant.
They also prevent the components from reaching concentrations that could be toxic to the plants.
The researchers used silica nanoparticles about 10nm in diameter to carry luciferase and they used slightly larger particles of the polymers PLGA and chitosan to carry luciferin and coenzyme A, respectively.
To get the particles into plant leaves, the researchers first suspended the particles in a solution. Plants were immersed in the solution and then exposed to high pressure, allowing the particles to enter the leaves through tiny pores called stomata.
Particles releasing luciferin and coenzyme A were designed to accumulate in the extracellular space of the mesophyll, an inner layer of the leaf, while the smaller particles carrying luciferase enter the cells that make up the mesophyll.
The PLGA particles gradually release luciferin, which then enters the plant cells, where luciferase performs the chemical reaction that makes luciferin glow.
The researchers’ early efforts at the start of the project yielded plants that could glow for about 45 minutes, which they have since improved to 3.5 hours.
The light generated by one 10cm watercress seedling is currently about one-thousandth of the amount needed to read by, but the researchers believe they can boost the light emitted, as well as the duration of light, by further optimising the concentration and release rates of the components.
For future versions of this technology, the researchers hope to develop a way to paint or spray the nanoparticles onto plant leaves, which could make it possible to transform trees and other large plants into light sources.
Last year, Strano’s team developed nanobionic spinach that can detect explosives and send information wirelessly to a handheld device.
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