Do you remember the shining flowers and plants on the planet Pandora in the "Avatar" movie? There is also the "tree of hope" seeds flying all over the sky like luminous jellyfish, dotted with the fantasy forest. Now the fairy tale world imagined by visionaries is being realized by scientists.
Above: The glowing plants in "Avatar"
Let us imagine: If plants rely on their own metabolic energy, they can turn themselves into lights that illuminate the night and illuminate our desks. Dispel the darkness on the road without plugging in a power source. What kind of fairy tale world will our living environment become?
However, in fact, researchers from MIT began to gradually turn these fantasies into reality as early as 2017. At that time, they embedded special nanoparticles into the leaves of watercress , thereby inducing watercress to emit weak light for four consecutive hours.
Above: Use nano-luminescent plants to illuminate a book. The picture shows two 3.5-week-old watercress plants.
These watercress are the first luminous plants that can be used for lighting. In order to create luminous watercress, MIT researchers focused on luciferase , which happens to be the substance that makes firefly glow. Luciferase acts on a molecule called luciferin that can emit light. Another molecule called Coenzyme A helps by removing reaction byproducts that can inhibit luciferase activity.
Above: Firefly
Researchers packaged each of these three components into different types of nanoparticle vectors. Then suspend the nanoparticles in the solution,The plant is immersed in the solution, and then exposed to high pressure, so that the particles enter the plant body through the stomata on the leaf surface.
particles that release luciferin and coenzyme A are designed to accumulate in the extracellular space (the inner layer of the leaf) of the mesophyll of , while the smaller particles carrying luciferase enter the cells that make up the mesophyll. It's just that the light produced by a 10 cm watercress seedling is very weak, only one-thousandth of the amount of light required for reading.
Now, in subsequent experiments, the same research team once again used the method of embedding special nanoparticles in plant leaves to create a luminous plant that can store LED light. This time, after only 10 seconds of charging, these plants can continue to glow for a few minutes, and they can be used repeatedly. The important thing is that the light produced by these plants is 10 times brighter than the first generation of luminous plants in 2017. The latest results have been published in the journal Science on September 8, 2021.
This is an example of plant nanobionics by embedding different types of nanoparticles in plants to give plants new characteristics. In the new research, in order to find a way to extend the light time and make it brighter, the researchers came up with something like capacitor . Know that in electronic devices, capacitors can store electrical energy and release electrical energy when needed. Corresponding to luminous plants, they think it may be possible to create a "light capacitor" that stores light in the form of photons , and then gradually releases it over time.
After careful consideration, the researchers decided to use a material called phosphor to make a "photocapacitor". These materials can absorb visible light or ultraviolet light, and then slowly release in the form of phosphorescence . In the experiment,They used strontium aluminate (a type of phosphor) to form nanoparticles, and before embedding the nanoparticles into plants, they were coated with silica to protect the plants from the compounds.
Above: Nano particles infiltrate the plant
These particles with a diameter of several hundred nanometers penetrate into the plant through the stomata located on the surface of the leaf and accumulate in the sponge layer called the mesophyll to form a thin film . This kind of film allows the mesophyll of living plants to absorb photons from sunlight or LEDs without harming the plants or sacrificing lighting characteristics.
Above: The green part is nanoparticles, which gather on the surface of the spongy mesophyll of plant leaves.
Researchers show that after receiving blue LED for 10 seconds, these nano-particle-added plants can glow for about an hour, and can maintain the highlight for the first five minutes, and then gradually weaken, and can be continuously charged for at least two week.
In addition, the researchers said that this method of adding "photocapacitors" can also be used in many different plants, such as basil, watercress and tobacco. For example, they also make the leaves of a plant called Thai elephant ears shine. This plant is more than 30 cm wide and can be used as an outdoor light source. At the same time, there is no need to worry that nanoparticles will interfere with the normal physiological activities of plants.
The experiment found that within 10 days, plants can always photosynthesize normally and evaporate water through stomata. After the experiment, the researchers were still able to extract about 60% of the phosphor from the plant and reuse it in another plant. Moreover, researchers are now working on combining phosphorescent capacitor particles with the luciferase nanoparticles they used in their 2017 study to produce plants that can produce brighter light over a longer period of time.
It can be seen from this,In the future, these plants will become an important tool for human lighting, and become an integral part of the infrastructure in human society, and even replace the current public lighting in cities. Maybe the trees on both sides of the road will be the street lights for us in the future. No wonder there is such a sentence: The one who kills you will never be your colleague.
Extended reading
Light-emitting plants are not only made by humans, but there are actually some creatures that can emit light in nature. For example, small fluorescent mushrooms are extremely rare fungi. They are also called ant street lamps and fluorescent mushrooms. They emit a faint green light similar to a ghost fire in the dark.
There is also a luminous tree, the queen of night. The plant has a large amount of phosphorus, which makes it glow at night. For example, the stamens of the Queen of the Night are rich in phosphorus, which emits fluorescence like fireflies. Among them, noctilucent trees are mainly distributed in the virgin forests of North America and Wugong Mountains in Jiangxi, my country.
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