Imagine that instead of lighting a lamp when it's dark, you could read in the light of a luminous plant on your desk.
The US engineers at MIT, Massachusetts Institute of Technology, have taken a critical first step in making this vision a reality. By incorporating specialized nanoparticles into the leaves of a cress plant, engineers have induced the plants to emit dim light for almost four hours. They believe that, with further optimization, such plants will one day be bright enough to light up a work space.
"The idea is to make a plant that will work like a desk lamp - a lamp that you do not have to connect to electricity. The light is permanently fueled by the energetic metabolism of the plant itself ", reports Michael Strano, the Carbon P. Dubbs, professor of Chemical Engineering at MIT and senior author of the study.
This technology could also be used to provide low-intensity indoor lighting or to transform trees into self-powered street lamps, the researchers say.
The post-doctoral study at MIT Seon-Yeong Kwak is the lead author of the study, which appears in the Nano Letters newspaper.
The nanobiotic plants, a new research area introduced by the laboratory of Dr. Strano, aims to give new characteristics to plants, incorporating them with different types of nanoparticles. The group's goal is to engineer plants to take control of many of the functions now performed by electrical devices. Researchers have previously designed plants capable of detecting explosives and communicating such information to a smartphone, as well as facilities that can monitor drought conditions.
Lighting, which represents about 20% of world energy consumption, seemed a logical next objective. "Plants can self-heal themselves, have their energy and are already adapted to the external environment," says Strano. "We think this is an idea whose time has come in. It's a perfect problem for plant nanobionics."
To create their incandescent plants, the MIT team turned to luciferase, the enzyme that gives the glowworms their glow. Luciferase acts on a molecule called luciferin, making it emit light. Another molecule called coenzyme A helps the process to remove a reaction by-product that can inhibit luciferase activity.
The MIT team has packaged each of these three components into a different type of nanoparticle carrier. The nanoparticles, which are all made up of materials that the US Food and Drug Administration classifies as "generally considered safe", help each component to reach the right part of the plant. Furthermore, they prevent components from reaching concentrations that could be toxic to plants.
The researchers used silica nanoparticles of about 10 nanometers in diameter to carry the luciferase, and they used slightly larger particles of PLGA polymers and chitosan to transport, respectively, the luciferin and the coenzyme A. To obtain the particles in the leaves of the plants , the researchers first suspended the particles in a solution. The plants were immersed in the solution and then exposed to high pressure, allowing the particles to enter the leaves through small pores called stomata.
The particles that release luciferin and coenzyme A have been designed to accumulate in the extracellular space of the mesophyll, an inner layer of the leaf, while the smaller particles carrying the luciferase enter the cells that form the mesophyll. PLGA particles gradually release luciferin, which then enters the plant's cells, where luciferase performs the chemical reaction that makes luciferin shine.
The early efforts of researchers at the beginning of the project produced plants that could shine for about 45 minutes, which then improved up to 3.5 hours. The light generated by a 10 cm watercress is currently about a thousandth of the amount needed to be read, but researchers believe they can increase the light emitted, as well as its duration, further optimizing the concentration and release of components.
La trasformazione delle piante
Gli sforzi precedenti per creare piante che emettano luce hanno fatto affidamento su piante geneticamente ingegnerizzate per esprimere il gene della luciferasi, ma questo è un processo laborioso che produce una luce estremamente debole. Tali studi sono stati condotti su piante di tabacco e Arabidopsis thaliana, che sono comunemente usati per studi di genetica vegetale. Tuttavia, il metodo sviluppato dal laboratorio di Strano potrebbe essere utilizzato su qualsiasi tipo di pianta. Finora, lo hanno dimostrato con rucola, cavolo e spinaci, oltre al crescione.
Per le versioni future di questa tecnologia, i ricercatori sperano di sviluppare un modo per dipingere o spruzzare le nanoparticelle sulle foglie delle piante, che potrebbero rendere possibile la trasformazione di alberi e altre piante di grandi dimensioni in fonti di luce.
"Il nostro obiettivo è quello di eseguire un trattamento quando la pianta è una piantina o una pianta matura, e farlo durare per tutta la vita della pianta", dice Strano. "Il nostro lavoro apre davvero seriamente la porta ai lampioni, che non sono altro che alberi trattati e all'illuminazione indiretta intorno alle case".
I ricercatori hanno anche dimostrato che possono spegnere la luce aggiungendo nanoparticelle che trasportano un inibitore della luciferasi. Ciò potrebbe consentire loro di creare piante che interrompano la loro emissione di luce in risposta a condizioni ambientali, come la luce solare, così riferiscono i ricercatori.
La ricerca è stata finanziata dal Dipartimento per l'energia degli Stati Uniti.
Fonti: MIT News
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