The global energy consumption attributed to direct and indirect lighting accounts for nearly 20 percent of demand and over 2 Gt of CO2 emissions per year. The rapid growth of cities and urbanizing regions around the world is changing the ways in which urban infrastructure is conceived, powered, delivered and maintained. Typical municipal lighting requires complex electrical grids and infrastructure, keeping many developing nations around the world literally in the dark. Researchers at MIT think they may have a solution to this ongoing problem: nanobionic light-emitting plants. Two mature watercress are used as nanobionic light-emitting plants to illuminate John Milton’s Paradise Lost. Courtesy of MIT. “The vision is to make a plant that will function as a desk lamp — a lamp that you don’t have to plug in,” said Michael Strano, the Carbon P. Dubbs Professor of Chemical Engineering at MIT. “The light is ultimately powered by the energy metabolism of the plant itself.” Plant nanobionics is a new research field pioneered by the Strano research group at MIT. It aims at addressing the challenges of resource extraction for lighting technologies, urban lighting implementation, power, maintenance and disposal of batteries, bulbs, semiconductor circuit chips and other streams of e-waste and hardware from traditional bulb-based grid lighting. “Plant-based lighting would be a tremendous and profoundly impactful global energy revolution,” said MIT postdoc Seon-Yeong Kwak. “We envision a new platform and model for ambient lighting that is formed, grown, deployed and composted in a natural infrastructure that is safe, renewable and compostable at end of life.” To create these illuminated plants, the Strano research group is using luciferase — the enzyme that makes fireflies glow. The enzyme reacts with a molecule called luciferin, causing it to emit light in the presence of adenosine triphosphate (ATP). Adding another molecule to the mixture — coenzyme A — extends the duration of the light emission. Kwak told Photonics Media that they have modified watercress, arugula, spinach and kale by submerging them in pressurized chambers containing a nanoparticle suspension. “The light generated by one 10-cm watercress seedling is currently about one-thousandth of the amount needed to read by. We yielded plants that could glow for nearly four hours,” said Kwak. “Our next step is optimization. There are two aspects to the light-emitting plant that has to be optimized: the brightness and the duration of the light. We’ve shown that both can be optimized to extraordinarily high levels.” Nanobionic light-emitting plants could soon be used for low-intensity indoor architectural lighting and could one day transform trees into self-powered streetlights.