Can a living plant or tree become a future streetlight?
Plants are a living technology. They generate and store their own fuel from sunlight, acting as both a solar cell and a battery. They access the water they need from their environment and repair themselves. Plants are adaptive by nature and can thrive in diverse global environments—but can living plants in their wild and natural states with no genetic modifications be made to emit light? That was the big question asked by MIT chemical engineer Michael Strano and MIT professor of architecture Sheila Kennedy. The team’s response is quite illuminating: Yes. The goal of the project—the first collaboration at MIT between a chemical engineer and an architect—was to create new applications for useful, ambient lighting with living plants entirely off the electrical grid. This required the application of plant nanobionics (an innovation of Dr. Strano’s lab) and design expertise with the architecture of new societal infrastructures, a research focus of Professor Kennedy and her design team.
Functionalized nanoparticles delivered into a plant’s tissues tap the stored energy within its photosynthetic machinery, then use that energy to emit luminescence. “These nanoparticles are about the same size as the proteins from which the plants are built,” says Dr. Strano. “One of our aims is to learn how to control where they go within the plant in order to achieve the desired result.”
Plants are more sophisticated than any clean energy technology. Our work is a repositioning and a new prioritization of the plant world and a real epiphany that we need new forms of coexistence and partnerships between plants and people.”
A dim view of vision and risk-taking in research
“At this stage of my career,” says Dr. Strano, “I want to work on things that are risky. I enjoy the challenge and believe it’s the right thing for me to do.” While the concept of plants emitting light is not new, never before has anyone made it work. The difficulty in achieving the goal at the level of developing the underlying basic science and techniques, generating enough light to read by and designing ways to make this vision functional, practicable, and aesthetically compelling does not inspire traditional funding sources. Furthermore, a project that combines nanotechnology, plant biology, architecture, and urban design in such an unprecedented way is difficult for funders to grasp. Such a broad vision—even though it embraces grand challenges of carbon emissions and clean energy—places it beyond the scope of most institutional funders. The imagination and enthusiasm of the collaborators, however, make it perfectly aligned with the types of projects that the Bose Fellows program seeks to support.
Seeing the light
Dr. Strano and Professor Kennedy have already successfully demonstrated a prototype nanobionic plant which emits light, which the team says is “the brightest living thing ever created. ” The team’s next generation of light emitting plants was selected for exhibition at the Smithsonian Museum’s 2019 Design Triennial in New York City. There, the MIT team will invite museum visitors to experience the design of a future plant infrastructure and see how living, wild-growing plants that emit light are integrated in the daily life and residential architecture of an urban row house. Professor Kennedy states, “We don’t look critically enough at our existing electric infrastructure or our buildings. There is so much waste, toxicity, and non-renewable materials. We’re developing a new form of living illumination infrastructure with nature that is attractive for people to use, and completely independent of the electrical grid paradigm.”
A shining example
The pandemic did not darken the prospects of Dr. Strano and Professor Kennedy’s innovation. The Smithsonian exhibition became, in their words, “a practice run for how nanobiotic plants could be sustained in buildings over time.” The team created a scale model of a typical New York City residential walkup building in which light-emitting plants were grown and thrived. That experiment was successful but what happened next was even greater proof of their concept: the launching of a new research space by the National Science Foundation (NSF).
The NSF’s Emerging Frontiers in Research and Innovation (EFRI) program has begun soliciting proposals in a research area they have termed Engineered Living Systems (ELiS), prompted by research initiatives that learn from nature, such as the the team’s plant project. According to Dr. Strano, “The exposure that the Bose Fellows grant gave us was transformative. Our work is now in the scientific mainstream, inspiring other scientists to build on what we’ve done.” One of the team’s recent advances for plant-based lighting came from implanting biocompatible nanoparticles into the spongy mesophyll within the leaf. These serve to turn the mesophyll into a photonic capacitor that enables plants to both store and emit light while harvesting additional energy from the sun. This research was published in Science Advances in 2021.
Looking ahead, this work will lead to interdisciplinary advancements in science, architecture, and engineering, as cities require buildings that prioritize daylight and accommodate soil to sustain light-emitting plants. “As living infrastructure,” says Professor Kennedy, “plants provide important services and we can anticipate new and fruitful collaborations between plants and people.”