Some living things flash and fade in an instant. These scientists got that light to last.
Researchers have used bioluminescent algae to make 3D-printed lights, according to work published in Science Advances on May 6. The team said the technology could help build more sustainable light-emitting systems.
“This project was a moonshot idea,” said Wil Srubar, a study co-author and materials scientist at the University of Colorado Boulder, in a statement. “I was curious if we could create a world in which we don’t use electricity but rather use biology to produce light. This discovery really paves the way for engineering other living light materials and devices.”
Bioluminescence appears across many kingdoms of life, including animals, plants and fungi. As much as 90 percent of deep-sea creatures might be able to glow.
Srubar and his colleagues focused on the marine alga Pyrocystis lunula, a single-celled organism that briefly glimmers blue when disturbed by crashing ocean waves or passing boats. They wanted to find a way to sustain that illumination.
The team first tried to squish the algae to mimic those mechanical triggers. “They weren’t really responding to that,” said Giulia Brachi, a study co-author and bioengineer also at CU Boulder, to Chris Baraniuk at the Guardian.
The researchers then turned to chemistry. Previous studies had shown that P. lunula’s bioluminescence could be activated by exposure to certain chemical compounds.
The algae produce light using an enzyme called luciferase, which speeds up a chemical reaction between oxygen and a molecule called luciferin. That reaction produces a new molecule, and most of the energy released comes out as light.
The team placed some algae in a solution about as acidic as tomato juice and some in a solution about as basic as mild soap. In both cases the algae produced light. But the glow from the basic solution was diffuse and short-lived, which indicated cellular stress.
The acidic solution worked better. It helped the algae keep a concentrated glow for up to 25 minutes.
“It was a very exciting moment when we found the right chemical stimulant that allowed the light to stay on for a long time,” Brachi said in the statement. “This is the first time we have figured out how to sustain luminescence.”
The scientists then embedded the algae in a water-based gel and 3D-printed the material into several shapes, including a crescent moon, a grid and CU Boulder’s logo. The algae stayed alive in those structures for four weeks. At the end of the study period, the acid-treated samples still retained 75 percent of their glow when tested.
Srubar told the Guardian that this “living light” could be used for glowsticks or glimmering bracelets. With more work, he said, it could also provide battery-free lighting for autonomous robots in space or deep-sea conditions.
The researchers also said that if they find P. lunula responds to other chemicals, it could potentially be used to monitor toxins in water.
“Moving it from what works under controlled conditions in the lab to what works in the real world will be a challenge, but this is a really interesting first step,” said Chris Howe, a biochemist at the University of Cambridge who was not involved in the work, to the Guardian.
The study also points to another feature of the algae. Since they are photosynthetic, they remove some dissolved carbon dioxide to make their own food.
“We’re storing carbon while we’re producing light, whereas conventionally, we emit carbon to light up spaces,” Srubar said in the statement.
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