Most plastic packaging gets used for minutes and then sits in the environment for centuries. A team of researchers thinks it has a fix: plastic that comes with its own built-in disposal system, engineered right into the material itself.
In a study published in ACS Applied Polymer Materials, scientists describe a “living plastic” embedded with dormant spores of the bacterium Bacillus subtilis. Left alone, the spores sit inertly inside the plastic, and the material behaves like ordinary polycaprolactone, a polymer commonly used in 3D printing and surgical sutures.
The trick is what happens when it’s time to get rid of it. The bacteria were engineered to produce two enzymes that work as a team: one slices the plastic’s long polymer chains into smaller fragments at random points, and the second chews those fragments down from the ends into simple monomer building blocks. To switch the process on, researchers soak the material in a nutrient broth warmed to about 122°F (50°C), which wakes the spores up and sets the enzymes loose.
The results were striking: within six days, the plastic was completely broken down, and because the two enzymes worked in sequence rather than just shredding the material, it never fragmented into the tiny microplastic particles that plague other “biodegradable” plastics.
To show it could work outside the lab, the team built a wearable plastic electrode from the material. It performed normally in use, then fully disappeared within two weeks of activation.
As corresponding author Zhuojun Dai put it, the goal was to ask whether degradation could be “built directly into the material’s life cycle” rather than left to chance. Researchers are now working on ways to activate the spores in water, where much of the world’s plastic pollution ends up, and believe the same approach could eventually be adapted to other everyday plastics.
