In brief: Plastic that can breaks itself down when no longer needed sounds like something from sci-fi, but Chinese scientists have moved the idea closer to reality. Their prototype embeds dormant bacteria inside a polymer, creating a material that can activate on command and degrade without leaving behind microplastic fragments.

Scientists at the Shenzhen Institutes of Advanced Technology have developed a "living plastic" with a built-in kill switch. The material contains spores from engineered Bacillus subtilis, a common soil bacterium, that remain inactive during normal use.

When exposed to the trigger, the spores wake up and produce enzymes that digest the plastic from within.

The work, published in ACS Applied Polymer Materials, builds on earlier living-plastic experiments that mostly relied on a single enzyme.

The team used two separate bacterial strains that cooperate. One produces Candida antarctica lipase, which randomly cuts long polymer chains into shorter pieces. The other produces Burkholderia cepacia lipase, which chews through those fragments from the ends until they are reduced to small molecules.

Plastic's long, tightly packed molecular chains make the material durable but difficult for enzymes to attack. By creating fresh break points, the first enzyme gives the second one more places to work.

The researchers mixed the dormant spores into polycaprolactone, a polyester used in 3D-printing filaments and some dissolvable surgical sutures. The resulting film reportedly had mechanical properties similar to ordinary polycaprolactone, suggesting the embedded microbes did not ruin the material's usefulness.

When the plastic was placed in a nutrient broth heated to 122 degrees Fahrenheit, the spores activated and the film fully degraded within six days.

The researchers said the process did not create microplastic particles, which could make this more appealing than conventional biodegradable plastics, which often fragment before they fully break down.

The team also built a prototype wearable electrode (below) using the living plastic. It detected muscle signals from the arm, then degraded within about two weeks after the same activation treatment. The copper circuitry remained behind, meaning similar materials could eventually help separate recoverable electronics from disposable polymer layers.

There are some caveats. The demonstration used a relatively easy-to-degrade polymer, not the polyethylene, polypropylene, or PET found in much of the world's plastic waste. The trigger also required warm nutrient broth, which is fine in a lab but not exactly practical for ocean waste or consumer packaging.