Researchers created a wearable plastic electrode out of their living plastic and found it performed as expected, degrading completely within two weeks.
Researchers have developed a new type of plastic that can self-destruct on command. These materials incorporate activatable, plastic-degrading microbes alongside the polymers.
The team used two bacterial strains that worked together and completely broke down the material within just six days, without making microplastics.
Researchers also pointed out that many microbes can break long polymeric chains into smaller pieces using enzymes. Because plastics are polymers, these enzymes or the microbes that make them could be incorporated into living plastics.
Turning plastic durability from a problem into a programmable feature
“By embedding these microbes, plastics could effectively ‘come alive’ and self-destruct on command, turning durability from a problem into a programmable feature,” said Zhuojun Dai, a corresponding author on the paper.
“The realization that traditional plastics persist for centuries, while many applications, like packaging, are short-lived, led us to ask: Could we build degradation directly into the material’s life cycle?”
The team also pointed out that plastics are extensively used, yet their resistance to degradation has led to severe environmental and ecological concerns. Recent advances in synthetic biology have enabled the development of spore-embedded living plastics.
Researchers stressed that living plastics can function when the spores are dormant and decay when the spores are activated. However, the degradation efficiency of individual Bacillus strain and the single-enzyme system remains limited.
Consortia-embedded living plastic
“To address this challenge, we engineered a consortia-embedded living plastic,” said researchers in the study.
“Bacillus subtilis are separately programmed with an inducible gene circuit capable of secreting two complementary plastic-degrading enzymes: Candida antarctica lipase, responsible for random-chain scission, and Burkholderia cepacia lipase, responsible for processive depolymerization and is stressed to sporulation.”
The team added that they further fabricated flexible, degradable electronic devices capable of detecting human electromyography signals using the consortia-based living plastics. Our method offers a potential strategy for tackling plastic pollution through programmed coordinated biological systems.
The team mixed the dormant spore form of B. subtilis with polycaprolactone (a polymer common in 3D printing and some surgical sutures) to protect the microbes before they were needed.
Wearable plastic electrode
The resulting living plastic had mechanical properties similar to those of plain polycaprolactone films. However, once a nutrient broth at 122 degrees Fahrenheit (50 degrees Celsius) was added, the spores activated, breaking the plastic all the way down to its base building blocks after just six days. The cooperation between the enzymes was so efficient, it even prevented microplastic particles from being created during the degradation process, according to a press release.
Researchers revealed that as a proof-of-concept, they created a wearable plastic electrode out of their living plastic and found it performed as expected, degrading completely within two weeks.
Researchers engineered Bacillus subtilis to produce two polymer degrading enzymes
In the future, researchers hope to develop a trigger for the spores in water, where a large portion of plastic pollution ends up. And though this work focused on just one polymer, a similar strategy could be used in other plastic types, including those commonly found in single-use plastics.
While previous attempts relied primarily on a single enzyme So, researchers engineered Bacillus subtilis to produce two cooperative, polymer-degrading enzymes. One enzyme acts as a random chopper, snipping the long polymer chains into smaller pieces, while the other slowly chews these pieces into their monomer building units from each end.
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Prabhat, an alumnus of the Indian Institute of Mass Communication, is a tech and defense journalist. While he enjoys writing on modern weapons and emerging tech, he has also reported on global politics and business. He has been previously associated with well-known media houses, including the International Business Times (Singapore Edition) and ANI.