Self-Degrading Plastics Inspired by Cellular Processes

Models of amino acids, which are the building blocks of enzymes

Innovation: Industry

Intropic Materials

Chemically Break Down Polymers

The vast majority of biochemical assembly and breakdown processes–even by the most complex organisms–occur within cells. In fact, cells are able to perform hundreds, even thousands of chemical transformations at the same time under life-friendly conditions (ambient temperature and pressure in an aqueous environment). For example, one of the biochemical pathways that break down proteins into their constituent amino acids is the protease enzyme-catalyzed processes that occur within the confined space of the lysosome–a membrane bound organelle in eukaryotic cells.

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Physically Break Down Non-living Materials

Nonliving materials are not carbon-based; that is, they are not and never have been living organs or tissues. However, they can be the products of living organisms, such as the calcium carbonate materials found in seashells (excluding organic compounds included in them). Physically breaking down nonliving materials requires mechanical means. While feeding, some living systems encounter very hard nonliving materials that can hinder access to the food. To address this, their teeth or other structures often contain minerals to maximize their hardness. For example, a marine organism called the chiton eats algae. But to access the algae, it must scrape it from rocks. To do so, it uses a special structure made of a material that’s stronger than the rock.

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Protect From Temperature

Many living systems function best within specific temperature ranges. Temperatures higher or lower than that range can negatively impact a living system’s physiological or chemical processes, and damage its exterior or interior. Living systems must manage high or low temperatures using minimal energy, which often requires controlling responses along incremental temperature changes. To do so, living systems use a variety of strategies, such as avoiding high or low temperatures, removing excess heat, and holding heat in. Insulation is a well-known example of managing low temperatures by retaining heat using thick layers of hair, fur, or feathers to hold warm air next to the skin.

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Protect From Light

Access to sunlight is crucial to living systems because it’s the primary energy source for life. However, too much sunlight in the form of ultraviolet radiation (UV) can cause damage to living tissues. Therefore, living systems have strategies to filter out some or all UV radiation. For example, some plants that live in areas exposed to long periods of direct sunlight have reflective surfaces (such as white hairs or powder) that reflect UV light.

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Protect From Chemicals

Chemicals are everywhere in the bodies of living organisms and their external environments. While most chemicals are valuable or benign, some are toxic, including those used for defense (such as the mucus that protects clownfish from an anemone’s stinging tentacles). Even naturally-occurring chemicals, such as arsenic, must be managed to reduce their impact. Some living systems have strategies to break down harmful chemicals, alter them into less toxic forms, physically prevent chemicals from harming sensitive tissues, and more. For example, some herbivorous mammals can digest toxic compounds in plants because they have a particular enzyme that helps them process poisonous plant compounds.

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Intropic Materials mimics the way chaperone proteins protect enzymes to create self-degrading plastics.

Benefits

Compostable
No microplastics

Applications

Plastic bags and bottles
Consumer goods
Clothing

UN Sustainable Development Goals Addressed

Goal 6: Clean Water & Sanitation
Goal 12: Responsible Production & Consumption
Goal 14: Life Below Water
Goal 15: Life on Land

The Challenge

Humans use plastics to make a wide range of products specifically because they are so strong, lightweight, and durable. But those same qualities prevent plastics––even compostable ones––from breaking down when they’re lost or discarded. As a result, huge quantities are polluting the water, land, and air, and becoming a health concern for all living beings on our planet.

There are microbes with enzymes that enable them to break down complex molecules like plastics, but microbes can attack only the surface of the plastics; and the chains are bound so tightly together, that only a few bonds are exposed for the enzymes to reach.

Humans could add natural enzymes directly to plastics to help break them down when the time comes, but the high heat and pressures of the manufacturing process can damage the sensitive enzymes before they’re able to do their work.

Innovation Details

Intropic Materials makes enzymatic embedding into plastics possible by chaperoning enzymes through the plastic production process inside protective biodegradable molecular covers. The covers keep the enzymes from breaking when the plastic is melted and extruded to form sheets or other shapes, but they don’t keep the enzymes from doing their job when the plastic’s useful life has ended.

When the plastic is exposed to composting conditions with sufficient heat and moisture for enough time, the enzymes effectively eat the plastic from the inside out, within hours or days––not simply breaking it down into microplastics, but disintegrating it back into simpler molecules. Those molecules can be recaptured and reused to make new plastics, or be broken down further by natural microbes in soil, or during water treatment.

Biological Model

Organisms of all kinds produce enzymes that can break down complex molecular chains. These molecular tools are precisely shaped to fit into the bonds between the monomers that make up a polymer. They then chemical reactions that unlock those bonds and break the chain back into separate links. In addition, specialized molecules called “chaperone s” fit together with enzymes to “switch them on” or move them where they need to be.

Ray of Hope Prize®

The Ray of Hope Prize celebrates nature-inspired solutions addressing the world’s biggest environmental and sustainability challenges. Created in honor of Ray C. Anderson, founder of Interface, Inc. and a business and sustainability leader, the $100,000 Ray of Hope Prize helps startups cross a critical threshold in becoming viable businesses by amplifying their stories and providing them with equity-free funding. The prize shines a light on the innovative, nature-inspired solutions that we need to build a sustainable and resilient world. Intropic Materials was selected as a finalist for the 2022 Ray of Hope Prize.

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