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From microplastics clogging up our oceans to landfills leaching dangerous chemicals, plastic waste is a serious and growing problem for human health and the environment. We need to recycle more and, crucially, recycle better.
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Most plastic that is recycled is melted and remolded into lower-quality products such as carpet fibers and garden planters before eventually ending up in a landfill or an incinerator. This is downcycling rather than proper recycling. Current methods don't enable the recovery of the original components of the waste—that means they cannot be truly recycled into new, high-quality plastic.
A 2026 study in Angewandte Chemie International Edition from the University of Manchester marks a potential turning point in our ability to recycle better. The study focused on polycarbonate, a type of hard plastic. These plastics are common but notoriously difficult to degrade because they are specifically designed for strength and durability in safety glasses, electronics and machine parts.
The Manchester authors report a way to rapidly digest polycarbonate back to its original building blocks. They did this by creating an enzyme (proteins that carry out chemical reactions) to digest the polycarbonate. This is part of a major emerging field that uses super-enzymes for green recycling of our waste.
Enzymes are nature's nanomachines: They speed up reactions to make and break chemical bonds, converting one compound into another. For example, digestive enzymes can break starch in bread back into the simple sugars from which it is made. If enzymes could similarly digest plastic into its original building blocks, those blocks could then be reused to synthesize new plastic. It would be a double win: less waste and a drastic decrease in the need to extract crude oil to manufacture new plastic.
However, there are two big problems. First, plastics need heating to around 70°C (158°F) to open up their structures enough for the enzymes to get at the chemical bonds that hold them together. But enzymes are proteins, and proteins get destroyed by heat. Think of the way the clear protein in your egg white solidifies and permanently changes as it hits the pan. The other issue is that enzymes have evolved to work on natural compounds, not human-made synthetics.
Ancient evolution can help with the heat problem. Some microbes, called extremophiles, live at temperatures of more than 100°C (212°F), in volcanoes and deep-sea hot springs. To be able to do this, their proteins have evolved special features that make them heat-resistant. These include a rigid outer shell and lots of high-strength bonds between different parts of the protein, acting like steel girders to reinforce the structure against the effects of heat. These evolutionary innovations give us a blueprint for making our plastic digesters heat-resistant.
That still leaves the difficulty of how to get enzymes to work on synthetic materials. Here we can turn to some of the tricks used by protein engineers like me.
One approach is directed evolution, a way of breeding better proteins through repeated mutation and selection, just like natural evolution but compressing that process in the lab into just a few weeks. Directed evolution can train proteins to work on plastics rather than their natural substrates, and this was a key method used by the Manchester group for their polycarbonate digester.
Supercharging with AI
Artificial intelligence can supercharge the process of protein and enzyme design. By training machine learning models to analyze millions of existing proteins, correlations between the specific functional activity of each protein and the structural features that make up that protein can be mapped. The computer can then predict what structural features we need to introduce or modify in our starting protein to achieve a particular target function.
Combining strategies like directed evolution and AI, and adding the hacks for heat resistance learned from extremophiles, lets scientists build super-enzymes that are stable at 70°C (158°F) and trained to digest plastics and spit out the very components needed to make a truly circular plastic economy.
Using super-enzymes for green recycling is on the horizon for other types of waste as well, including synthetic textiles, electronics and even astronaut waste deep in space. By looking back to ancient evolution and combining this with the latest lab evolution and AI, we could improve our future, potentially changing plastic waste from a problem into a resource.
More information: Henry A. Jones et al, Directed Evolution of an Efficient Polycarbonate Depolymerase With Exceptional Operational Stability, Angewandte Chemie International Edition (2026). DOI: 10.1002/anie.202525215
This article is republished from The Conversation under a Creative Commons license. Read the original article.
This story was originally published on Phys.org.
