A chemically modified enzyme helped break down used PLA plastic in a heated ionic liquid, offering a laboratory route to recover the material’s building blocks. In the reported experiments at 90°C, the plastic became fully water-soluble within 24 hours, while complete conversion to lactic acid took up to 40 hours.
Susana M. Meza Huaman, Jake H. Nicholson and Alex P. S. Brogan at King’s College London described the work in Cell Reports Physical Science. The material tested was poly(lactic acid), or PLA, including fragments of a used plastic cup.
Changing the enzyme’s working environment
The team used lipase B from Candida antarctica, often abbreviated CaLB. They chemically modified the enzyme’s surface and associated it with a surfactant so that it could function in an ionic liquid. This was a chemical treatment of the protein, rather than a change to the gene encoding it.
The liquid, 1-ethyl-3-methylimidazolium acetate, helped make PLA accessible to the catalyst. Enzyme treatment and solvent choice worked together: the result should not be described as an enzyme dissolving a discarded cup under ordinary environmental conditions.
Why heat resistance mattered
A later account from Diamond Light Source, published in January 2025, explains the structural measurements used in the work. Circular dichroism experiments on its B23 beamline examined whether the modified enzyme retained its folded structure and how it responded to heating.
That matters because the reaction environment must suit both the plastic and the enzyme. Heating can make a polymer easier to attack, but it can also damage the catalyst. Stabilising the protein helps address that tension.
Disappearance is not the same as recovery
The 24-hour and 40-hour results describe different endpoints. Making solid plastic water-soluble is not the same as converting its chains completely into individual lactic acid molecules. The researchers assessed monomer formation separately.
This distinction is useful when reading any enzyme-recycling claim. A material can lose mass or fragment without yielding a purified raw material ready for reuse. The evidence becomes stronger when the products, conversion and conditions are reported together.
What would make this a recycling process?
The practical question is what happens after the reaction. A recycling operation would need to separate a useful product, manage the solvent and catalyst, and handle variable waste streams. Its overall performance would depend on those steps as well as the speed of depolymerisation.
The experiment provides a route worth investigating. It does not establish lower costs or a smaller total environmental footprint. Comparing its reaction time with composting alone would also miss an important difference: the processes aim at different end products.
For the broader evidence behind plastic-degrading enzymes, see our guide to the PAZy database.
Sources
Meza Huaman, S. M., Nicholson, J. H. and Brogan, A. P. S. (2024). A general route to retooling hydrolytic enzymes toward plastic degradation. Cell Reports Physical Science, 5(2), 101783. Read the study.
Diamond Light Source (14 January 2025). Research-facility account of the structural measurements. This later source describes the same 2024 study.
Update note: This archived report retains its original publication date and URL. The revision distinguishes solubilisation from monomer conversion, gives the reaction temperature and identifies the later supporting source separately.
