Nanoplastics and microplastics released from an enzyme-embedded biodegradable polyester during hydrolysis

Embedding enzyme in biodegradable polyester accelerates hydrolysis in environments it ends up, but the release of microplastics (MPs) and nanoplastics (NPs) during this process remains underexplored. This work investigated the evolution of MPs and NPs released from poly(ε-caprolactone) (PCL) with embedded Lipase PS. The embedded enzyme significantly accelerated hydrolysis, causing the PCL film to disappear within 96 h. Notably, the formation rates and quantities of MPs and NPs were much higher compared to film with external enzyme. At 96 h, MPs (3.55 ×10 particles/mL) was 2.4 times, and NPs (4.65 ×10 particles/mL) was an order of magnitude higher than that with external enzyme. After 130 days, although both quantities and average size of MPs and NPs decreased due to only 90.6 % of enzymes were detected leaking, they did not completely disappear. The quantities of MPs and NPs were comparable to that with external enzyme, and the average size of MPs remained 1 μm. The simultaneous erosion inside film macroscopically, and severe chain cleavage microscopically, contributed to feasible film disintegration and formation of high amounts MPs and NPs. These findings underscore the importance of managing the release of MPs and NPs during the hydrolysis of enzyme-embedded biodegradable polyesters to ensure safety and mitigate environmental impact.