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

Area of Science:

• Polymer Science
• Environmental Science
• Materials Chemistry

Background:

• Biodegradable polyesters offer a sustainable alternative to conventional plastics.
• Enzyme-mediated hydrolysis accelerates the degradation of these materials.
• The release of microplastics (MPs) and nanoplastics (NPs) from degrading polymers is an emerging environmental concern.

Purpose of the Study:

• To investigate the formation and evolution of MPs and NPs during the hydrolysis of enzyme-embedded poly(ε-caprolactone) (PCL).
• To compare the release of MPs and NPs from PCL with embedded enzymes versus external enzymes.
• To assess the long-term fate of MPs and NPs generated from enzyme-embedded PCL.

Main Methods:

• Embedding Lipase PS enzyme within PCL films.
• Monitoring PCL film disappearance and hydrolysis rates.
• Quantifying MPs and NPs using particle counting techniques over time.
• Analyzing the size distribution of MPs and NPs.

Main Results:

• Embedded enzyme accelerated PCL hydrolysis, causing film disappearance within 96 hours.
• Significantly higher quantities of MPs (2.4x) and NPs (10x) were released from embedded-enzyme PCL compared to external-enzyme PCL at 96 hours.
• MPs and NPs persisted after 130 days, with quantities comparable to external-enzyme samples and an average MP size of 1 μm.

Conclusions:

• Enzyme embedding in biodegradable polyesters leads to substantial MPs and NPs release.
• Both macroscopic erosion and microscopic chain cleavage contribute to polymer disintegration and particle formation.
• Managing MPs and NPs release is crucial for the environmental safety of enzyme-embedded biodegradable materials.