Poly(lactic acid) nanoplastics through laser ablation: establishing a reference model for mimicking biobased nanoplastics in aquatic environments†

Due to the well-documented negative environmental impacts of conventional plastics, the use of bioplastics has been increasing. Poly(lactic acid) (PLA) is currently among the most common and industrially available bioplastics. Although PLA is compostable under industrial conditions and generally degrades more quickly than conventional plastics, its breakdown in typical environmental settings remains problematic. PLA's potential to contribute to plastic pollution, by releasing microplastics and nanoplastics, makes it crucial to understand how these particles behave, especially in marine environments. However, as for all nanoplastics, identifying, isolating, and quantifying PLA nanoplastics in water presents significant challenges. This study proposes a versatile approach to fabricate PLA nanoplastics through laser ablation in a water environment to mimic real-world samples. Commencing with bulk PLA films, this top-down method yields the formation of nanoplastics with an average diameter of 54.7 ± 26.7 nm. Surface and chemical analyses confirm the presence of carboxylic groups on their surface, potentially resembling the environmental degradation pathway of PLA under exposure to sunlight and humid environments. This indicates that the proposed process results in a PLA nanoplastics system that serves as an invaluable reference model, enabling realistic environmental scenario explorations and simulations for risk assessment evaluations on bio-based nanoplastics.