Facile preparation of environmentally relevant nano- and microplastics for hazard assessment and ecotoxicological testing evaluation

For years, a large proportion of plastics has been left behind in the environment and deteriorate in the form of nano- and microplastics (NMPs). These NMPs interact with living organisms. However, there are no established methods with which these NMPs can be reproduced, so their systemic study is limited. In this work, PET (polyethylene phthalate) nano- and microparticles are produced from commercially available polymer pellets by different grinding processes (top-down approach) that simulate environmental weathering. The developed process enables the production of plastic particles in the range of 20 nm to 300 μm in stable suspensions and free of impurities such as endotoxins. Relevant changes are detected in the NMPs related to the reduction of the particle size, their structural amorphization and the hydroxylation of the surface, which leads to an increase in the electrostatic charge affecting their stability in aquatic environment. This method allows the systematic study of plastic NMPs whose size and morphology are similar to those produced by erosion and transport in the environment. Down-streaming use of these suitable test materials for in vitro biological determinations related to human risk assessment is also evidenced in this work.