Biological Evaluation of Binding of Toxins to Microplastics

Micro- and nanoplastics (MNPs) contaminate ecosystems worldwide and enter our food and water via the aquatic environment or plastic food containers. MNPs could serve as carriers of aquatic or food pathogens and/or their toxins, facilitated by their large surface area and hydrophobic nature. However, there is currently no method for qualitative or quantitative evaluation of toxin binding to MPs. This study focuses on cereulide (CER) and fumonisin B1 (FB1) as model toxins, examining their binding to microplastics (MPs) composed of polyethylene terephthalate (PET) and polypropylene (PP) under simulated environmental and biological conditions. It aims to evaluate the binding of toxins to MPs by assessing the subsequent biological effects using advanced cell-based models and analysis techniques. The work is part of the EU-funded IMPTOX project, aiming to unravel the mechanisms of MP-toxin interactions and their implications for human exposure and toxicity. An optimized 3D in vitro cell model assisted in exposing hepatic HepG2 spheroids to the different conditions. The spheroids were chronically exposed to MPs that were pre-incubated for 2 hours with the toxins. Using IncuCyte Sx5 Live Cell Analysis and Agilent Seahorse extracellular flux analysis, the cells' bioenergetic responses were monitored. Shifts in metabolic parameters for bound toxin-MPs versus the MPs or toxins alone indicate that this biological approach could serve as an effective proxy to investigate toxin-MP binding. This research has been funded by IMPTOX European Union s Horizon 2020 research and innovation program (grant number 965173), Research Foundation Flanders research grant 1506419N, Ghent University Special Research Fund grant BOF20/BAS/120, The Federal Public Service (FPS) Health, Food Chain Safety and Environment project RT 21/5 CYANTIR and Research Foundation Flanders/ Slovenian Research and Innovation Agency Weave project with grant number G000123N. M.F.A. received a postdoctoral mandate funded by Ghent University Special Research Fund (BOF) grant number BOF01P03220.