NANOPLAST

Every year, millions of tons of plastic litter are reversed into the oceans, washed up on the shores or piled in landfills. There, plastics are degraded down to the micro and nano scale, and enter the food chain. Plastic particles can transport toxic substances, but the effects of micro and nanoplastics themselves on living organisms is still largely unknown. Here we address a key step of this interaction: the interaction of nanoplastics with model biological membranes. We propose a computational study of the interaction between polymers of everyday use and model lipid membranes. Our main goal is to identify possible physical mechanisms of damage to the cell membrane induced by the interaction with plastic nanofragments. Membranes can be altered in many ways: mechanical (membrane rigidity), dynamical (lipid and peptide diffusion) and structural (lipid order, area per lipid, membrane thickness). Even more interestingly, our preliminary results show that hydrophobic polymers such as polystyrene can influence the lateral organization of heterogeneous lipid membranes into ordered (rafts) and disordered domains. These changes are relevant as they can affect the functionality of membrane proteins and other constituents, therefore altering the overall cell functioning. We will study the polymers most commonly found in the marine environment (polypropylene, polyethylene, polyethylene terephthalate, polystyrene…) and model membranes of various compositions. We will model both the polymers and the membranes at a coarse-grained level, relying on the support of detailed all-atom models whenever necessary. Characterizing the interaction of plastic nanoparticles with cell membranes is the first step towards understanding the physical and chemical basis for their toxicity in all living organisms – bacteria, plants and animals. Since plastics are nowadays ubiquitous, the project can have a great impact, on the scientific community worldwide and on the society in general.