In recent years the evidence of the presence of small (micro and nano scale) plastic particles in the natural environment is increasing. Their interaction with cell membranes is key to determine their toxicity on living organisms, but the physical driving forces and the molecular mechanisms underlying nanoplastic-membrane interactions are still largely unknown. Computer simulations with atomistic resolution, focused on the interaction between plastic nanoparticles and cell membranes, are challenging, due to the large number of atoms (order of 1 million) and to the time scales involved (tens of microseconds). One way to address the problem is to work with coarse-grained models, where a single particle represents a group of atoms, reducing substantially the number of degrees of freedom of the system and speeding up its dynamics.
In this thesis we will develop an original coarse-grained model of an every-day use polymer, polystyrene, and study its interactions with model lipid membranes. The development of coarse-grained models of polymer molecules requires learning and progressively mastering fundamental concepts in soft matter, thermodynamics and statistical physics (polymer scaling laws, thermodynamic potentials, etc.).
Advanced computational skills are not a strict requirement, as these technical competences can be easily acquired during the early stages of the work, which will be performed in the framework of a direct collaboration with the developers of the most popular biomolecular coarse-grained model worldwide, the Martini model (group of S.J. Marrink, University of Groningen, Netherlands, http://cgmartini.nl/). We will rely on the use of the most advanced Molecular Dynamics-based simulation techniques, including techniques for the advanced sampling of free energy landscapes. Simulations will be run both on in-house and on national and international supercomputing facilities.