Molecular modelling approaches to investigate bio-nano interfaces and the interactions with inorganic matter

The rapid development of nanotechnology has strongly encouraged the scientific research in the field of manufacturing, characterization and use of nanoparticles (NPs). Indeed, it has become very important to define the impact of NPs on the environment and human health in order to establish shared rules on their use. This thesis work is included in the framework of the European project NanoinformaTIX (Grant agreement n. 814426), whose objective is to apply the materials modelling techniques to advance the sustainable design of NPs. Specifically, the aim of this thesis carried out in the University of Leiden, Institute of Chemistry/Energy & Sustainability is to deepen and study the behaviour of nanoparticles in a bio-compatible medium, using computational modeling tools, which represents a convenient alternative to experimental measurements. Among the most interesting and promising bio-materials in therapeutic and diagnostic applications, gold should be definitely mentioned. First, different models of gold NPs were created. Then, the interaction of a gold NP with a polymer chain was analyzed, specifically, the Poly(Lactic-co-Glycolic Acid) (PLGA) copolymer, which is widely used to coat gold nanoparticles and make them bio-compatible. The free energy profile obtained with the umbrella sampling method has shown the spontaneous absorption of the copolymer on the surface of the gold NP. Finally, by tuning the concentration of the PLGA in an aqueous environment, the self-assembly phenomenon of PLGA was simulated and observed with consequent absorption of polymer clusters on the gold NP. The modeling study conducted within this thesis offers an accurate methodological approach to understand and predict the behaviour of gold nanoparticles with potential use in the biomedical field.