Modeling the bio-nano interactions of polypropylene nanoparticles

The environmental degradation of industrial and consumer plastics leads to the widespread presence of plastic micro- and nanoparticles in marine and terrestrial environments. Yet, their impacts on environmental safety and human health remain poorly understood. A key step in assessing these impacts is elucidating the bio-nano interactions that govern particle behavior in biological media. Here, we combine all-atom molecular dynamics with coarse-grained simulations to investigate protein adsorption and corona formation on polypropylene nanoparticles. The coarse-grain potentials are systematically derived from atomistic simulations of individual amino acids interacting with polypropylene fragments and surfaces. Using these potentials, we evaluated protein binding affinities on various polypropylene surfaces. Corona formation and composition are investigated using a kinetic Monte Carlo approach that mimics the competitive adsorption and desorption dynamics of proteins from a model solution. We show that the final corona composition reflects the relative binding energies and the number of favorable binding orientations of the competing proteins. Understanding the driving forces of adsorption and corona formation may help design safer polymeric materials and inform environmental risk assessment.