title: Theory of molecular crowding in Brownian hard-sphere liquids.
abstract: We derive an analytical pair potential of mean force for Brownian molecules in the liquid state. Our approach accounts for many-particle correlations of crowding particles of the liquid and for diffusive transport across the spatially modulated local density of crowders in the dense environment. Focusing on the limit of equal-size particles, we show that this diffusive transport leads to additional density- and structure-dependent terms in the interaction potential and to a much stronger attraction (by a factor of ≈4 at average volume fraction of crowders φ{0}=0.25) than in the standard depletion interaction where the diffusive effects are neglected. As an illustration of the theory, we use it to study the size of a polymer chain in a solution of inert crowders. Even in the case of an athermal background solvent, when a classical chain should be fully swollen, we find a sharp coil-globule transition of the ideal chain collapsing at a critical value of the crowder volume fraction φ{c}≈0.145.
authors.affiliation: Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom.
authors.forename: Alessio
authors.initials: A
authors.lastname: Zaccone
authors.forename: Eugene M
authors.initials: EM
authors.lastname: Terentjev
mesh_terms: D003198:Computer Simulation; D004058:Diffusion; D008956:Models, Chemical; D009038:Motion; D053758:Nanoparticles / Q000737:chemistry*; D012996:Solutions / Q000737:chemistry*
chemical_list: D012996:Solutions