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 approximate to 4 at average volume fraction of crowders phi(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 phi(c) approximate to 0.145.
Theory of molecular crowding in Brownian hard-sphere liquids / A. Zaccone, E. Terentjev. - In: PHYSICAL REVIEW E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS. - ISSN 1539-3755. - 85:6(2012), pp. 061202.1-061202.8.
Theory of molecular crowding in Brownian hard-sphere liquids
A. Zaccone
;
2012
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 approximate to 4 at average volume fraction of crowders phi(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 phi(c) approximate to 0.145.File | Dimensione | Formato | |
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