Spatial distribution of a depletion potential between a big solute of arbitrary geometry and a big sphere immersed in small spheres

The hypernetted-chain integral equations are solved on a three-dimensional cubic grid to calculate the spatial distribution of the depletion potential between a big solute of arbitrary geometry and a big sphere immersed in small spheres forming the solvent. By analyzing the potential along a specific trajectory of the big sphere, effects due to the geometric feature of the big solute (step edges, trenches, corners, changing curvature, etc.) can be examined in detail. As an illustration, effects of the step edge on the lateral depletion potential along a wall surface are analyzed. Along the trajectory considered, the big sphere moves at constant height, starting on the center of the wall surface and moving horizontally past the edge. The big sphere is repelled from the edge into the wall surface, and to escape to the bulk it must overcome a significantly high free-energy barrier. As another illustration, simple model calculations are performed for the lock and key steric interaction between macromolecules....

[1]  A. Minton,et al.  Macromolecular crowding: biochemical, biophysical, and physiological consequences. , 1993, Annual review of biophysics and biomolecular structure.

[2]  Evans,et al.  Depletion potential in hard-sphere mixtures: theory and applications , 2000, Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics.

[3]  Kaplan,et al.  Entropically driven surface phase separation in binary colloidal mixtures. , 1994, Physical review letters.

[4]  ENTROPIC FORCES IN BINARY HARD SPHERE MIXTURES: THEORY AND SIMULATION , 1997, cond-mat/9701086.

[5]  Dinsmore,et al.  Phase diagrams of nearly-hard-sphere binary colloids. , 1995, Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics.

[6]  Benoît Roux,et al.  NUMERICAL SOLUTION OF THE HYPERNETTED CHAIN EQUATION FOR A SOLUTE OF ARBITRARY GEOMETRY IN THREE DIMENSIONS , 1995 .

[7]  A. G. Yodh,et al.  Entropic control of particle motion using passive surface microstructures , 1996, Nature.

[8]  M. Cates,et al.  Depletion force in colloidal systems , 1995 .

[9]  A. Minton,et al.  Influence of excluded volume upon macromolecular structure and associations in 'crowded' media. , 1997, Current opinion in biotechnology.

[10]  P. Attard.  Spherically inhomogeneous fluids. II. Hard‐sphere solute in a hard‐sphere solvent , 1989 .

[11]  Fumio Oosawa,et al.  On Interaction between Two Bodies Immersed in a Solution of Macromolecules , 1954 .

[12]  Rosenfeld,et al.  Free-energy model for the inhomogeneous hard-sphere fluid mixture and density-functional theory of freezing. , 1989, Physical review letters.

[13]  G. Patey,et al.  Hypernetted‐chain closure with bridge diagrams. Asymmetric hard sphere mixtures , 1990 .

[14]  M. Ikeguchi,et al.  Direct numerical solution of the Ornstein–Zernike integral equation and spatial distribution of water around hydrophobic molecules , 1995 .

[15]  Masahiro Kinoshita,et al.  Depletion effects on the lock and key steric interactions between macromolecules , 2002 .

[16]  D. Frenkel,et al.  Depletion effects in binary hard-sphere fluids , 1996 .

[17]  M. Harada,et al.  Interaction between macroparticles in Lennard‐Jones fluids or in hard‐sphere mixtures , 1996 .

[18]  Philip Nelson,et al.  Hard Spheres in Vesicles: Curvature-Induced Forces and Particle-Induced Curvature , 1997, cond-mat/9710016.

[19]  S. Dietrich,et al.  DEPLETION FORCES IN FLUIDS , 1998 .