(708c) Efficient Predictions of Solvent-Mediated Interactions By Classical Density Functional Theory

The solvent-mediated interaction, or equivalently the depletion force, play pivotal role in the processes, by which the two objects in solution, such as nanoparticles, lock and key molecules, antibody and antigen, macromolecule and substrate, are attracted to each other. The quantification of this interaction is important yet challenging since it depends on the microscopic solvent density in the surrounding. Here, we show that the solvent-mediated interaction can be efficiently predicted by combining classical density functional theory and a reversible thermodynamic circle. For demonstration, the solvent-mediated interactions in three difference cases, namely, nanoparticle with nanoparticle, nanoparticle with a flat smooth wall, and nanoparticle with a rough wall, are investigated, and the good agreements compared with the results from parallel simulations are achieved, validating our approach. Thereafter, we examine the reported self-assembly phenomena of lock and key colloidal particles in the presence of depletant in different concentrations and temperatures (Nature, 464, 25 March 2010), and successfully characterize the binding probability between the lock and key colloids. This approach provides an efficient route for identifying the coarse-graining interaction between two objects in solution.