A simple theory for interfacial properties of dilute solutions

Area of Science:

• Thermodynamics
• Statistical Mechanics
• Physical Chemistry

Background:

• Cosolute mixtures can non-additively affect protein stability.
• Liquid-vapor interfaces offer insights into these non-additive effects.

Purpose of the Study:

• Relate interfacial properties of dilute multicomponent solutions to solute interactions.
• Develop a theory to derive thermodynamic observables from microscopic interactions.

Main Methods:

• Derived a model for surface excess of solutes using thermodynamic observables.
• Developed a lattice-based statistical mechanical perturbation theory (Dilute Solution Theory - DST).
• Used Monte Carlo (MC) simulations to validate DST against regular solution theory.

Main Results:

• DST accurately describes solute interactions in dilute solutions, outperforming regular solution theory.
• DST distinguishes between intrinsic and effective solute preferences for interfaces.
• Identified three classes of solutes based on their interfacial preferences, with interactions modulating their behavior.

Conclusions:

• DST provides a more accurate description of dilute solutions than regular solution theory.
• Solute-solute interactions significantly influence interfacial behavior and protein stability.
• DST can be extended to include surface polarization and model experimental data.