In the field of engineering, the hydrophobicity (or dewetting ability) of a flat surface (e.g., a counter top in kitchen or a cooking pan) can be measured by the contact angle of water droplet. A University of Nebraska-Lincoln team recently devised a computational approach that can relate the molecular hydrophobicity scale of amino-acid chains to the contact angle of water nanodroplet. The team constructed planar networks composed of unified amino-acid side chains with native structure of the beta-sheet protein. Using molecular dynamics simulation, the team is able to measure the contact angle of water nanodroplet on the planar networks (caHydrophobicity).
On the other hand, previous studies show that the minimum of excess chemical potential of a hard-sphere solute with respect to that in the bulk exhibits a linear dependence on cosine value of contact angle. Based on the computed excess chemical potentials of the purely repulsive methane-sized Weeks–Chandler–Andersen solute with respect to that in the bulk, the extrapolated values of cosine value of contact angle are calculated(ccHydrophobicity), which can be used to quantify the hydrophobicity of amino acid side chains with complete wetting behaviors.