Measuring Molecular Forces With Atomic Force Microscopy 1: Solvent Influence on Hydrophobic Interactions

Molecular forces drive phenomena such as self-assembly, aggregation, and protein folding, where hydrophobic interactions are paramount. However, the origin of the hydrophobic mechanism remains unknown. Advances in techniques like atomic force microscopy (AFM) have improved our ability to study this topic. Hydrophobic interactions are stronger and longer ranged than van der Waals (vdW) forces, potentially arising from water structuring, polarization, and entropic effects. In this primer, fluorocarbon surfaces were prepared via chemical vapor deposition (CVD) on gold to explore the impact of water:DMSO solvent binary mixtures on hydrophobic interactions. Force-distance curves measured with AFM were fitted to an extended vdW model, disclosing the influence of the medium polarity on the interactions.