Long-range dispersion (Lifshitz-van der Waals) and short-range polar (hydrogen bonding) interactions are ubiquitous in physics, chemistry and biology. In this talk I will discuss their roles in two distinct systems, respectively surface-related and bulk-related. First, I will show how PC12 cells, a model for neuronal differentiation studies, respond to the surface energy landscape of their environment. Data indicate that they are highly sensitive to nanoscale chemical heterogeneities that can trigger cell adhesion and growth. These results provide new insight into how surface effects drive cell fate. Second, I will focus on the intermolecular interactions that define the material properties of nanofibrils of the prion protein, which is involved in lethal and infectious neurodegenerative diseases such as Creutzfeldt-Jacob disease in humans and mad cow disease in cattle. Specifically, I will show that fibrils formed by prions are relatively soft and clearly in a different class of rigidities when compared to nanofibrils formed by nonprions. This finding has far-reaching implications for the understanding of protein-based infectivity and the design of amyloid biomaterials.