Interfacial selectivity is central to catalysis and biomedical imaging. Nanoparticles with desirable properties (optical, electronic, catalytic) are often available, but face challenges in complex chemical environments with a variety of substrates. Restricting access to these surfaces using soft functionalizations (polymers, DNA, surfactants) has been successful in developing selective carbon-nanotube sensors, but designing the selectivity a priori remains a challenge. Prof. Ulissi uses molecular simulations and thermodynamic models to study interfacial packing and selectivity at these interfaces.