The entropic impact of tethering, multivalency and dynamic recruitment in systems with specific binding groups

This Highlight Article discusses the important yet frequently overlooked entropic effects in soft matter systems that have one or more tethered binding groups. We show that the effective interactions depend sensitively on a combination of configurational, combinatorial and translational entropy factors, which have to do with the tethering of the binding groups, the binding state multiplicity in multivalent systems, and the dynamic recruitment of surface-mobile binding groups. Importantly, these entropic effects can give rise to qualitatively new behavior, e.g. in the phase behavior of DNA-functionalized colloids or in the targeting of ligand-functionalized nanoparticles to cell receptors. A better understanding of the thermodynamics of tethered (multivalent) bond interactions thus impacts a wide range of fields, including soft materials science, biophysics, nanomedicine and biosensing, supramolecular and colloidal self-assembly, and nanofabrication.