On the difference of equilibrium constants of DNA hybridization in bulk solution and at the solid-solution interface

The origin of the difference between the equilibrium (affinity) constants of ligand-receptor binding in bulk solution and at a solid-solution interface is discussed in terms of Gibbsian interfacial thermodynamics. It results that the difference is determined by the surface work that the ligand-receptor interaction spends to accommodate surface binding, and in turn that the value of the surface equilibrium constant (strongly) depends on the surface that confines the event. This framework consistently describes a wide set of experimental observations of DNA surface hybridization, correctly predicting that within the surface work window for DNA hybridization, that ranges from -90 to 75 kJ mol(-1), the ratio between surface and bulk equilibrium constants ranges from 10(-16) to 10(13), spanning 29 orders of magnitude.