Fig. 3.

Interaction energies. (A) Schematic cross section of the area where DNA strands of hybridized length 2L can link between two spheres of radius R₀ with surface separation d.(B) Interaction energies as a function of surface separation d: U_dna from binding the accessible DNA strands, U_rep from the repulsive interaction due to electrostatics and/or polymer brushes, and U_vdW from the van der Waals attraction. (C) For weak, short-range U_rep, particles originally unbound at high temperatures are irreversibly trapped in the van der Waals well after DNA hybridization at low temperatures. (D) For strong, medium-range U_rep, DNA binding leads to a stable reversible energy minimum outside the van der Waals well.