Linker-mediated self-assembly of mobile DNA coated colloids

An immense challenge in materials sciences is to find a way to construct materials with absolute control over the placement of each building block to tailor properties for given applications. DNA coated colloids offer the possibility of realizing programmable self-assembly, which in principle can assemble almost any structure in equilibrium, while remains challenging experimentally. Here we propose a new system of linker-mediated mobile DNA coated colloids (mDNACCs), in which the interaction between mDNACCs is induced by the bridging of free DNA linkers in solution, whose two single stranded DNA (ssDNA) tails can bind with specific ssDNA receptors of complementary sequence coated on the colloids. We formulate a mean field theory to efficiently calculate the effective interaction between mDNACCs mediated by free linkers, in which the entropy of DNA linkers plays a non-trivial role. Especially, when the binding between free linkers in solution and the corresponding receptors on mDNACCs is very strong, the linker-mediated colloidal interaction is determined by the linker entropy, which depends on the concentration of free linkers. As the concentration of free linkers can be precisely controlled in experiments, this suggests a new way for experimentally designed assembly of DNACCs.