Solid Colloids with Surface-Mobile DNA Linkers

Abstract

Surface functionalization with bioinspired binding groups is increasingly used to steer nano- and microscale self-assembly processes, with complementary DNA "sticky ends" as one of the most notable examples. The fabrication of well-organized structures is complicated, however, by the sharp association/dissociation transitions and the slow rearrangement kinetics intrinsic to collections of discrete, surface-immobilized binding groups and is aggravated by natural nonuniformities in the surface coating. Here, we demonstrate a novel system of solid microparticles functionalized with specific binding groups-in this case DNA linkers-that are fully mobile along the particle surface. These colloids display qualitatively new behavior and circumvent many of the commonly encountered issues. Importantly, the association/dissociation transition, and thereby the temperature window for equilibrium self-assembly, is much broader. We further find that the linkers are uniformly distributed above the DNA melting temperature, while visibly accumulating at the interparticle contacts below this temperature. The unique combination of binding group mobility with nondeformability, monodispersity, and facile manipulation of solid particles should have a profound impact on DNA-mediated and other bioinspired self-assembly approaches. Moreover, our highly tunable experimental system enables detailed model investigations that will also deepen our fundamental understanding of other systems with surface-mobile binding groups, for instance, biological ligand-receptor interactions.

Entropy Stabilizes Floppy Crystals of Mobile DNA-Coated Colloids

“…By using DNA-coated colloids (DNACCs), a number of ordered crystals [4-10] and selfassembled "colloidal molecules" [11] have been obtained in experiments, while the self-assembly mechanism of DNACCs is still not well understood [9,12,13]. For example, the diffusionless transformation from a floppy crystal to the other compact crystal has been observed in experimental systems while the underlying mechanism remains not fully resolved [13].Recently, a novel system of mobile DNA-coated colloids (mDNACCs) was introduced that displays qualitatively new properties [14,15]. Compared with immobile DNA-coated colloidal systems, mDNACCs have a broader temperature window for self-assembly, and therefore allow the better control over the assembly process [14].…”

“…Compared with immobile DNA-coated colloidal systems, mDNACCs have a broader temperature window for self-assembly, and therefore allow the better control over the assembly process [14]. Mobility of DNA linkers also allows particles to more easily roll around each other and rearrange [14,16], without grafting of very high density.…”

“…Then using βU = βF att + βF rep above, we perform extensive Monte Carlo simulations for systems of N ≈ 500 mDNACCs; and by free energy calculations [21], we construct the phase diagrams in both 2D and 3D. In our 2D system of mDNACCs, colloids are moving in a 2D plane while DNA linkers rotate in a 3D space, which can model the selfassembly of mDNACCs at the bottom of an experimental chamber [13,14] or the liquid-liquid interface [22]. Figure 1 shows phase diagrams in the area/packing fraction η -binding strength β∆G 0 representation for mDNACC systems in 2D and 3D, respectively.…”

Application of nucleic acid–lipid conjugates for the programmable organisation of liposomal modules

“…Therefore endfunctionalised cholesterol-DNA amphiphiles (chol-DNA), in general, appear to be more compliant for bionanotechnology and soft materials applications. Very recently, double-cholesterol modified DNA has been used to functionalise lipid bilayer supported on microscale silica colloids, which brings the advantageous property of DNA lateral surface mobility to the assembly of hard, inorganic colloidal materials [62].…”

Mobile Linkers on DNA-Coated Colloids: Valency without Patches

“…Such colloids have been previously synthesized in various ways, as described in Refs. [14,15]. When the suspension is cooled below a specific (sequence-dependent) temperature, the ssDNA will hybridize with its complement, forming bonds between the DNACCs.…”