Abstract
DNA-coated colloids hold great promise for self-assembly of programmed heterogeneous microstructures, provided they not only bind when cooled below their melting temperature, but also rearrange so that aggregated particles can anneal into the structure that minimizes the free energy. Unfortunately, DNA-coated colloids generally collide and stick forming kinetically arrested random aggregates when the thickness of the DNA coating is much smaller than the particles. Here we report DNA-coated colloids that can rearrange and anneal, thus enabling the growth of large colloidal crystals from a wide range of micrometre-sized DNA-coated colloids for the first time. The kinetics of aggregation, crystallization and defect formation are followed in real time. The crystallization rate exhibits the familiar maximum for intermediate temperature quenches observed in metallic alloys, but over a temperature range smaller by two orders of magnitude, owing to the highly temperature-sensitive diffusion between aggregated DNA-coated colloids.
Highlights
DNA-coated colloids hold great promise for self-assembly of programmed heterogeneous microstructures, provided they bind when cooled below their melting temperature, and rearrange so that aggregated particles can anneal into the structure that minimizes the free energy
We show how the crystallization kinetics is controlled by the sensitive temperature dependence of the surface diffusion of colloids bound by hybridized DNA
While we employ colloids made from a variety of materials, including poly(styrene), poly(methyl methacrylate) and silica, we focus our discussion on DNA-coated colloids made from 3-(trimethoxysilyl) propyl methacrylate (TPM)
Summary
DNA-coated colloids hold great promise for self-assembly of programmed heterogeneous microstructures, provided they bind when cooled below their melting temperature, and rearrange so that aggregated particles can anneal into the structure that minimizes the free energy. We show that these problems can be addressed by fabricating particles with a high grafting density of singlestranded DNA (ssDNA), 5 to 25 times greater than previously reported[10,22,23], smooth surfaces and short DNA sticky ends, with as few as four bases. These factors enable bound particles to roll over each other near the DNA melting temperature so that the particles can find their free energy minimum and form very large crystals. We are able to follow the annealing process, including how various kinds of defects form
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