Assembling colloidal clusters using crystalline templates and reprogrammable DNA interactions

Abstract

Transient bridges of DNA have been used to direct the self assembly of microscopic spherical particles into a variety of crystal structures. Here, by selectively reprogramming the strength of the DNA interactions within such crystals we form colloidal clusters with well-defined valence and symmetry at high yield. We first form ‘host’ crystals containing a small proportion of ‘impurity’ particles bearing a unique DNA sequence, and then add soluble DNA strands that cause the host crystal to melt while preserving the nearest neighbor bonds around each impurity particle. This yields clusters with cubical and cuboctahedral symmetry from host crystals having BCC and FCC structures, respectively. Annealing of these clusters leads them to transform into lower free energy, but still highly symmetric forms, sometimes accompanied by the ejection of particles. The interactions between such clusters in principle could be further reprogrammed to allow hierarchical assembly processes.