Colloidal Crystals Engineered with DNA from Supramolecular Programmable Atom Equivalents with Stimuli-Responsive Cores.

Oligonucleotide-functionalized nanoparticles (NPs), known as "programmable atom equivalents" (PAEs), are the primary building blocks for the field of colloidal crystal engineering with DNA. With these constructs, one typically uses canonical DNA-DNA interactions to control the colloidal crystallization process. Herein, DNA-modified perylene diimides that can assemble into spherical micellar PAEs are synthesized and characterized. These PAEs are held together via noncovalent interactions, and therefore both chemical and physical stimuli can be used to disassemble them and, consequently, modulate the structures of colloidal crystals made from them. When combined with gold nanoparticle PAEs of approximately the same size but with complementary DNA, these micellar PAEs assemble into BCC colloidal crystal lattices. Electron microscopy, UV-vis spectroscopy, and synchrotron small-angle X-ray scattering studies confirm the structural assignment. Spectroscopic and microscopy studies show that anionic aromatic molecules (1,3,6,8-pyrenetetrasulfonate) are capable of disrupting the supramolecular PAEs, which leads to disassembly of the colloidal crystal lattice. Molecular dynamics simulations and first-principles calculations provide further insight into the PAE core assembly process and notably suggest that it is independent of DNA valency and sequence. This work is important because it introduces a new strategy and extralattice chemical parameter for controlling colloidal crystals engineered with DNA.