CM-AMO Seminar | Using DNA to Program Pathways in Colloidal Self-Assembly

DNA is not just the stuff of our genetic code; it is also a means to build materials. Grafting DNA onto colloidal nano- and microparticles can, in principle, ‘program’ them with information that tells them exactly how to self-assemble. Recent advances in our understanding of how this information is compiled into specific interparticle attractions have enabled the assembly of crystal phases not found in ordinary colloids, and could be extended to the assembly of prescribed, nonperiodic structures. However, structure is just one piece of a more complicated story; in actuality, self-assembly describes a phase transition between a disordered state and an ordered state, or a pathway on a phase diagram. In this talk, I will present experiments showing that the information stored in DNA sequences can be used to design the entire self-assembly pathway, and not just its endpoint. Using free DNA strands that either link together strands grafted to particles or compete to bind with them, I will show that it is possible to create colloids with new types of phase behavior, such re-entrant melting, temperature-independent coexistence, and reversible transitions between different solid phases. Going forward, this work could prove especially useful in nanomaterials research, where a central goal is to manufacture functional materials that can respond or reconfigure on demand.