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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 24: Poster Session I

CPP 24.1: Poster

Montag, 16. März 2020, 17:30–19:30, P3

Multivalent Cation-Induced Actuation of DNA-Mediated Colloidal Superlattices — Devleena Samanta^1,3, •Aysenur Iscen², Christine R. Laramy^2,3, Sasha B. Ebrahimi^2,3, Katherine E. Bujold^1,3, George C. Schatz^1,3, and Chad A. Mirkin^1,2,3 — ¹Department of Chemistry — ²Department of Chemical and Biological Engineering — ³International Institute for Nanotechnology, Northwestern University, Evanston IL USA

Nanoparticles functionalized with DNA can assemble into ordered superlattices with defined crystal habits through programmable DNA “bonds”. Here, we examine the interactions of multivalent cations with these DNA bonds as a chemical approach for actuating colloidal superlattices. Multivalent cations alter DNA structure on the molecular scale, enabling the DNA “bond length” to be reversibly altered between 17 and 3 nm, ultimately leading to changes in the overall dimensions of the micron-sized superlattice. The identity, charge, and concentration of the cations each control the extent of actuation, with Ni²⁺ capable of inducing a remarkable >65% reversible change in crystal volume. Molecular dynamics simulations provide insight into the conformational changes in DNA structure as the bond length approaches 3 nm and show that cations that screen the negative charge on the DNA backbone more effectively cause greater crystal contraction. Taken together, the use of multivalent cations represents a powerful strategy to alter superlattice structure and stability, which can impact diverse applications through dynamic control of material properties, including the optical, magnetic, and mechanical properties.