(538b) Mechanisms for Controlled Dynamics in Gold Nanoparticle-DNA Origami Templates

Top-down fabrication techniques provide state-of-the-art, 2D, nano-sized electronic and photonic devices; however, these devices lack dynamic capacity to alter their physical structure in response to stimuli. However, bio-inspired, molecular recognition, bottom-up, self-assembly methods provide a platform not only for 3D assemblies, but potential dynamic motion. Deoxyribonucleic acid (DNA) origami is one such platform that relies on base pairing interactions in DNA to create 3D devices that can perform complex functions. These devices have been used as nano-robots, and also as templates for nanoparticle assembly. Unfortunately, strand invasion, the gold standard mechanism for controlled actuation of DNA origami structures, relies on slow de/rehybridization kinetics between DNA strands, with time scales ranging from minutes to hours. We hypothesized that DNA actuation could be improved by heating. Apart from external energy sources, the properties of nanoparticles, such as surface plasmon resonance in gold nanoparticles (AuNPs), can be harnessed for localized heating of DNA origami actuators.

Thus, we investigated fundamental interactions between NPs and DNA origami structures with the goal of understanding energy transfer and kinetics between these structures. In this study, we employed a DNA origami hinge decorated with AuNP. The hinge arms were modified at specific mirror locations with single stranded (ss)-DNA overhangs complementary to ss-DNAs bound to AuNPs. Thus, binding of AuNPs, closed the hinges. Initially, the free energy landscape for closed hinges with AuNPs in varying locations was evaluated using Transmission Electron Microscopy (TEM). To evaluate the kinetics of AuNP-hinge opening in response to heating, hinges were modified with Förster Resonance Energy Transfer (FRET) reporters that indicated NP binding and hinge closure, respectively. Kinetics was then evaluated using fluorescence spectroscopy. Localized actuation was induced by laser actuation of AuNPs, which dissipates the optical input in the form of local heat. We compared these results to those obtained via bulk heating method. Bulk heating decreased time scales for actuation, which were limited only by heat transfer. We are currently evaluating the kinetics of structures undergoing local, plasmonic heating. This research could provide a strategy for increasing actuation kinetics in DNA origami structures, paving the way for light-sensitive, higher-order composites for potential nano-photonic applications.