Shape Changing Thin Films Powered by DNA Hybridization
Active materials that respond to physical and chemical stimuli can be used to build dynamic micro-machines that lie at the interface between biological systems and engineered devices. In principle, the specific hybridization of DNA can be used to form a library of independent, chemically-driven actuators for use in such micro-robotic applications and could lead to device capabilities that are not possible with polymer- or metal-layer based approaches. Here, we report shape changing films powered by DNA strand exchange reactions that have two different domains, which can respond to distinct chemical signals (Figure 1). The films are formed from DNA-grafted gold nanoparticles using a layer-by-layer deposition process. Films consisting of an active and a passive layer show rapid, reversible curling in response to stimulus DNA strands added to solution. Films consisting of two independently addressable active layers display a complex suite of repeatable transformations (Figure 2), involving eight mechano-chemical states and incorporating self-righting behavior.
Figure 1. Strand-exchange reactions enable reversible DNA-GNP swelling. Schematic (top) and detailed design (bottom) for reversible expansion and contraction of DNA-GNP film.
Figure 2. Dual addressable DNA-GNP films explore a two-dimensional configuration space. (a) Schematics for dual active DNA-GNP film composed of (AC)5(DC)5 where both AC and DC domains are active layer. (b) Series of microscope images for actuation of dual active DNA-GNP film. When the top AC layer (green) was contracted (top), contraction occurred throughout the entire surface of the layer which results in smooth curling to tubular structure. When the bottom DC layer (red) was contracted (bottom), periphery of the film was contracted first (mid-bottom) and then it curled downward to tubular structure.
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Tae Soup Shim, Zaki G. Estephan, Zhaoxia Qian, Jacob H. Prosser, Su Yeon Lee, David M. Chenoweth, Daeyeon Lee,* So-Jung Park,* John C. Crocker*, “Shape Changing Thin Films Powered by DNA Hybridization” Nature Nanotech., 2017, 12, 41–47