DNA Based Dual-Spring Cross Shaped Nanoactuator

Abstract

DNA is an attractive platform for nanotechnology applications because of its size, specificity, and designability. However constructing DNA-based platforms that can do work is difficult. We have developed a DNA-based cross-shaped nanoactuator system that cycles between an extended and contracted confirmation relying on strand displacement reactions. The actuator contains 4 structural strands with two unique DNA “zipper” sequences. Each zipper sequence employs traditional adenosine-thymine nucleotides as well as non-traditional inosine-cytidine nucleotides. The I-C bond consists of only 2 hydrogen bonds as opposed to the typical 3 hydrogen bonds found in G-C bonds. The actuator is extended by inserting two ssDNA which are the natural complements to the zipper sequences. The natural complements have a stronger binding affinity to one side of the zipper than both zipper strands have to each other, thus unraveling and allowing the actuator to extend. The two contraction strands contain sequences which are a natural complement to parts of the opening strand. When they bind to the extension sequences, the zippers are able to rebind and this contracts the actuator. Proper assembly and function of the devices was confirmed using fluorescent DNA gel electrophoresis, AFM imaging, and time-lapsed fluorescence.