Design and operation of reconfigurable two-dimensional DNA molecular arrays.

Information relay and cascaded transformation are essential in biology and engineering. Imitation of such complex behaviors via synthetic molecular self-assembly at the nanoscale remains challenging. Here we describe the use of structural DNA nanotechnology to realize prescribed, multistep, long-range information relay and cascaded transformation in rationally designed molecular arrays. The engineered arrays provide a controlled platform for studying complex dynamic behaviors of molecular arrays and have a range of potential applications, such as with reconfigurable metamaterials. A reconfigurable array consists of a prescribed number of interconnected dynamic DNA antijunctions. Each antijunction unit consists of four DNA domains of equal length with four dynamic nicking points, which are capable of switching between two stable conformations through an intermediate open conformation. By interconnecting the small DNA antijunctions, one can build custom two-dimensional (2D) molecular 'domino' arrays with arbitrary shapes. More important, the DNA molecular arrays are capable of undergoing programmed, multistep, long-range transformation driven by information relay between neighboring antijunction units. The information relay is initiated by the trigger strands under high temperature or formamide concentration. The array's dynamic behavior can be regulated by external factors such as its shape and size, points of transformation initiation, and/or any engineered information propagation pathways. This protocol provides detailed strategies for designing DNA molecular arrays, as well as procedures for sample production, purification, reconfiguration, and imaging by atomic force microscopy (AFM) and transmission electron microscopy (TEM). The procedure can be completed in 4-7 d.