Reversible Reconfiguration of High-Order DNA Nanostructures by Employing G-quartet Toeholds as Adhesive Units

G-quadruplex structures are becoming useful alternative interaction modules for the assembly of DNA nanomaterials because of their unique inducibility by cations. In this study, we demonstrated a new strategy for the assembly of polymeric DNA nanoarchitectures in the presence of cations such as K+ and Na+, by employing G-quartet toeholds at the edges of discrete mini-square DNA building blocks as adhesive units. In comparison to the the Watson-Crick base-paired duplex linkers, G-quadruplex array embedded in the self-assembled DNA system exhibit hiigher thermal stability. The morphology of these DNA nanostructures in doughnut-shaped or spherical-shaped is highly regulated by the orientation of the folded G-quadruplexes either in parallel and/or antiparallel orientation in response to different cations. Furthermore, this G-quadruplex-mediated assembly strategy is able to manipulate the DNA assemblies cycling between discrete and polymeric states by means of introducing cations and chelating agent sequentially. This property enables the reversible manipulation of the DNA-based nanosystem for at least 4 cycles. The G-quadruplex array embedded in this self-assembled DNA system can become a scaffold for functional molecules as a number of organic molecules and proteins exhibit specific binding to these G-quadruplex structures. Besides, embedded G-quadruplexes also considered as functional components of nanoscale electronic materials due to electron transport through the stacked orientation of the G-quartet. Therefore, this work is an important step toward in obtaining reversible, responsive G-quadruplex-induced DNA-based nanomaterials with versatile functionalities which will be highly useful for further electronic, biomedical and drug-delivery applications.