We report the effect of chemical and physical treatments on the structural stability of DNA origami nanostructures. Our result shows that DNA nanostructure maintains its shape under harsh processing conditions, including thermal annealing up to 200°C for 10 min, immersing in a wide range of organic solvents for up to 24 h, brief exposure to alkaline aqueous solutions, and 5 min exposure to UV/ O 3 . Our result suggests that the application window of DNA nanostructure is significantly wider than previously believed.
■ INTRODUCTIONThe past decade has witnessed an explosive growth in the design and synthesis of DNA nanostructures. Through careful design of sequences, almost any desired 2D and 3D shapes can be constructed with nanometer scale precision and accuracy. Examples of such structures include individual 2D and 3D objects, 1−6 1D nanowires and nanotubes, 7,8 2D lattices, 9 and 3D crystals. 10 Many of the applications of DNA nanostructures take advantage of their precise and highly configurable geometries. DNA nanostructures have been used as templates to pattern and direct the assembly of various biomolecular, organic, and inorganic materials, including metal nanoparticles, 8,11−19 proteins, 11,12,20,21 carbon nanotubes, 22,23 and quantum dots. 24 In addition, efforts have also been made to use DNA as a template to directly or indirectly pattern graphene and inorganic oxide substrates. 25−29 For example, Becerril et al. used aligned DNA molecule as a shadow mask for angled metal vapor deposition. 25 A spatial resolution in the sub-10 nm range was demonstrated. Deng et al. reported the metal evaporation onto DNA nanostructures deposited on a mica substrate followed by lift-off to create metal replicas of DNA. 26 Recently we demonstrated the use of DNA nanostructures as a mask for the etching of SiO 2 and chemical vapor deposition of inorganic oxides; in both cases, both positive tone and negative tone pattern transfers were obtained through a careful control of the reaction conditions. 28,29 Although significant progress has been made, using DNA nanostructures in the bottom-up fabrication still faces significant challenges. In particular, many bottom-up fabrications involve very harsh processing conditions such as high temperatures and corrosive chemicals. However, DNA is a soft, chemically labile material that has limited thermal and chemical stability. In fact, even widely used solution phase processes could pose a significant risk, since deposited DNA nanostructures could be easily lifted-off from the substrate. 13,17 Because of this reason, the success of a DNA-mediated bottom-up fabrication is often limited and constrained by the stability of DNA nanostructures themselves. Therefore, understanding their structural stability under various chemical and physical environments is critical to the advance of this field of research.In aqueous solution, the kinetics and thermodynamics of DNA hybridization are well understood. Several groups have recently investigated the stability of DNA nanostructure in buff...
