Construction of nanostructures based on quadruplex DNA scaffolds

Abstract

<p indent=0mm>DNA molecule served as the major carrier of genetic information has been proved to be an excellent assembly material in the construction of nanoscale structures. Over the past thirty years, various assembly methods of DNA nanomaterials have been established, including self-assembly of DNA tiles, DNA origami and other DNA nanotechnologies, based on specific complementary AT and GC base pairs. It is interesting to note that, in addition to traditional double helix structures, DNA molecules can also form other structures like triplex and quadruplex structures. Recently, people pay more attention to the study of quadruplex structures, including G-quadruplexes and I-motifs formed by G-rich and C-rich strands, respectively. It is because that quadruplex structures not only play significant roles in the regulatory regions of genes, but also can be programmed to construct DNA nanostructures due to their structural diversity and controllability during assembly. Here, this article mainly introduces the developments of DNA nanostructures assembled by quadruplex structures and describes their structural functionalities. First of all, the fabrications of DNA supramolecules formed by long telomeric sequences, short G-rich DNA strands and G-repeat-containing DNA strands are retrospected, which can assemble to be higher-ordered multimeric G-quad- ruplexes, G-wires, and G-quadruplex-linked DNA nanostructures, respectively. These assembled G-quadruplex nanostructures have potential to enhance the catalytic activity of G4/Hemin DNAzyme and act as a better candidate for conductive molecular nanowires. Subsequently, the DNA nanostructures assembled from long C-rich strands, short C-rich strands, C-repeat-containing strands and DNA sequences containing both G-repeat and C-repeat fragments are also discussed, which can form I-motif nanospheres, I-wires, I-motif-linked DNA nanostructures and quadruplex nanostructures, respectively. The pH-sensitivity of I-motifs can be used to construct DNA molecular machine, and map spatial and temporal pH changes in living systems, etc. From these results, we can conclude that the constructions of DNA nanostructures based on the self-assembly of DNA tiles or DNA origami have characteristics of mature technology and fine-structure mapping, which are also high cost and complexity of design; in comparison, these quadruplex-directed DNA nanostructures are relatively crude, which have advantages of low cost, structural controllability and simplicity in design. The combination of self-assembly of quadruplex scaffolds and DNA nanotechnology based on complementary base pairs may promote the wide applications of DNA nanomaterials in various areas.