G-quadruplex assemblies

Fig. 10.12 (A) The cation-templated hierarchic self-assembly of guanine alkoxysilane gives the C-quartet and (B) the G-quadruplex transcribed in solid hybrid materials by the sol-gel process.

Han H, Cliff CL, Hurley LH (1999) Accelerated assembly of G-quadruplex structures by a small molecule. Biochemistry 38 6981-6986... 

Davis, J. T. Lipophilic G-quadruplexes are self-assembled ion pair receptors, and the bound anion modulates the kinetic stability of these complexes. J Am Chem Soc 2003, 125, 10830-10841. 

Whitney, A. M. Ladame, S. Balasubramanian, S. Templated ligand assembly by using G-quadruplex DNA and dynamic covalent chemistry. Angew. Chem. Int. Ed. 2004,43, 1143-1146. 

The formation of aptamer-substrate complexes was also followed by the use of redox-active intercalators73 (Fig. 12.18d). A nucleic acid hairpin structure that contained in its single-stranded loop the antithrombin base sequence was assembled on a Au electrode, and methylene blue was intercalated as a redox label in the double-stranded stem of the hairpin structure. The hairpin was, then, opened in the presence of thrombin, by generating the respective G-quadruplex-thrombin complex, and as a result, the redox label was removed from the nucleic structure, showing a decrease in the voltammetric response with the increase in the concentration of thrombin. This method enabled the analysis of thrombin with a detection limit that corresponded to... 

Fig. 16 A Self assembling of G-quadruplex chiral aggregates and their stacking by interposition of cations. B Stereospecific binding of Ba2+ cations to give homochiral G-quadruplex, while K+ leads to heterochiral aggregates...

On the other hand, the G-quadruplex with a twisted supra molecular architecture represents a nice example of a dynamic chiral supramolecular system, when guanine and guanosine molecules are used. Molecular chirality may be used as a tool to assemble molecules and macromolecules into supramolecular structures with dissymmetric shapes. The supramolecular chirality, which results from both the properties and the way in which the molecular components associate, is by constitution dynamic and therefore examples of large-scale transcription of such virtual chirality remain rare. 

For all these reasons, the guanine building blocks and the sol-gel chemistry were used as molecular precursor to conceive hybrid chiral materials at nanometric and micrometric scales. Our efforts involved the synthesis and the self-assembly of a guaninesiloxane monomer Gsi (Fig. 3) in the G-quartet and G-quadruplex supramolecular architectures (Fig. 6), which are fixed in a hybrid organic-inorganic material by using a sol-gel transcription process, followed by a second inorganic transcription in silica, by calcination. 

Some systems can be applied in the areas of ionic, electron, and energy transport studies (9) and in sensing technology. Finally, our results show a new way of embedding nucleobases self-assembly and supramolecular chirality of G-quadruplexes in hybrid materials, of interest for the development of a supramolecular approach to nanoscience (51). Likewise, the hybrid polymeric arrays with nucleobases functionalities represent an area where the best is surely best to came it unlocks the door to the new materials world paralleling that of biology. 

A perylene derivative called PIPER was the first example of a small ligand behaving as a driver in the assembly of quadruplex structures.Gel-shift experiments demonstrate that PIPER can dramatically accelerate the association of a DNA oligomer containing two tandem repeats of the human telomeric sequence (TTAG3) into di- and tetrameric G-quadruplexes. In... 

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