Controlling the self-assembly of amphiphiles using DNA G-quadruplexes

Abstract

Aside from its biological role, the DNA molecule is fascinating because of its unique self-assembly properties. Through selective recognition between complementary nucleobases, two antiparallel strands of DNA assemble into the well-known double helix structure. Thanks to these properties, DNA is an ideal template to construct functional nanomaterials with various applications. Interestingly, DNA containing repetitive sequences of nucleobases can self-associate into various secondary structures that differ from the canonical double-helix conformation. Specifically, guanosine nucleosides possess a unique structure that allows for the interaction of four residues via Hoogsteen H-bonds. The resulting planar tetramers (G-quartets) with their polarized aromatic surfaces can associate via π- π stacking interactions forming the G-quadruplex (G-4) secondary structures. The research described in this thesis aimed to explore the potential of supramolecular DNA G-4 based self-assemblies. Specifically, a tetramolecular parallel G-4 was employed as template to control the organization of amphiphilic molecules, such as lipids or peptides. G-rich oligonucleotides were covalently attached to the amphiphilic molecules, resulting in hybrid structures that combined the molecular recognition properties of DNA G-4s and the hydrophobic interactions typical of surfactants self-assembly. Moreover, the ability to trigger conformational changes in the G-4 structure in presence of metal ions, complementary strands or small molecules, was exploited to achieve novel DNA-based functional systems that can be controlled by external stimuli