Regulation of Non-canonical DNA Structures by Small Molecules and Carbon Materials
DNA can form non-canonical structures under certain conditions, such as Z-DNA, A-motif, G-quadruplex, i-motif, triplex, hairpin, and cruciform. These structures are particularly seen in the human genome with repeat DNA sequences, and some of them have been proposed to participate in several biologically important processes, including gene regulation, expression, and evolution, and thus could be potential drug targets. The structures and physicochemical properties of non-canonical DNA are closely related to their biological functions. Due to their unique three-dimensional structures, small molecules can stabilize or alter their structures, and are thus possible able to regulate their biological functions. Small molecules that can regulate five typical non-canonical DNA structures are reviewed. In addition to small molecules, carbon materials, such as carbon nanotubes (CNTs) and graphene oxides (GO), exhibited super ability at tuning the structures of typical helical DNA and non-canonical DNA structures due to their unique structural and chemical physical properties. Recent progress with these two types of materials in regulating DNA structures is described. Particular focus is given to the applications of CNTs and GO in gene delivery and as anticancer drugs. Finally, the perspectives related to the applications of CNTs and GO in these fields are highlighted.