Applications of guanine quartets in nanotechnology and chemical biology

Guanine and related nucleobases such as guanosine, deoxyguanosine and isoguanosine are notable molecular tools for designing functional supramolecular assemblies. This popularity originates in their ability to self-assemble via a unique topological pluralism — as isolated nucleobases, discrete macrocyclic quartets and virtually infinite linear ribbons — that endows them with a considerable functional versatility. Many programmes have been launched to fine-tune the chemical properties of guanine derivatives, to make them usable under different experimental conditions, such as in organic or aqueous environments, and responsive to external stimuli, such as ionic strength, pH, light or temperature. These strategies aim to translate the chemical information encoded in a basic guanine unit into programmable, higher-order supramolecular architectures. Spectacular results have been recently obtained in various chemical fields, from supramolecular chemistry to chemical biology, from soft matter to catalysis. In this Review, we detail these advances and demonstrate how these multidisciplinary investigations cast a bright light on the diversity that guanines, synthetic guanines and related nucleobases uniquely offer in terms of both structure and function. The propensity of guanine and its derivatives to assemble into guanine quartets makes them a privileged tool in the design of functional supramolecular assemblies. This Review describes the production of such functional suprastructures and their applications in nanotechnology, soft matter and chemical biology.