Metal-mediated DNA strand displacement and molecular device operations based on base-pair switching of 5-hydroxyuracil nucleobases

Rational design of self-assembled DNA nanostructures has become one of the fastest-growing research areas in molecular science. Particular attention is focused on the development of dynamic DNA nanodevices whose configuration and function are regulated by specific chemical inputs. Herein, we demonstrate the concept of metal-mediated base-pair switching to induce inter- and intramolecular DNA strand displacement in a metal-responsive manner. The 5-hydroxyuracil (U(OH)) nucleobase is employed as a metal-responsive unit, forming both a hydrogen-bonded U(OH)–A base pair and a metal-mediated U(OH)–Gd(III)–U(OH) base pair. Metal-mediated strand displacement reactions are demonstrated under isothermal conditions based on the base-pair switching between U(OH)–A and U(OH)–Gd(III)–U(OH). Furthermore, metal-responsive DNA tweezers and allosteric DNAzymes are developed as typical models for DNA nanodevices simply by incorporating U(OH) bases into the sequence. The metal-mediated base-pair switching will become a versatile strategy for constructing stimuli-responsive DNA nanostructures, expanding the scope of dynamic DNA nanotechnology.