GMP-quadruplex-based hydrogels stabilized by lanthanide ions

This work describes the gelation behaviors and properties of a biological molecule, guanosine 5′-monophosphate disodium salt (GMP), in the presence of trivalent lanthanide ions. Hydrogels composed of GMP-quadruplexes were prepared by adjusting pH, through which the protonation of phosphate group was controlled to tune the interactions between lanthanide ions and GMP. Within the pH region of 2–6, the electrostatic interaction between lanthanide ions and phosphate group is hindered and the cation-dipole interaction acts as the main driving force for the formation of G-quadruplexes. All the hydrogels were found consisting of three-dimensional network of the intertwining one-dimensional nanofibers formed by the stacking G-quartets induced by lanthanide ions. A significant fluorescence enhancement of thioflavin T (ThT), a fluorescent molecule, was found to be triggered by the G-quadruplex structures, for which the rotation of chromophoric groups on ThT molecules were prohibited due to the implant into the G-quadruplex structures.