Cu(I)-Induced G-Quartets: Robust Supramolecular Polymers Exhibiting Heating-Induced Aqueous Phase Transitions Into...

Area of Science:

• Supramolecular Chemistry
• Biomaterials Science
• Nanotechnology

Background:

• Proteins and synthetic polymers exhibit aqueous phase transitions for self-assembly.
• Guanosine can form G-quartets, a non-canonical DNA secondary structure, often stabilized by potassium ions (K+).

Purpose of the Study:

• To investigate the self-assembly and phase transition behavior of supramolecular polymers (SPs) formed by guanosine and copper(I) (Cu+).
• To explore the potential of Cu+-induced G-quadruplexes for creating novel functional materials.

Main Methods:

• Formation of G4.Cu+ supramolecular polymers in aqueous solution.
• Characterization of self-assembly through π-π stacking, metallophilic, and hydrophobic interactions.
• Computational analysis of interaction energies.
• Observation of heating-induced phase transitions and hydrogel formation.
• Exploitation of Cu+/Cu2+ redox reversibility for controlled assembly/disassembly.

Main Results:

• Guiding by Cu+, guanosine formed a highly stable G-quartet (G4.Cu+) G-quadruplex with temperature tolerance, distinct from G4.K+.
• G4.Cu+ SPs demonstrated enhanced thermal stability due to strong Cu+ coordination and metallophilic interactions.
• Aqueous G4.Cu+ SP solutions exhibited lower critical solution temperature (LCST) behavior, forming hydrogels below the cloud point and precipitates above it.
• The LCST behavior originated from biomolecular functionality, not typical thermo-responsive groups.
• Redox cycling of Cu+/Cu2+ allowed reversible control over G-quadruplex assembly and gelation.

Conclusions:

• Cu+-induced G-quadruplexes form thermally robust supramolecular polymers with unique LCST behavior.
• This system offers a novel biomolecular approach to stimuli-responsive hydrogel formation and material control.
• The findings open avenues for developing advanced self-assembling materials with tunable properties.