A G₄·K⁺ hydrogel stabilized by an anion

Area of Science:

• Supramolecular chemistry
• Materials science
• Biomaterials

Background:

• Supramolecular hydrogels from natural products offer potential in diagnostics, drug delivery, and tissue engineering.
• Controlling hydrogel formation and stability is key for practical applications.

Purpose of the Study:

• To investigate the formation of a stable, long-lived supramolecular hydrogel using guanosine and borate.
• To characterize the structure and properties of the resulting guanosine-borate (GB) hydrogel.
• To explore the potential of the GB hydrogel for incorporating other molecules.

Main Methods:

• Mixing guanosine (G) with potassium borate (KB(OH)4) at a specific molar ratio (0.5 equiv).
• Characterization using cryogenic transmission electron microscopy (cryo-TEM), circular dichroism (CD), and (11)B magic-angle-spinning NMR spectroscopy.
• Assessing hydrogel stability in aqueous solutions with physiologically relevant potassium ion (K+) concentrations.
• Investigating the incorporation of a cationic dye and nucleosides via non-covalent interactions.

Main Results:

• A stable, long-lived guanosine-borate (GB) hydrogel was successfully formed.
• The specific ratio of borate to guanosine is critical for templating guanosine tetrads (G4·K+) and enabling gelation.
• The GB hydrogel demonstrated stability in the presence of physiologically relevant K+ concentrations.
• Non-covalent interactions allowed for the successful incorporation of a cationic dye and nucleosides into the hydrogel matrix.

Conclusions:

• The study successfully developed a novel guanosine-borate supramolecular hydrogel.
• The GB hydrogel exhibits excellent stability and the ability to encapsulate other molecules, highlighting its potential for advanced applications.
• This work provides a foundation for designing functional hydrogels based on nucleosides and borate chemistry.