A G₄·K⁺ Hydrogel Stabilized by an Anion

Abstract

Supramolecular hydrogels derived from natural products have promising applications in diagnostics, drug delivery, and tissue engineering. We studied the formation of a long-lived hydrogel made by mixing guanosine (G, 1) with 0.5 equiv of KB(OH)4. This ratio of borate anion to ligand is crucial for gelation as it links two molecules of 1, which facilitates cation-templated assembly of G4·K(+) quartets. The guanosine-borate (GB) hydrogel, which was characterized by cryogenic transmission electron microscopy and circular dichroism and (11)B magic-angle-spinning NMR spectroscopy, is stable in water that contains physiologically relevant concentrations of K(+). Furthermore, non-covalent interactions, such as electrostatics, π-stacking, and hydrogen bonding, enable the incorporation of a cationic dye and nucleosides into the GB hydrogel.

Structure and Distribution of Cross-Links in Boron-Modified Phenol–Formaldehyde Resins Designed for Soft Magnetic Composites: A Multiple-Quantum 11B–11B MAS NMR Correlation Spectroscopy Study

“…In the molecular models representing thermally converted PF resins the methylene (−O−CH 2 −) carbons are further substituted by amino groups. As reference compounds boric acid, borate anion (B(OH) 3 and B(OH) 4 − ) and the recently reported cyclic five-member guanosine−borate monoesters and guanosine−borate diesters 35,36 were employed in the DFT calculations (for optimized geometries of the reference compounds see Supporting Information). As graphically presented in Figure 6b, the 11 B NMR chemical shielding parameters calculated for all the reference compounds as well as for the proposed structural models nicely fit their experimental counterparts (i.e., the assigned 11 B NMR chemical shifts).…”

Redox‐Active Dynamic Self‐Supporting Thixotropic 3D‐Printable G‐Quadruplex Hydrogels

“…[33b, 34] TEM images of the gel(green) showed short and sparse fibres,o wing to the ionic nature of the ferrocenium;h owever, the gel (brown)e xhibited entangled G-quadruplex nanofibers with an averaged iameter of 20 nm and several micrometres in length ( Figure 4). [17,18] In gel (brown), an intense positive peak at 490 nm and an egative peak at 530 nm were attributed to supramolecular chirality generated by the ferrocenem oiety. [35,36] AC Ds tudy was performed with the gels.…”

“…[13] Underc ertain experimental conditions, these nanofibrous networks encapsulate enough water to produce gel-phase materials (G4 hydrogels).G -quadruplex structures are stabilised in the presence of metal ions, especially K + ions. [14][15][16][17][18] Recently,G 4h ydrogels have drawn great attraction for severala pplications in different fields. [14][15][16][17][18] Recently,G 4h ydrogels have drawn great attraction for severala pplications in different fields.…”

“…[17,21,22] Ferrocene-functionalised hydrogel can change its hydrophilicity and hydrophobicity by changing the oxidation state of the Fe centre. Boronate ester mediated LMW G4 hydrogels are dynamic, self-healablea nd thixotropic in nature owing to the dynamic behaviour of the boronic acid-boronate ester equilibrium in aqueous medium.…”

Controlled supramolecular structure of guanosine monophosphate in the interlayer space of layered double hydroxide

“…They suggested those supramolecular nucleoside structures could be utilized for molecular nanowire fabrication or molecular electronics. Davis et al prepared stable G4 hydrogels utilizing guanosine, potassium and borate [9]. Those hydrogels exhibited specific binding ability towards cationic dyes or nucleoside through noncovalent interactions.…”