Dynamic Hydrogels from Host–Guest Supramolecular Interactions

Abstract

Hydrogel biomaterials are pervasive in biomedical use. Applications of these soft materials range from contact lenses to drug depots to scaffolds for transplanted cells. A subset of hydrogels is prepared from physical cross‐linking mediated by host–guest interactions. Host macrocycles, the most recognizable supramolecular motif, facilitate complex formation with an array of guests by inclusion in their portal. Commonly, an appended macrocycle forms a complex with appended guests on another polymer chain. The formation of poly(pseudo)rotaxanes is also demonstrated, wherein macrocycles are threaded by a polymer chain to give rise to physical cross‐linking by secondary non‐covalent interactions or polymer jamming. Host–guest supramolecular hydrogels lend themselves to a variety of applications resulting from their dynamic properties that arise from non‐covalent supramolecular interactions, as well as engineered responsiveness to external stimuli. These are thus an exciting new class of materials.

Supramolecular Hydrogels for Biomedical Applications

“…Next, Webber and colleagues review the area of supramolecular hydrogels prepared from macrocyclic host-guest motifs. [21] This contribution reviews the extensive body of work that has used the recognition between synthetic macrocyclic hosts and pendant hydrophobic guests to facilitate physical crosslinking of macromolecules, as well as efforts to induce hydrogelation by threading macrocycles with polymer strands to form poly(pseudo)rotaxanes. The many benefits that arise from the use of recognition of different synthetic motifs are described.…”

Structural considerations for physical hydrogels based on polymer–nanoparticle interactions

“…Supramolecular hydrogels have shown potential for applications in drug delivery, cell delivery, biomaterials, and 3D printing. [1][2][3][4][5][6][7][8][9][10] The utility of these materials is largely due to function-critical properties, such as injectability, self-healing, biodegradability, and biocompatibility, which are largely enabled by the transient physical interactions that crosslink the hydrogels. 8,9,[11][12][13][14][15] Moreover, the abundance of available physical interactions (e.g., host-guest, ionic, hydrogen bonding, peptide, and hydrophobic interactions) offers a broad chemical space to design new materials.…”

“…8,9,[11][12][13][14][15] Moreover, the abundance of available physical interactions (e.g., host-guest, ionic, hydrogen bonding, peptide, and hydrophobic interactions) offers a broad chemical space to design new materials. [6][7][8][16][17][18] Among these crosslinking motifs are polymernanoparticle (PNP) interactions, which consist of multivalent physical bonds between polymers and the surface of nanoparticles that imbue materials with complex flow behavior and enhanced elasticity. [19][20][21][22] These PNP interactions are highly modular and tunable, and provide a simple strategy for self-assembly without the need to design specific small-molecule binding partners.…”

Kinetic Evolution in Metal‐Dependent Self‐Assembly of Peptide–Terpyridine Conjugates

“…

As the engineering of materials has frequently looked to nature for inspiration, principles arising from supramolecular chemistry afford one logical means with which to include specific non-covalent interactions in designed functional materials. [14][15][16][17][18][19] Interesting properties and resulting functions are furthermore likely to result from the integration of multiple of these disparate supramolecular motifs into a single material. Accordingly, supramolecular materials have been created through diverse motifs designed at the molecular scale to include classes of self-assembling oligopeptides, host-guest recognition motifs, metal-ligand coordination complexes, and hydrogen bonding motifs, among many others.

…”

“…Accordingly, supramolecular materials have been created through diverse motifs designed at the molecular scale to include classes of self-assembling oligopeptides, host-guest recognition motifs, metal-ligand coordination complexes, and hydrogen bonding motifs, among many others. [14][15][16][17][18][19] Interesting properties and resulting functions are furthermore likely to result from the integration of multiple of these disparate supramolecular motifs into a single material. The many different supramolecular materials which have been explored have empowered new applications to address challenges in medicine, electronics, catalysis, industrial processes, environmental remediation, energy harvesting, and a variety of other uses.…”