Controlled gelation kinetics of cucurbit[7]uril-adamantane cross-linked supramolecular hydrogels with competing guest molecules

Abstract

Gelation kinetics of hydrogels is closely linked to many applications such as the development of injectable and printable hydrogels. However, the control of gelation kinetics without compromising the structure and other properties of the hydrogels, remains a challenge. Here, we demonstrate a method to control the gelation kinetics of cucurbit[7]uril-adamantane (CB[7]-AD) cross-linked supramolecular hydrogels by using competing guest molecules. The association between CB[7] and AD moieties on the polymer backbone was impeded by pre-occupying the CB[7] cavity with competing guest molecules. By using various guest molecules and concentrations, the gelation of the hydrogels could be varied from seconds to hours. The strong interaction of CB[7]-AD pair endue the hydrogels good mechanical properties and stability. Moreover, the binding of functionalized guest molecules of CB[7] moieties offers a facile approach for tailoring of the hydrogels’ scaffold. Combined with hydrogel injection and printing technology, this method offers an approach for the development of hydrogels with advanced temporal and spatial complexity.

Hydrogel and Organogel Formation by Hierarchical Self‐Assembly of Cyclic Peptides Nanotubes

“…The absence of a cross point of the G ′ and G ′′ at high strain, as commonly observed amongst other supramolecular hydrogels, indicates that the hydrogel is stable up until 100 % strain, which may be attributed to the highly dynamic nature of these self‐assembled systems . This is in accordance with previous observations in the literature where similar systems showed a decrease in the elastic modulus only at strains higher than 100 % . Taken together, the results suggest that, despite minor differences in the storage modulus of hydrogels made from CP 5 , CP 7 and CP 11 , all three hydrogels show very similar rheological behaviour.…”

Recent advances in shear‐thinning and self‐healing hydrogels for biomedical applications

“…Cucurbit[n]uril ( n = 5–8, 10; CB[ n ]) is a symmetrical macromolecule that can form a complex with an ammonium ion with exceptionally high binding affinity and selectivity in aqueous solution . The cavity size of CB[ n ] and the length of the guest molecule for hydrophobic interaction and hydrogen bonding are important factors for the formation of a CB–guest complex . In contrast to the smaller CB[ n ] homologues, CB[8] has a larger cavity volume (479 Å) capable of simultaneously accommodating two planar and hydrophobic guests in a π−π‐stacked geometry .…”

Dynamic Hydrogels from Host–Guest Supramolecular Interactions

“…This same hydrogel material demonstrated controlled chondrogenesis of encapsulated mesenchymal stem cells ( Figure 3 A), as well as the long‐term encapsulation and support of mesenchymal stem cells engineered to produce mutant interleukin‐12 to suppress the growth of nearby tumors . Though most work on this class of macrocycles has focused on CB[6], the more water‐soluble CB[7] has also been used along with an adamantane guest installed pendant on polymers, forming a gel when the two components were mixed . In this work, the gelation kinetics could be varied by first occupying the CB[7] portal with a competing monomeric guest, resulting in gels that formed instantly, within minutes, or over the course of hours depending on affinity of the competing guest.…”