α-Cyclodextrin-Based Polypseudorotaxane Hydrogels

Abstract

Supramolecular hydrogels that are based on inclusion complexes between α-cyclodextrin and (co)polymers have gained significant attention over the last decade. They are formed via dynamic noncovalent bonds, such as host-guest interactions and hydrogen bonds, between various building blocks. In contrast to typical chemical crosslinking (covalent linkages), supramolecular crosslinking is a type of physical interaction that is characterized by great flexibility and it can be used with ease to create a variety of "smart" hydrogels. Supramolecular hydrogels based on the self-assembly of polypseudorotaxanes formed by a polymer chain "guest" and α-cyclodextrin "host" are promising materials for a wide range of applications. α-cyclodextrin-based polypseudorotaxane hydrogels are an attractive platform for engineering novel functional materials due to their excellent biocompatibility, thixotropic nature, and reversible and stimuli-responsiveness properties. The aim of this review is to provide an overview of the current progress in the chemistry and methods of designing and creating α-cyclodextrin-based supramolecular polypseudorotaxane hydrogels. In the described systems, the guests are (co)polymer chains with various architectures or polymeric nanoparticles. The potential applications of such supramolecular hydrogels are also described.

Current Progress in Cross-Linked Peptide Self-Assemblies

“…A typical change is hydrogelation, which enables the design of attractive biomaterials, including cell culture scaffolds. Conventionally, the effects of cross-linking have been investigated using covalent polymers [ 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 ]. Mechanically robust nanocomposite hydrogels can be prepared by the use of clay nanosheets at cross-linking points [ 68 , 69 ].…”

“…When the double network hydrogels are damaged, the first polymer network absorbs the impact energy and prevents breakage of the second polymer network. Slide-ring hydrogels composed of polyethylene glycol (PEG)-based networks where two connected cyclodextrins are utilized as cross-linking points are known to exhibit extremely high stretchability [ 75 ]. Since PEG can move though the cavity of cyclodextrins, cross-linking points of PEG–cyclodextrin complexes rearrange to soften the impact force on cross-linking points, preventing fracture of the hydrogels.…”

“…A representative example is hydrogelation, which converts peptide fiber dispersions into self-standing materials for biomaterial applications including cell culture scaffolds. Cross-linking methods, which have been extensively developed using covalent water-soluble polymers [ 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 ], are also effective in the cases of supramolecular peptide fibers. In particular, unique cross-linking methods can be employed by taking advantage of the functionalities of amino acid residues in peptide fibers [ 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 88 , 89 , 90 ].…”

Design of Bio-Conjugated Hydrogels for Regenerative Medicine Applications: From Polymer Scaffold to Biomolecule Choice

“…Macrocyclic oligosaccharides have an internal hydrophobic pocket with which hydrophobic drugs can associate. In those systems, the drug release is primarily controlled by the relative partitioning of solubilized drugs between the hydrogel and the release medium, and is independent of the mesh size of the hydrogel [ 192 , 193 ]. The high selectivity due to molecular recognition is a major advantage of host-guest interactions.…”

Stimuli-Responsive Aliphatic Polycarbonate Nanocarriers for Tumor-Targeted Drug Delivery

“…However, the non-biodegradability of PEG is the main obstacle to in vivo application. In addition, the use of PEG with a molar mass higher than 10,000 Da is problematic, as it cannot be filtered out by the human kidneys due to its large hydrodynamic radius [46]. Therefore, non-biodegradable PEGylated copolymers and free PEG accumulate in the liver with unspecified toxicological consequences [47].…”