Dynamically crosslinked materials via recognition of amino acids by cucurbit[8]uril

Hydrogels, an increasingly important class of material, have physical properties amenable to many potential uses, particularly in the biomedical area. Utilisation of hydrogels, however, relies not only on their mechanical properties but also on a favourable toxicity profile. Self assembly of polymers through naturally occurring and non-toxic units is therefore a very attractive option. The aromatic amino acids phenylalanine and tryptophan are two such molecular units that form 2 : 1 complexes with cucurbit[8]uril (CB[8]) with high binding equilibrium constants (K_eq up to 10¹² M^-2). Herein, water soluble styrenic monomers were copolymerised with synthetically derived aromatic amino acid monomers of phenylalanine and tryptophan. The resulting polymers were shown to form dynamic and self-healing physically crosslinked hydrogels via recognition and binding of the amino acids to cucurbit[8]uril.