Cryogels are 3D sponge-like networks with interconnected macropores. Their unique properties make cryogels attractive for numerous biomedical applications, especially as scaffolds for tissue engineering, drug carriers or wound healing devices. Cryogelation is an effective, low-cost process occurring in aqueous media only requiring cross-linkable functionalities within the starting materials.
Due to their excellent biocompatibility combined with potential biodegradability, biopolymeric cryogels based on polysaccharides like dextran, chitosan hyaluronan, or proteins like collagen or gelatine are promising starting materials. In addition the polyfunctionality of those biopolymers allows a large variety of derivatization to initiate cross-linking reactions. The combination of biopolymers with stabilizing synthetic macromers can influence the cryogel properties and therefore extend their application potential.
Various cryogels based on modified or unmodified biomaterials as well as on commercially available synthetic precursors/macromers have been successfully produced. Different cross-linking agents, like photo-initiators or dialdehydes have been applied and the cryogel compared also to other cross-linking techniques using high energy irradiation. Among the studied cross-linkable components, the synthetic macromonomer polyethylene glycol diacrylate (PEGDA) has been found to provide biopolymer cryogels with excellent mechanical stability, inter-connecting porosity and an encouraging in vitro cytocompatibility. Furthermore, the addition of small quantities of egg shell membrane protein particles to the cryogel starting mixtures, considerably increases the ability of cells to adhere onto the cryogel surfaces or even migrate into the porous structure. Overall, cryogels based on mixtures of biomaterials and synthetic cross-linkable macromers or precursors are promising candidates for wound dressings support tissue regeneration.