Embedded 3D Printing of Cryogel-Based Scaffolds

Cryogel-based scaffoldshave attracted great attention in tissueengineering due to their interconnected macroporous structures. However,three-dimensional (3D) printing of cryogels with a high degree ofprecision and complexity is a challenge, since the synthesis of cryogelsoccurs under cryogenic conditions. In this study, we demonstratedthe fabrication of cryogel-based scaffolds for the first time by usingan embedded printing technique. A photo-cross-linkable gelatin methacryloyl(GelMA)-based ink composition, including alginate and photoinitiator,was printed into a nanoclay-based support bath. The layer-by-layerextruded ink was held in complex and overhanging structures with thehelp of pre-cross-linking of alginate with Ca2+ presentin the support bath. The printed 3D structures in the support bathwere frozen, and then GelMA was cross-linked at a subzero temperatureunder UV light. The printed and cross-linked structures were successfullyrecovered from the support bath with an integrated shape complexity.SEM images showed the formation of a 3D printed scaffold where porousGelMA cryogel was integrated between the cross-linked alginate hydrogels.In addition, they showed excellent shape recovery under uniaxial compressioncycles of up to 80% strain. In vitro studies showedthat the human fibroblast cells attached to the 3D printed scaffoldand displayed spread morphology with a high proliferation rate. Theresults revealed that the embedded 3D printing technique enables thefabrication of cytocompatible cryogel based scaffolds with desiredmorphology and mechanical behavior using photo-cross-linkable bioinkcomposition. The properties of the cryogels can be modified by varyingthe GelMA concentration, whereby various shapes of scaffolds can befabricated to meet the specific requirements of tissue engineeringapplications.