Embedded 3D Printing of Cryogel-Based Scaffolds

Abstract

Cryogel-based scaffolds have attracted great attention in tissue engineering due to their interconnected macroporous structures. However, three-dimensional (3D) printing of cryogels with a high degree of precision and complexity is a challenge, since the synthesis of cryogels occurs under cryogenic conditions. In this study, we demonstrated the fabrication of cryogel-based scaffolds for the first time by using an 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-layer extruded ink was held in complex and overhanging structures with the help of pre-cross-linking of alginate with Ca 2+ present in the support bath. The printed 3D structures in the support bath were frozen, and then GelMA was cross-linked at a subzero temperature under UV light. The printed and cross-linked structures were successfully recovered from the support bath with an integrated shape complexity. SEM images showed the formation of a 3D printed scaffold where porous GelMA cryogel was integrated between the cross-linked alginate hydrogels. In addition, they showed excellent shape recovery under uniaxial compression cycles of up to 80% strain. In vitro studies showed that the human fibroblast cells attached to the 3D printed scaffold and displayed spread morphology with a high proliferation rate. The results revealed that the embedded 3D printing technique enables the fabrication of cytocompatible cryogel based scaffolds with desired morphology and mechanical behavior using photo-cross-linkable bioink composition. The properties of the cryogels can be modified by varying the GelMA concentration, whereby various shapes of scaffolds can be fabricated to meet the specific requirements of tissue engineering applications.

Nanoparticle‐Based Cryogels from Colloidal Aqueous Dispersion: Synthesis, Properties and Applications

“…As well, in the case of the 3D printing of a chitosan cryogel, the authors used polyurethane nanoparticles as crosslinker at 4 °C during 4 h to obtain what they called a “pre‐cryogel” and then it was extruded and deposited onto the printing platform at freezing temperatures (−20 °C) [105] . As well, in this work [106] , the authors created cryogel‐based scaffolds out of gelatin by using an embedded 3D printing method for tissue engineering application. This method involves the gelation of the printed 3D structure at subzero temperatures under UV light.…”

In-Bath 3D Printing of Anisotropic Shape-Memory Cryogels Functionalized with Bone-Bioactive Nanoparticles

“…However, none has combined 3D freeform printing with directional freezing or fully explored the formulation of nanocomposite cryogel precursor inks for fabricating nanoparticle-doped cryogel constructs. In this sense, freeform 3D printing has emerged as a widely used technique for fabricating constructs with spatially defined architectures. , Optimizing the fabrication of cryogels using this technique unlocks the design of complex cryogels with gravity-defying spatial arrangements.…”

Redox-Responsive “Catch and Release” Cryogels: A Versatile Platform for Capture and Release of Proteins and Cells

“…Moreover, the porosity of cryogel could affect in vitro cell adhesion, migration, and proliferation. 8,19,20 For example, Koc and co-workers reported that the porous composition of the prepared gelatin methacrylate-based cryogel scaffold enabled cell migration and adhesion due to its porous structure. 8 Over the past decades, a variety of efficient chemical transformations such as click-based reactions have been used to functionalize hydrogels, cryogels, and hydrogel coatings, but most such reactions are not capable of undergoing reversible attachment in a specific manner under mild conditions.…”

“…8,19,20 For example, Koc and co-workers reported that the porous composition of the prepared gelatin methacrylate-based cryogel scaffold enabled cell migration and adhesion due to its porous structure. 8 Over the past decades, a variety of efficient chemical transformations such as click-based reactions have been used to functionalize hydrogels, cryogels, and hydrogel coatings, but most such reactions are not capable of undergoing reversible attachment in a specific manner under mild conditions. 21−23 For example, while functionalization of polymeric scaffolds using the Diels−Alder reaction proceeds under ambient conditions, 24,25 release.…”