Embedded 3D Printing of Graphene Oxide-Containing, Chemically Crosslinkable Poly(Ethylene Glycol) Inks

The incorporation of graphene-based materials into hydrogels enhances their mechanical, electroconductive, and antimicrobial properties, offering significant potential for biomedical applications. However, 3D printing graphene-containing inks may present challenges because of their unsuitable shape retention or the fact that the concentration of the graphene component can hinder photocrosslinking. This study explores embedded 3D printing to process a chemically crosslinkable poly(ethylene glycol) ink with a high (4% w/v) graphene oxide concentration (PEG/GO). Given the PEG/GO ink's insufficient shape retention and slow crosslinking, various support baths are screened, with the microparticulate bath of the crystal self-healing embedding bioprinting (CLADDING) method proving most effective. The interstitial solution of the CLADDING bath influences the mechanical properties of printed PEG/GO constructs. Multilayered PEG/GO cylindrical constructs with <500 μm filament width and up to 4.5 mm height (30 layers) are fabricated, presenting better tensile properties when printed within CLADDING in calcium chloride (vs. baths in crosslinking initiators). The surface of PEG/GO constructs is anti-adhesive toward human foreskin fibroblasts, and their extracts are cytocompatible. Hence, embedded 3D printing emerges as an innovative strategy to surpass limitations of shaping graphene-containing hydrogels into complex geometries, broadening the biomanufacturing possibilities for diverse biomedical applications requiring kPa-range mechanical properties.