Self-standing gelatin- methacryloyl 3D structure using Carbopol-embedded printing

Gelatin-methacryloyl (GelMA) hydrogel has gained huge success in the lastdecades thanks to its versatilities in many applications. Notably, one of them is3D bioprinting, as GelMA physical-mechanical properties and biocompatibilityof uncured formulation perfectly suit the requirements of a bioink. Neverthe-less, before the photopolymerization, the hydrogel shows weak mechanicalproperties and long recovery time after stress application, which results in theinability to obtain complex and self-standing forms due to structure collapse.In this work, Carbopol ETD 2020 NF, dissolved in cell culture medium, wasused as supporting bath to optimize GelMA bioprinting and overcome its sta-bility limitations. The achieved results demonstrated the possibility of printingshapes containing hollows with lumens or non-planar surfaces, also by usingnozzles with larger inner diameter, which reduced cell death during printingprocess, but were usually avoid because of low resolution. Moreover, con-structs' extraction was easier when Carbopol solution was prepared in culturemedium rather than in water, reducing sample handling. In conclusion,thanks to this supporting bath, it was possible to print cellularized scaffold,with channels that were then seeded, obtaining inner structure. Further, thisCarbopol formulation could be considered an eligible candidate as a support-ing bath to obtain GelMA 3D self-standing-shaped and vascularized scaffold.