Printing fragile cells into 3D objects that organize themselves into functional tissues with dimensions similar to human organs remains an enormous challenge. The group of PI Lütolf has shown that it is possible to grow functional centimeter-sized intestinal tissues by printing organoid-forming stem cells directly into naturally derived extracellular matrices (ECMs) such as Matrigel or collagens. This study demonstrated the potential of organoid-based bioprinting to recapitulate multicellular self-organization at the macroscopic level. However, due to the fast and uncontrollable cross-linking of the native ECMs, this approach only allows short-term printing at low temperatures. There is therefore a need for novel synthetic biomaterials that enable stable, long-term bioprinting at room temperature. The group of PI Amstad has developed viscoelastic capsules composed of functional block-copolymer based surfactants that are ionically crosslinked at the drop surface. The viscoelastic capsules are biocompatible and sufficiently robust to remain intact during the 3D printing process, but can be re-shaped when sufficiently strained thanks to their viscoelastic behavior. These capsules have thus the potential to enable the next generation 3D printing of functional organoids, which is the goal of this project.