Bottom-up design of bioinks as a tool to overcome current challenges in bioprinting

3D bioprinting combines biology, bioengineering, computer and materials science to develop complex constructs for different applications, such as tissue engineering, in vitro tissue modelling, contributing to personalized medicine approaches. One of  its  key ingredients is the bioink, which is a cells, biomaterials and biomolecules mixture extruded, layer-by-layer, into a 3D construct. This lecture will focus on the engineering principles underpinning bioink design and on recently emerged strategies for their development. The main requirements of bioinks will be initially introduced; then, the most widely investigated bioinks for 3D bioprinting will be described, focusing on their pros and cons and the available crosslinking methods for the stabilization of printed constructs. Finally, an in-depth analysis of the available tools for bioink characterization (e.g., rheology, printability testing) will be provided, together with a series of recently published high quality case studies