Development and assessment of bio-inspired granular hydrogels for 3D printing

The project is focused on the development of bio-inspired granular hydrogel inks for 3D printing starting from water in oil emulsions as templates. Among the countless organisms there is one that has attracted a lot of attention in the last decade, it is the marine mussel. Mussels secrete specialized proteins containing a high content of the catecholic amino acid 3,4-dihydroxyphenylalaine (DOPA), which provides the characteristic ability to grab onto wet surfaces. Mimicking the mussel byssus mechanism has been the main design criteria for the present work as well as other marine organisms such as sandcastle worms that exploit supramolecular interactions. The formulation is developed starting from the synthesis of the mussel-inspired microgels and assessing the rheological parameters that influence the printability as well as the chemical composition through Raman spectroscopy. The microgels are polymerized through photo-induced free radical polymerization and functionalized after synthesis with grafting of catecholic ligands, able to coordinate iron ions. By exposing the jammed microgels to a second polymeric network a dynamic glue based on electrostatic interactions is introduced, mimicking the sandcastle worm strategy to assemble sand grains. The designed ink proves printability of both planar and higher aspect ratio structures printed via extrusion based bioprinting.