Double‐Interpenetrating Composite Bioink for Multi‐Component 3D Bioprinting and Biofabrication

ABSTRACT Bioinks that can yield complex structures under ambient conditions are an important aspect for the translation of 3D bioprinting (3DBP). Bioinks are typically tailored for a specific application to fulfill distinct requirements, which in turn might diminish their broader utility. While bioprinting has advanced significantly and can yield objects of considerable complexity, recapitulating the spatial and mechanical attributes of native tissues will require a multimaterial assembly step. Here, we present a bioink system possessing physical and ionic crosslinks based on a double interpenetrating network (dIPN) of carboxylated agarose (CA) and alginate (Alg). The CAAlg system combines the key attributes of both hydrogel systems, resulting in excellent shear thinning and recovery of shear deformation, thus enabling reliable printing at low pneumatic pressures under ambient conditions. The dIPN confers immediate physical stability to printed structures, allowing subsequent assembly of printed objects into complex 3D structures by exploiting interfacial ionic bonding, thus obviating the need for a support bath. Low pneumatic pressure ensures high cell viability during and after printing, and in sum, paves the way for the exploration of CAAlg in the room‐temperature biofabrication of multi‐component assemblies of disparate and bespoke soft materials into a single construct.