In-Foam Bioprinting: An Embedded Bioprinting Technique with Self-Removable Support Bath.

The emergence of embedded three-dimensional (3D) bioprinting has revolutionized the biofabrication of free-form constructs out of low-viscosity and slow-crosslinking hydrogels. Using gel-based support baths has limitations including lack of proper oxygenation and nutrition and complications with bath removal. Herein, a novel-embedded 3D bioprinting technique is developed with an albumin foam support bath as a promising substitute. The proposed technique, in-foam bioprinting, offers excellent printability and convenience in bath removal while providing cells with easy access to oxygen and nutrients. The foam-based support bath is characterized through foam stability and rheological tests. The bubble size in the foam is measured to study the change in the structure of the bath due to the coalescence of the bubbles over time. Free-form structures are successfully 3D printed with thermoresponsive chitosan-based bioinks to demonstrate the capability of the in-foam bioprinting technique. The viability of bioprinted fibroblast L929 cells is studied over a seven-day period, showing high cell viability of over 97%, which is attributed to the abundance of oxygen and nutrition in the foam support bath. Importantly, in-foam bioprinting is beneficial for biofabricating large samples with a long printing time without jeopardizing cell viability.