Viability of printing constructs
To print the cell-laden gelatin/alginate/collagen gel, one important criterion is that the material should come out of the nozzle with minimum applied shear force. Otherwise, the applied shear force may damage the cells and reduce the cell viability in the printed constructs. We checked the cell viability using the live/dead assay that can be imaged in the printed construct after 3D printing. As shown in Fig. 4, there was minimal cell death caused by the printing process, and the viability of HCECs in the printed construct was found to be 94.6 ± 2.5%. Thus, the printing cell-laden materials and parameters used in this experiment did not have any harmful effect on the encapsulated cells and can support cell viability without disruption of the constructs. Although the long-term stability of the constructs during the culture time in the medium is a requirement for potential applications in 3D tissue regeneration, alginate’s nondegradable property also negatively affects bioprinted cell behaviour and tissue formation.