3.4. Fabrication of Liver-on-a-chip
We used a nonconductive PLA as the printing bioink for the LOC platform. The chip platform was printed on a sterilized glass slide. The PLA-based chip platform was then used for developing a bioprinted liver model by using a coaxial nozzle by directly extruding the HepG2 mixed collagen–alginate bioink from the outer nozzle and gelatin bioink from the inner nozzle. When the LOC was incubated at 37°C, the sacrificial material, that is, gelatin, which lined the inner core region of the construct, dissolved and flowed out, resulting in a lumen-based structure. The longitudinal and cross-sectional images of the LOC with stained hepatocytes are shown in Fig 6. As can be seen in the cross-sectional image, the core/shell model exhibited lumen-based structure formation. Thus, by using the coaxial bioprinting process, a core/shell 3D structure containing an empty tubular passage surrounded by hepatocyte plates that closely resemble the physiological unit of the liver sinusoid was fabricated.