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.