Hepg2

A human hepatoma cell line (HepG2) was purchased from the Bioresource Collection and Research Center (Hsinchu, Taiwan) and grown in Dulbecco’s Modified Eagle Medium (Hyclone, a brand of General Electric Company, Boston, MA, USA) containing 4.5 g/L glucose, 100 units/mL penicillin, 100 µg/mL streptomycin, and 10% foetal bovine serum (Gibco, Grand Island, NY, USA) in a humidified atmosphere with 5% CO₂ at 37 °C. Cell viability was measured by a quantitative colorimetric assay with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). After removing the media, MTT solution (0.1 mg/mL) was added to each well for 3 h incubation at 37 °C, and the optical density (OD) was measured at 570 nm with a microplate reader (BioTek Instruments, Inc., Winooski, VT, USA).

To demonstrate the device capabilities for tumor spheroid formation, drug testing, and flow cytometry analysis, human hepatocellular carcinoma cells (HepG2, 60025, Bioresource Collection and Research Center, Hsinchu, Taiwan) are utilized for the cell experiments in this study. The stocks of HepG2 cells are cultured in growth medium composed of Minimum Essential Media (MEM) (Gibco 41090-036, Invitrogen Co. Carlsbad, CA) with 10% v/v fetal bovine serum (Gibco 10082, Invitrogen), 1% Antibiotic-Antimycotic (Gibco 15240, Invitrogen), 1% sodium pyruvate (Gibco 11360, Invitrogen) and 1% non-essential amino acids (Gibco 11140, Invitrogen). The cells are maintained under 5% CO₂ in T25 or T75 cell culture flasks (Nunc 156367, Thermo Scientific Inc., Rochester, NY), and passaged by dissociation with 0.25% trypsin-EDTA (Gibco 25200, Invitrogen) every three days. Cell suspensions for the experiments are made by centrifugation of dissociated cells at 1000 rpm for 5 minutes at room temperature. The culture medium is changed every other day for the cell stocks during the experiments.

The hepatoma cell lines, HepG2 and Hepa1-6, were purchased from the Bioresource Collection and Research Center (Food Industry Research and Development Institute, Hsinchu, Taiwan). Cells were maintained in Dulbecco’s modified Eagle medium (Hyclone, South Logan, UT, USA) supplemented with 10% heat-inactivated fetal bovine serum.

The HCC cell lines Hep3B, HepG2 and Huh7 were purchased from BCRC (Bioresource Collection and Research Center, Hsinchu, Taiwan). All cell lines were authenticated annually using STR analysis and were tested negative for mycoplasma. Cells were cultured in an appropriate medium according to the suggestions from the BCRC website. All media components were purchased from Invitrogen (Carlsbad, CA, USA).