4.7. Drug Testing

Doxorubicin (1 mg, Sigma Aldrich) was used to verify the drug resistance of the fabricated samples. The doxorubicin was diluted to 0.1, 1.0, and 2.0 μM in cell culture medium and added to the day-7 co-cultured samples, after which further culture was performed in 5% CO₂ at 37 °C. Then, the amounts of MMP2 and MMP9 expressed after one and two days of administration were measured with ELISA, and a Live/Dead assay was used to examine the drug resistance of the fabricated cancer tissues.