Figure 4.

(A) Confocal images of spheroids incubated with the FITC-labeled polyampholyte (15 min) before and after washing. Scale bar = 200 μm. (B) Toxicological challenge of HepG2 spheroids (10 spheroids) against doxorubicin determined by the WST-1 assay. The data are presented as percentage viability relative to doxorubicin untreated spheroids for each freezing condition ± SD for three biological repeats. IC₅₀ values are indicated in the legend. (C) HepG2 CYP spheroid Cytochrome P450 3A4 (CYP3A4) activity. CYP3A4 activity was measured before and after freezing at different time intervals post-thaw, having been cryopreserved with 10% DMSO or 10% DMSO combined with 20 mg mL^–1 of the polyampholyte. The data are represented as mean CYP activity ± SD from three independent repeats. CYP activity is reported in relative light units (RLU) per 12,000 cells (3 spheroids).