ZnAs@SiO2 NPs inhibit proliferation of HCC cells in vitro. (A) Cell viability of MHCC97L, Hep3b, HepG2, and Bel7402 cells treated with different concentrations of ATO or ZnAs@SiO2 NPs for 24 h (n = 3). (B) mRNA levels of proliferation indicators Ki67 and PCNA in MHCC97L and Hep3b cells after treatment with ATO or ZnAs@SiO2 NPs for 24 h. (C) Morphology of MHCC97L and Hep3b cells before and after treatment with PBS, ATO or ZnAs@SiO2 NPs for 24 h. Scale bar, 200 µm. (D) Colony forming ability of MHCC97L and Hep3b cells after treatment with PBS, ATO, or ZnAs@SiO2 NPs for 24 h. (E, F) Quantification of colony formation assay in MHCC97L and Hep3b cells. *, P < 0.05; **, P < 0.01; ***, P < 0.001.