*2.11. Apoptosis and Necrosis*

CT26WT cells were seeded into 24 wells at a concentration of 2 <sup>×</sup> 105 cells/well and cultured for 24 h. Then, a high dosage of bi-HNTs were added into the cell culture medium (150 μg/mL) and incubated for 24 h. Then 3 <sup>×</sup> 105 cells were collected and suspended in 500 <sup>μ</sup>L of 1<sup>×</sup> binding Buffer, then mixed with 5 μL of Annexin V-FITC and 5 μL of propidium iodide (Sigma Aldrich, St. Louis, MO, USA). Cell suspension mixtures were incubated in the dark at room temperature for 5 min. Then samples were examined by flow cytometry (Thermo Fisher Scientific, Waltham, MA, USA) at 488/530 nm (Ex/Em). Beside the resuspended cells, we kept a portion of attached cells in 24 wells and stained by 5 μL of Annexin V-FITC and 5 μL of propidium iodide as well.
