SEM image of Caco-2 cells exposed for 72 h at 100 μg/mL of STNPs. Caco-2 cells were grown in a bicameral chamber (PET, pores 1 μm) and differentiated for 21 days. The cells were exposed to STNPs (100 μg/mL). After 72 h incubation, the cells were washed, fixed and dehydrated. They were examined by SEM. A) Enlargement X 2000 B) Enlargement X 16000. Control, T-Lite and T-Lite DA are in lanes 1, 2, 3 respectively.