Figure 1: The use of 0.1% chitosan as stabilizer provided a homogeneous SeNPs suspension with around 80-90% of NPs in the range 40-60 nm. Cell viability of HepG2 cells exposed to Ch-SeNPs and Se IV decreased in a dosedependent manner. (A) Transmission electron microscopy of Ch-SeNPs synthesized in the presence of 0.1% chitosan. (B) Cell viability of HepG2 cells exposed to different concentrations of Ch- SeNPs, Se IV and the synthesis media. The MTT assay showed that high concentrations (10-20 μg ml-1 of Ch-SeNPs and Se IV) caused an almost 100% decrease in the cell viability. Exposure conditions of 1 μg ml-1 of Ch- SeNPs induced a 30% decrease in cell viability and were selected for further experiments.