Figure 4. AgNP exposure increased numbers of apoptotic TUNEL+ HNPC. A.

AgNP-exposure for two weeks increased the cell death in HNPCs, seen as increased number of TUNEL-+ cells. Both Au- and AgNPs induced cell death of HNPCs indicated by the increased number of TUNEL-+ cells and -aggregates. The presented data are representative images of 6 spheres per section from two independent experiments. Blue staining, DAPI; red staining, TUNEL; Au 20∶800, gold 20 nm and 800 particles/cell; Au 80∶800, gold 80 nm and 800 particles/cell; Ag 20∶800, silver 20 nm and 800 particles/cell; Ag 80∶800, silver 80 nm and 800 particles/cell; AgNO₃ 1.0, silver nitrate 1.0 mg/ml. Scale bar equal 214 µm. B. Only AgNPs significantly induced cell death in HNPCs. Evaluation of the data presented under A, showing the number of TUNEL-+ cells/mm₂ of the HNPC neurospheres. Au 20∶50, gold 20 nm and 50 particles/cell; Au 20∶800, gold 20 nm and 800 particles/cell; Au 80∶50, gold 80 nm and 50 particles/cell; Au 80∶800, gold 80 nm and 800 particles/cell; Ag 20∶50, silver 20 nm and 50 particles/cell; Ag 20∶800, silver 20 nm and 800 particles/cell; Ag 80∶50, silver 80 nm and 50 particles/cell; Ag 80∶800, silver 80 nm and 800 particles/cell; AgNO₃ 0.5, silver nitrate 0.5 mg/ml; AgNO₃ 1.0, silver nitrate 1.0 mg/ml. *p<0.05 compared to control, **p<0.01 compared to control, ***p<0.001 compared to control.