Fig. 7
ZnO NPs and ZnCl2 inhibit proteasome activity in cells. a RAW264.7 cells were exposed for 6 h to TiO2 NPs (c) or ZnO (d) NPs at 15 µg/mL and protein aggregation was determined using the PROTEOSTAT® reagent (red). Cell nuclei were counterstained with DAPI (blue). No signs of protein aggregation were noted. c ZnO NPs and ZnCl2 triggered inhibition of the 20S proteasome in RAW264.7 cells after 24 h of exposure while TiO2 NPs were ineffective in this assay. Bortezomib (5 nM) was included as a positive control. Data shown are mean values ± S.D. (n = 3). **p < 0.01; ****p < 0.0001 (significant difference between control and treatments)