Figure 3.

Nanoparticle-mediated catalase delivery protected human neurons from H₂O₂-mediated cytotoxicity. Primary cultured human neurons were exposed to H₂O₂ (50 μM, 24 h) with or without 200 μg/ml of Nano-CAT or Nano-CON. Cell survival was assayed using the trypan blue exclusion assay on three biological replicates with each condition in multiple replicates (a–g). Representative micrographs from five random fields are shown for untreated control (a); NP-alone control, Nano-CAT (b) and Nano-CON (c); H₂O₂-alone (d) or with Nano-CAT (e) or with Nano-CON (f). Scale bar =50 μm. Trypan blue-positive cells were considered as dead cells (represented by arrow), whereas cells that excluded trypan blue (arrowhead) were counted as live and the percentage of trypan blue-positive cells was calculated (g). Cell membrane integrity was measured after 24 h of treatment by LDH assay (h). DNA fragmentation was quantified by ELISA to detect neuronal apoptosis (i). Data are presented as mean ±S.E.M. of triplicates and representative of three biological replicates. Symbols indicate the relative level of the significance compared with vehicle control (***P<0.001) or comparisons with H₂O₂-alone (^##P<0.01 and ^###P<0.001).