Fig. 4.

Mn-ZnO₂ NP-mediated modulation of p53 proteins and cell-based killing efficiency. (a) The proposed mechanism on tumor cell death induced by Mn-ZnO₂ NPs via the regulation of p53 proteins. (b) Western blotting of Mutp53 in MDA-MB-231 cells after various treatments (non-treated control, MnCl₂, ZnCl₂, H₂O₂, ZnO₂ NPs, or Mn-ZnO₂ NPs). (c) Semi-quantification of the Mutp53 level shown in b. *p < 0.05, **p < 0.01. (d) Fluorescence images of ROS production in MDA-MB-231 cells after treated with Mn-ZnO₂ NPs or Mn-ZnO₂ NPs + NAC. (e) Western blotting of Mutp53 in MDA-MB-231 cells after the Mn-ZnO₂ NPs treatment without or with NAC. (f) Western blotting of ATM, WTp53, and Bax in MDA-MB-231 cells after various treatments (non-treated control, ZnCl₂, MnCl₂, ZnO₂ NPs, or Mn-ZnO₂ NPs). (g) Western blotting (WB) of total ubiquitination (Ub) and K48-polyubiquitination (K48-Ub) of the immunoprecipitated (IP) p53 in MDA-MB-231 cells after the Mn-ZnO₂ NPs treatment without or with MG132. (h) Viability of MDA-MB-231 cells after various treatments. Data are expressed as mean ± SD (n = 6). *p < 0.05, **p < 0.01. (i) Viability of MDA-MB-231 cells treated with ZnO₂ NPs or Mn–ZnO₂ NPs, respectively. Data are expressed as mean ± SD (n = 6). *p < 0.05, **p < 0.01. (j) Fluorescence images of MDA-MB-231 cells after different treatments (non-treated control, Zn²⁺ + Mn²⁺, ZnO₂ NPs, or Mn-ZnO₂ NPs). Cells were stained live (green) with calcein-AM and dead (red) with PI.