Evaluation of the performance of Fe3O4/MnO2@doxorubicin hybrid nanozymes on multicellular structure and their therapeutic management to limit the growth of human breast cancer cells

Doxorubicin (DOX) is the most common treatment for breast cancer, but its effectiveness is limited by drug resistance and dose variability. Evidence suggests that nanozymes can significantly improve drug penetration and effectiveness in breast cancer treatment, owing to their stable and targeted catalytic properties. However, their varied responses and concentration-dependent toxicities present challenges. After developing pH-sensitive Fe3O4/MnO2@DOX hybrid nanozymes (FMDHN) and evaluating their physicochemical and functional properties, their efficacy was investigated on MCF-7 cells using both two-dimensional and spheroid models. Our findings reveal that FMDHNs, sized 150–270 nm, inhibit MCF-7 cell growth through drug release triggered by acidity and photothermal therapy (PTT). The catalytic efficiency of FMHN in generating O2 and ·OH further enhances cancer cell suppression. Doubling the effective concentrations of FMHN and DOX by transitioning from two-dimensional to spheroid cell structures could adversely affect normal cells, while a synergistic approach combining the DOX and FMHN effectively inhibits MCF-7 cell growth at non-toxic dose. Combining FMDHN with PTT enhances this inhibition, lowering the effective dose to 1.08 μg/mL and effectively managing toxicity. The cytotoxicity mechanism in MCF-7 spheroids shows that PTT with FMDHN significantly elevates pro-inflammatory cytokines, including TNF-α, CASP9, CASP7 and CASP3. Optimizing the concentration of pH-sensitive nanozymes based on their synergistic effects can minimize side effects and maximize their breast cancer treatment potential.