Apoptosis-Inducing Effect of Cytocompatible Poly(Acrylic Acid)-Coated Temperature-Sensitive Mn_0.9Zn_0.1Fe₂O₄ Magnetic Fluid on Breast Cancer Cells MCF-7

Cancer remains a challenging disease to treat due to the limitations of conventional therapies, including toxicity to healthy cells and drug resistance. This underscores the need for alternative treatment modalities to target tumors more effectively while minimizing side effects. Magnetic nanoparticles (MNPs) have emerged as promising agents in the realm of cancer therapy, particularly through magnetic fluid hyperthermia (MFH), which employs MNPs to generate localized heat in tumor tissues using an alternating magnetic field (AMF), while sparing healthy cells. This present study focused on the synthesis of self-regulating, temperature-controlled, poly(acrylic acid) (PAA)-coated manganese-zinc ferrite nanoparticle-based magnetic fluid (MF) to enhance the biocompatibility of MF and its therapeutic efficacy. The biocompatibility and cellular uptake of the synthesized MF were investigated by using the MTT assay and Prussian blue staining. Quantitative assessment of the internalization of MNPs was carried out using inductively coupled plasma-mass spectrometry (ICP-MS). The study further analyzed the immediate and 24 h delayed cytotoxic effects of MFH on breast cancer cells (MCF-7) and noncancerous murine fibroblasts (McCoy). The mode of cell death induced immediately and after 24 h post-MFH was examined using Hoechst/propidium iodide staining and flow cytometry. Both MCF-7 and McCoy cells exhibited favorable biocompatibility and substantial internalization of MF, with a significant induction of apoptosis after MFH. A 24 h incubation period post-MFH enabled cells to transition from early- to late-stage apoptosis in both cell lines, resulting in nearly complete cell death. This research establishes a foundational framework for investigating the application of PAA-coated biocompatible MNPs, with the goal of further exploring their use in breast cancer spheroids and/or in vivo animal models to develop MFH-based cancer treatment strategies.