S1-4 aptamer-mediated iron oxide nanoparticles for targeted magnetic hyperthermia in MCF-7 breast cancer cells

Objective: To develop S1-4 aptamer-conjugated citric acid-coated Fe₃O₄ nanoparticles and evaluate their targeting ability and magnetic hyperthermia effect against MCF-7 breast cancer cells.Methods: Citric acid-coated Fe₃O₄ nanoparticles were synthesized by chemical co-precipitation and subsequently conjugated with the S1-4 aptamer to fabricate S1-4 aptamer-conjugated citric acid-coated Fe₃O₄ nanoparticles. The nanoparticles were characterized by X-ray diffraction, transmission electron microscopy, dynamic light scattering, zeta potential analysis, Fourier transform infrared spectroscopy, and vibrating sample magnetometry. Biocompatibility was assessed in MCF-7 and MEF cells; cellular targeting was examined by Prussian blue staining; and the magnetic hyperthermia effect under an alternating magnetic field was evaluated by cell viability, live/dead staining, and apoptosis assays.Results: Compared with citric acid-coated Fe₃O₄ nanoparticles, S1-4 aptamer-conjugated citric acid-coated Fe₃O₄ nanoparticles exhibited a larger hydrodynamic diameter (17 ± 4 nm vs. 8 ± 3 nm) and a more negative surface charge (-26.7 ± 0.3 mV vs. -19.7 ± 0.5 mV). Fourier transform infrared spectroscopy confirmed successful aptamer conjugation. Both nanoparticles demonstrated good biocompatibility in MCF-7 and MEF cells. Prussian blue staining demonstrated stronger cellular uptake of S1-4 aptamer-conjugated citric acid-coated Fe₃O₄ nanoparticles in MCF-7 cells. Under alternating magnetic field exposure, S1-4 aptamer-conjugated citric acid-coated Fe₃O₄ nanoparticles produced a significantly greater hyperthermia effect than the controls, resulting in reduced cell proliferation and increased apoptosis in MCF-7 cells (P < 0.01).Conclusions: S1-4 aptamer-mediated Fe₃O₄ nanoparticles demonstrated active targeting ability and enhanced the antitumor effect of alternating magnetic field-mediated magnetic hyperthermia in breast cancer cells and maintained low cytotoxicity under the tested conditions, suggesting that they may be a feasible platform for targeted magnetic hyperthermia.