Synthesis and Morphology of Platelet α-FeOOH and γ-Fe₂O₃ Nanoparticles for Cancer Therapy Using Hysteresis-Loss Heating

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The morphology of platelet α-FeOOH, a precursor for synthesizing γ-Fe₂O₃ particles for use in cancer therapy by hysteresis-loss heating, was investigated with the aim of reducing the size of γ-Fe₂O₃ particles. The α-FeOOH particles were synthesized by the precipitation of ferric ions in alkaline solution containing ethanolamine, and crystals were grown via hydrothermal treatment. The particle length of α-FeOOH was reduced on lowering the precipitation temperature and maintaining it in the range from −3°C to 6°C, whereas the ratio of the long and short axes was maintained. The axial ratio of the α-FeOOH particles was remarkably affected by the precipitant's aging temperature in the range of 4–60°C, and became smaller when the aging temperature was lowered. The addition of Si was effective for reduction of the particle length of α-FeOOH. Platelet α-FeOOH particles with a particle length of ~40 nm and an axial ratio of ~1.5 were obtained by using Si as an addictive and employing precipitation, aging, and hydrothermal treatment temperatures of −3.5°C, 4°C, and 150°C, respectively.