8.40 mg of the triethoxysilane-modified PNIPAM polymer (Mn = 2750 g•mol⁻¹, Mw/Mn < 1.8) was dissolved in 99.8% ethanol (3 mL). The solution was introduced into a glass vial containing 30 mL of the previously synthesized FexOy@SiO2 nanoparticles, and the mixture was maintained at 28 °C with stirring for 72 hours. Hexane (30 mL) and 99.8% ethanol (18 mL) were added to the FexOy@SiO2@PNIPAM mixture, forming a homogeneous solution. The nanoparticles were centrifuged at 9000 rpm for 45 minutes, followed by discarding the supernatant. Ethanol (10 mL) was added to the orange precipitate, which was sonicated for 5 minutes. Hexane (20 mL) was introduced, and the sample was centrifuged at 9000 rpm for 30 minutes. This purification process was repeated four times, with the supernatant discarded after each cycle. After the final centrifugation, distilled water (9.9 mL) was added to the precipitate to achieve a 5 mg•mL⁻¹ concentration. The solution underwent 30 minutes of sonication, followed by standing at room temperature in an open vial for 30 minutes to evaporate any hexane residues.