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Wang et al. Microstructures 2023;3:2023042 https://dx.doi.org/10.20517/microstructures.2023.46 Page 7 of 16

Table 1. Magnetic thermal property of Fe O NPs in different matrices under AMF irradiation [Mean ± SD (n = 3)]
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ΔT of gelatin
ΔT of agarose Percentage compared Percentage compared
Sample ΔT of PBS (°C) porous scaffold
hydrogel (°C) to free NPs (°C) to free NPs
No Fe O NPs 0.7 ± 0.2 1.0 ± 0.2 / 0.8 ± 0.2 /
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-1
Fe O -5 mg mL 24.1 ± 1.7 14.0 ± 0.3 58.1% 5.2 ± 0.3 21.6%
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-1
Fe O -10 mg mL 38.3 ± 1.1 22.8 ± 1.7 59.5% 9.1 ± 0.5 23.8%
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Fe O -20 mg mL -1 65.7 ± 1.4 33.8 ± 1.0 51.5% 13.2 ± 0.4 20.1%
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Figure 2. TEM images of citrate-modified Fe O NPs at low (A), middle (B), and high magnifications (C). Hydrodynamic size
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distribution of citrate-modified Fe O NPs (D).
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The free Fe O NPs in PBS showed the highest temperature change. The temperature change was reduced to
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51.5%-59.5% when the Fe O NPs were embedded in agarose hydrogels. The temperature change was
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further decreased to 20.1%-23.8% when the Fe O NPs were embedded in gelatin porous scaffolds. The
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results indicated that the matrix where Fe O NPs were embedded could significantly affect the magnetic-
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thermal conversion property of Fe O NPs.
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Anticancer effect of free Fe O NPs
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MH uses the Fe O NPs to absorb and convert magnetic energy to heat and raise the local temperature,
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thereby killing the cancer cells. In this study, MDA-MB-231-Luc cells were cultured in a culture medium
supplemented with free Fe O NPs under different concentrations. Cell viability before and after AMF
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irradiation was investigated by live/dead staining and WST-1 assay [Figure 5]. Before AMF irradiation,