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Page 6 of 16 Wang et al. Microstructures 2023;3:2023042 https://dx.doi.org/10.20517/microstructures.2023.46

10 min, and cell viability was investigated, as mentioned above. Triplicate samples were used for each
measurement.

Anticancer effect of gelatin/Fe O porous scaffolds
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The three culture modes were also used for the investigation of the anticancer effect of the gelatin and
gelatin/Fe O porous scaffolds. All the experiment procedures were the same as those of agarose/Fe O
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hydrogel discs by using the porous scaffold discs (Φ10 mm × H4 mm). Triplicate samples were used for each
measurement.
RESULTS
Characterization of Fe O NPs
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The morphology and size of the citrate-modified Fe O NPs were characterized by TEM. As shown in
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Figure 2A-C, the NPs displayed a flower-like shape, which should have a good magnetic-thermal conversion
capacity for MH. They had an average size of 30.8 ± 5.7 nm from the TEM images. The hydrodynamic size
of the citrate-modified Fe O NPs was measured in aqueous solution by DLS, and the hydrodynamic size
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was 108.5 ± 28.5 nm [Figure 2D].
Characterization of agarose/Fe O hydrogels and gelatin/Fe O porous scaffolds
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The agarose/Fe O hydrogel discs are shown in Figure 3A. As the concentration of Fe O NPs increased, the
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appearance of agarose/Fe O hydrogel changed from transparent to black. SEM observation of the
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lyophilized agarose/Fe O hydrogel discs showed that the agarose hydrogels with different amounts of Fe O 4
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NPs had similar structures [Figure 3B]. They had spindle-shaped pores. The gelatin porous scaffold without
Fe O NPs was white, while the gelatin/Fe O porous scaffolds became gray (gelatin/Fe O -5), dark gray
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(gelatin/Fe O -10), and black (gelatin/Fe O -20) [Figure 3C]. The gelatin and gelatin/Fe O porous scaffolds
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had the same pore structures. They had large spherical pores that were surrounded by some small pores
[Figure 3D]. The large spherical pores were controlled by the ice particulates that were used as a porogen
material. The results indicated that the embedding of Fe O NPs did not affect the pore structures of
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hydrogels and porous scaffolds.
Magnetic thermal property of Fe O NPs in different matrices
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The magnetic thermal properties of Fe O NPs in PBS, agarose hydrogels, and gelatin porous scaffolds were
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investigated by applying AMF (frequency: 373.6 kHz; field: 130 Gauss) for 10 min, and the results are shown
in Figure 4 and Table 1. The temperature of PBS, agarose hydrogels, and gelatin porous scaffolds without
Fe O NPs had no obvious change after AMF irradiation [Figure 4A and Table 1]. The results suggested that
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PBS, agarose hydrogels, and gelatin porous scaffolds had no magnetic-thermal conversion capacity in the
absence of Fe O NPs. When Fe O NPs were added to PBS, hydrogels, and porous scaffolds, the
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temperature change significantly increased under AMF irradiation.
The temperature change increased with the irradiation time and became plateau after 10 min AMF
irradiation [Figure 4B-D]. The temperature change of free Fe O -5, agarose/Fe O -5, and gelatin/Fe O -5
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was 24.1 ± 1.7 °C, 14.0 ± 0.3 °C, and 5.2 ± 0.3 °C, respectively, after 10 min AMF irradiation
[Figure 4B and Table 1]. The temperature change of free Fe O -10, agarose/Fe O -10, and gelatin/Fe O -10
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increased to 38.3 ± 1.1 °C, 22.8 ± 1.7 °C, and 9.1 ± 0.5 °C, respectively, after 10 min AMF irradiation
[Figure 4C and Table 1]. The temperature change of free Fe O -20, agarose/Fe O -20, and gelatin/Fe O -20
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increased to 65.7 ± 1.4 °C, 33.8 ± 1.0 °C, and 13.2 ± 0.4 °C, respectively, after 10 min AMF irradiation
[Figure 4D and Table 1]. The results indicated that the temperature change of free Fe O NPs, agarose/
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Fe O4, and gelatin/Fe 3O 4 was positively correlated with the concentration of Fe 3O4 NPs. Increasing
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the concentration of Fe O NPs resulted in a bigger temperature change.
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