Topotactic transformation is an emerging strategy for synthesizing materials with exotic functional properties. In this report, instead of producing new crystals with related structures, we exploited the topotactic transformation phenomenon to spontaneously produce compositionally diverse nanostructures on the transforming substrate. The surface of magnetite nanoparticles (Fe3O4 NPs) is topotactically transformed into maghemite (γ-Fe2O3). Benefiting from such oxidation susceptibility of ultrasmall Fe3O4 NPs, we achieved spontaneous growth of metals (Ag, Au, Pt, and Pd), a non-metal (Se), and a metal oxide (MnO2) based nanostructures onto the surface of Fe3O4. No spontaneous growth of nanostructures was observed when the oxidized Fe3O4 NPs were tested, likely due to the loss of the Fe2+-associated mobile electrons. The obtained nanostructures displayed appreciable antioxidant activities, which we utilized to effectively treat inflammation in the intestines. It is anticipated that this synthetic route, based on topotactic transformation, represents a significant advancement in synthesizing various chemically diverse hetero-nanostructures.
Keywords: Anti-inflammatory Therapy; Magnetite; Topotactic Transformation; nanozymes; reactive oxygen species.
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