Magnetic properties of γ-Fe 2 O 3 nanoparticles in a porous SiO 2 shell for drug delivery

• Published in: Journal of physics. Condensed matter Vol. 33; no. 6; p. 065301
• Main Authors: Kamali, S, Yu, E, Bates, B, McBride, J R, Johnson, C E, Taufour, V, Stroeve, P
• Format: Journal Article
• Language: English
• Published: England 24.11.2020
• ISSN: 1361-648X

A method is presented for synthesizing core-shell nanoparticles with a magnetic core and a porous shell suitable for drug delivery and other medical applications. The core contains multiple γ-Fe O nanoparticles (∼15 nm) enclosed in a SiO (∼100-200 nm) matrix using either methyl (denoted TMOS-γ-Fe O ) or ethyl (TEOS-γ-Fe O ) template groups. Low-temperature Mössbauer spectroscopy showed that the magnetic nanoparticles have the maghemite structure, γ-Fe O , with all the vacancies in the octahedral sites. Saturation magnetization measurements revealed that the density of γ-Fe O was greater in the TMOS-γ-Fe O nanoparticles than TEOS-γ-Fe O nanoparticles, presumably because of the smaller methyl group. Magnetization measurements showed that the blocking temperature is around room temperature for the TMOS-γ-Fe O and around 250 K for the TEOS-γ-Fe O . Three dimensional topography analysis shows clearly that the magnetic nanoparticles are not only at the surface but have penetrated deep in the silica to form the core-shell structure.