Preparation and Properties of Magnetic Composites γ-Fe 2 O 3 /SiO 2 /Aptamer(FAS9) for Magnetic Resonance Hyperthermia

Powders of maghemite γ-Fe 2 O 3 with an average diameter of 8 nm, γ-Fe 2 O 3 /SiO 2 composites with an agglomerate diameter of about 50 nm and a size of interspersed γ-Fe 2 O 3 particles of 6 nm, and γ‑Fe 2 O 3 /SiO 2 /aptamer(FAS9) composites were synthesized by chemical deposition. Mössbauer spectra were measured, the static and dynamic magnetic properties of the powders were studied, and the coercive force was determined, which decreases from 14 Oe for γ-Fe 2 O 3 powders to 3 Oe for the γ-Fe 2 O 3 /SiO 2 composite. It is shown that the particle blocking temperature is close to room temperature. The increment of temperature of the powders was measured in the ferromagnetic resonance mode; the temperature of the Fe 2 O 3 /SiO 2 composite (Δ T ≈ 16°C) turned out to be higher than that of the pure γ-Fe 2 O 3 powder (Δ T ≈ 10°C). It has been experimentally shown that temperature increment Δ T is proportional to the square of the microwave field amplitude. It has been shown that the composition γ-Fe 2 O 3 /SiO 2 /aptamer FAS9 is able to effectively bind to tumor cells, and FMR hyperthermia leads to a decrease in the viability of tumor cells.