Preparation and Properties of Magnetic Composites γ-Fe₂O₃/SiO₂/Aptamer(FAS9) for Magnetic Resonance Hyperthermia

Powders of maghemite gamma-Fe2O3 with an average diameter of 8 nm, gamma-Fe2O3/SiO2 composites with an agglomerate diameter of about 50 nm and a size of interspersed gamma-Fe2O3 particles of 6 nm, and gamma-Fe2O3/SiO2/aptamer(FAS9) composites were synthesized by chemical deposition. Mossbauer 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 gamma-Fe2O3 powders to 3 Oe for the gamma-Fe2O3/SiO2 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 Fe2O3/SiO2 composite (Delta T approximate to 16(degrees)C) turned out to be higher than that of the pure gamma-Fe2O3 powder (Delta T approximate to 10(degrees)C). It has been experimentally shown that temperature increment Delta T is proportional to the square of the microwave field amplitude. It has been shown that the composition gamma-Fe2O3/SiO2/aptamer FAS9 is able to effectively bind to tumor cells, and FMR hyperthermia leads to a decrease in the viability of tumor cells.