Study of Brownian motion of magnetic nanoparticles in viscous media by Mössbauer spectroscopy

The Mossbauer spectroscopy method was used to study the Brownian motion of magnetic nanoparticles in viscous media of glycerol solution, simulating cell cytoplasm. We used samples of two types of ferrofluids based on the magnetite nanoparticles with average hydrodynamic sizes 140 and 40 nm. The nanoparticles were enriched by 57Fe isotope to compensate the decrease of the Mossbauer effect probability in the liquid media. In order to maximize the viscosity coefficient we dissolved both samples in glycerol to receive more than 90% glycerol solution. We carried out two experimental series at different temperatures on ferrofluids dissolved in glycerol and ferrofluids dried to the powder-state to exclude the influence of the temperature dependent Neel relaxation. The analysis of the spectra allowed us to reveal the Brownian movement of the particles and to evaluate intrinsic dynamical parameters of the model viscous medium.