Characterization of Magnetite–Silica Magnetic Fluids by Laser Scattering

Abstract

The paper is concerned with structural, morphological and magnetic properties of magnetite-silica magnetic fluids. The granulometric composition of the magnetic fluids was investigated by scanning and transmission electron microscopy, the phase composition was studied by X-ray diffraction and reflection high-energy electron diffraction, and magnetic properties were studied by vibrating sample magnetometry. In order to reveal the particle size distribution, dynamic light scattering and a proposed modification of depolarized dynamic light scattering were employed. The shape and dimensions of magnetic nanoparticles and also their aggregates are described. While the aspect ratio for the aggregates was 0.5–0.99, individual nanoparticles had an average aspect ratio of 0.9 and were nearly spherical. The sedimentation stability of a diluted magnetic fluid was also investigated. When the fluids were diluted 200 times, the stability was partially lost, and the nanoparticles aggregated, thereby forming clusters, and precipitated.

Magnetic Properties of Bacterial Magnetosomes Produced by Magnetospirillum caucaseum SO-1

“…As shown in Figure 4 b, the size distribution of the synthetic nanoparticles was also bimodal and was much wider due to the aggregation processes provoked by dilution [ 37 ]; therefore, as compared to the studied bacterial magnetosomes, such synthetic nanoparticles were not suitable for biomedical use.…”

“…The particle size distribution of the isolated magnetosomes was assessed by dynamic light scattering (DLS) using original measuring equipment developed at Peter the Great St. Petersburg Polytechnic University [ 37 ]. For measurements, a sample of 1 mg of isolated magnetosomes was resuspended in distilled water.…”

“…Crystals appeared to consist of magnetite (98%) and minor goethite (2%). The convergence factor of the calculated and experimental X-ray profiles is as fol- As shown in Figure 4b, the size distribution of the synthetic nanoparticles was also bimodal and was much wider due to the aggregation processes provoked by dilution [37]; therefore, as compared to the studied bacterial magnetosomes, such synthetic nanoparticles were not suitable for biomedical use.…”

“… Comparison of particle size distribution obtained by the dynamic light scattering method: ( a ) the isolated bacterial magnetosomes; ( b ) synthetic magnetite-silica nanoparticles (reprinted from [ 37 ], Velichko, E.; Nepomnyashchaya, E.K. ; Gareev, K.G.…”

Магнитооптические свойства дисперсий наночастиц на основе Fe-=SUB=-3-=/SUB=-O-=SUB=-4-=/SUB=-, полученных методом импульсной лазерной абляции в жидкости

“…Наличие магнитного момента так же уменьшают стабильность, инициируя агрегацию и выпадение частиц в осадок. Поэтому подобные НЧ, как правило, требуют стабилизации поверхности, препятствующей их слипанию и приданию поверхности определенных функциональных свойств [15][16][17]. Функционализация поверхности НЧ может потребоваться, например, для дальнейшей пришивки к ним активных биологических молекул (ДНК аптамеров и пр.…”