Core-shell Fe₃O₄@SiO₂nanoparticles synthesized with well-dispersed hydrophilic Fe₃O₄seeds

Abstract

Silica coated magnetite (Fe3O4@SiO2) core-shell nanoparticles (NPs) with controlled silica shell thicknesses were prepared by a modified Stöber method using 20 nm hydrophilic Fe3O4 NPs as seeds. The core-shell NPs were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), selected area electron diffraction (SAED), and UV-Vis adsorption spectra (UV-Vis). The results imply that NPs consist of a crystalline magnetite core and an amorphous silica shell. The silica shell thickness can be controlled from 12.5 nm to 45 nm by varying the experimental parameters. The reaction time, the ratio of TEOS/Fe3O4, and the concentration of hydrophilic Fe3O4 seeds were found to be very influential in the control of silica shell thickness. These well-dispersed core-shell Fe3O4@SiO2 NPs show superparamagnetic properties at room temperature.

Fe3O4/SiO2 Core/Shell Nanocubes: Novel Coating Approach with Tunable Silica Thickness and Enhancement in Stability and Biocompatibility

“…Further, the intensity of the silicon (Si) peak was increased sharply as observed from the EDS analysis ( Figure 7c). We also studied the influence of Fe 3 O 4 nanocubes concentration on the coating process and found that the concentration of the Fe 3 O 4 does not affect the thickness of the silica shell, and this result was in agreement with the earlier report [4].…”

“…However in their study, they coated the noble metal with silica and not magnetic materials. Hence the coating process involves mainly two reaction of nucleation (hydrolysis) and growth (condensation), and the silica tends to predominantly coat onto the magnetic nanoparticles as the growth rate is much higher than nucleation rate [4], one must be very careful of reaction parameters optimization. Based on the reported method, it was found that lower temperature, lower pH value, lower TEOS concentration, and less H 2 O are predominant in facilitating the condensation process and consequently the coating process [18][19][20].…”

“…The cultured cells having 80~90% confluency were collected after treating them with 0.25% trypsin-EDTA and centrifuged at 1000 rpm for 1 min. Approximately, 1.0×10 4 HeLa cells were kept in the suspension load on cell culture plates and incubated for 12 hr. Then, nanoparticles with different concentration (0.01, 0.1 and 1 mg/ml) are loaded on HeLa cells and incubated for different times and up to 72 hours.…”

Composites of Fe3O4/SiO2from Natural Material Synthesized by Co-Precipitation Method

“…The size of the Fe 3 O 4 @a-SiO2 particle was about ~25 nm and the thickness is ~9 nm. Thus, the Fe 3 O 4 /a-SiO 2 nanocomposites have successfully formed a Fe 3 O 4 @a-SiO 2 core shell [14,18]. There were significant different shape and size of the composite particles of Fe 3 O 4 @ a-SiO 2 amorphous (#sample 1) and Fe 3 O 4 @ c-SiO2 (crystal), as shown in Figure 2 (a) and Figure 2 (b); composite particle size of Fe3O4/a-SiO 2 was greater than the particle size of the Fe 3 O 4 @c-SiO 2 composite.…”

<strong>Effect of Novel Magnetic Nanoparticles on Morphology properties of Polyurethane Foam</strong>

“…The MNPs and MNPs/silica nanoparticles were synthesized according to previous report [3]. Then 1 mL of chloropropyltrimethoxysilane was dissolved in toluene.…”