One-step solvothermal synthesis of highly water-soluble, negatively charged superparamagnetic Fe3O4 colloidal nanocrystal clusters

Abstract

Highly charged hydrophilic superparamagnetic Fe3O4 colloidal nanocrystal clusters with an average diameter of 195 nm have been successfully synthesized using a modified one-step solvothermal method. Anionic polyelectrolyte poly(4-styrenesulfonic acid-co-maleic acid) sodium salt containing both sulfonate and carboxylate groups was used as the stabilizer. The clusters synthesized under different experimental conditions were characterized with transmission electron microscopy and dynamic light scattering; it was found that the size distribution and water dispersity were significantly affected by the concentration of the polyelectrolyte stabilizer and iron sources in the reaction mixtures. A possible mechanism involving novel gel-like large molecular networks that confined the nucleation and aggregation process was proposed and discussed. The colloidal nanocrystal clusters remained negatively charged in the experimental pH ranges from 2 to 11, and also showed high colloidal stability in phosphate buffered saline (PBS) and ethanol. These highly colloidal stable superparamagnetic Fe3O4 clusters could find potential applications in bioseparation, targeted drug delivery, and photonics.

Liquid-phase deposition of TiO2 nanoparticles on core–shell Fe3O4@SiO2 spheres: preparation, characterization, and photocatalytic activity

“…The superparamagnetic Fe 3 O 4 spheres were prepared using a modified one-step solvothermal method (Gao et al 2013;Liu et al 2009). In a typical synthesis procedure, 1.5 g of PSSMA was dissolved in 60 mL EG under magnetic stirring to form a clear solution, followed by the addition 2.0 g of FeCl 3 Á6H 2 O and 4.5 g of NaAc.…”

“…The synthesis was carried out according to the previously reported method with minor modification (Gao et al 2013;Luo et al 2010). 0.1 g of the obtained Fe 3 O 4 particles was ultrasonically dispersed into the mixture solution of 80 mL of ethanol, 20 mL of water, and 4.0 mL of concentrated NH 3 ÁH 2 O.…”

“…Monodisperse Fe 3 O 4 colloidal spheres consisting of multiple single-domain magnetic nanocrystals were prepared via a modified hydrothermal method based on high-temperature reduction of Fe(III) salts with EG in the presence of NaAc and PSSMA. PSSMA, an anionic polyelectrolyte containing both sulfonate and carboxylate anionic groups, is used as stabilizer to control the nucleation and clustering-based growth of the colloidal spheres (Gao et al 2013). Figure 1a and b shows the SEM and TEM images of the as-prepared Fe 3 O 4 spheres, respectively; it was demonstrated that nearly spherical nanocrystal clusters had sizes ranging from 175 to 215 nm with an average diameter of about 200 nm.…”

Reduction kinetics of lanthanum ferrite perovskite for the production of synthesis gas by chemical-looping methane reforming

“…The high-solution XPS of Fe2p exhibits two peaks at 710.1 and 723.7 eV, which correspond to the peaks of Fe2p 3/2 and Fe2p 1/2 in fresh LaFeO 3 , respectively. After exposing to methane, Fe2p 3/2 peak widens and shake-up satellite decreases, which indicates that surface Fe 3 þ species gain electron and gradually reduce to Fe 2 þ with methane (Gao et al, 2013). The O1s XPS peaks at 529.0 is attributed to lattice oxygen in perovskite oxide (metaloxygen bond), while 531.1 and 532.4 eV are assigned to weakly bound oxygen on the surface (O 2 species that are molecularly adsorbed in the subsurface regions of oxygen-deficient perovskitetype compounds) or/and to the surface hydroxyls (Jirátová et al, 2009).…”

Construction of a Biomimetic Magnetosome and Its Application as a SiRNA Carrier for High‐Performance Anticancer Therapy

“…The distance between the two adjacent planes in a specific direction was 0.29 nm, which corresponds to the lattice spacing of (220) planes for cubic Fe 3 O 4 magnetite. [22] The size of the clusters could also be controlled from ≈30 to ≈200 nm by regulating the amount of NaOH and O 2 , as well as the ratio of EG/DEG (Figure 1b). With the growing cluster size from 31 to 196 nm, the grain size slightly increased from 10.5 to 12.9 nm, which was calculated from vibrating sample magnetometer (VSM) data ( Figure S5 and Table S1, Supporting Information), while the PEI content and zeta potential gradually increased from 6.05% to 19.78% and +20.8 to +41.5 mV, respectively ( Figure S6 and Table S2, Supporting Information).…”