Immobilization of magnetic iron oxide nanoparticles on laponite discs – an easy way to biocompatible ferrofluids and ferrogels

Abstract

Magnetic nanocomposites containing iron oxide (maghemite) nanoparticles, well embedded in a synthetic clay matrix (laponite) were prepared by a new one step chemical route and characterized by TEM, XRD, magnetization measurements, Mössbauer spectroscopy, DLS, and MRI measurements. The synthetic procedure leads to non-stoichiometric γ-Fe2O3 with a controllable content in the nanocomposite. Magnetic nanoparticles incorporated in the diamagnetic clay matrix exhibit a mean diameter of 13 nm, superparamagnetic behavior with a high saturation magnetization achievable at low applied magnetic fields. In-field Mössbauer spectra and ZFC/FC magnetization curves reveal a perfect ferrimagnetic ordering within nanoparticles with negligible spin frustration and interparticle interactions due to the complete coating of maghemite surfaces by the nanocrystalline laponite matrix. Magnetic iron oxide nanoparticles embedded in laponite matrix exhibit strong T2 weighted MRI contrast. The maghemite/laponite composite particles have 200 nm hydrodynamic diameter and form very stable hydrosols and/or hydrogels depending on their concentration in water.

Synthesis of magnetic carboxymethyl chitosan-g-poly(acrylamide)/laponite RD nanocomposites with enhanced dye adsorption capacity

“…The absence of free magnetic nanoparticles can be arisen from the cation exchangeability of laponite RD that helps the nanoparticles to form on the surface and between plates of laponite RD. A similar observation has been reported by Tzitzios et al, where magnetic nanoparticles have been immobilized on laponite RD discs [25].…”

Ni0.5Zn0.5Fe2O4 nanoparticles dispersed in a SiO2 matrix synthesized by sol–gel processing

“…The FC magnetization continuously increases below T B , as found in ensembles of independent or very weakly interacting superparamagnetic particles [47]. It is known that when inter-particle interactions are present, they are evidenced by a change in the FC magnetization curve below the corresponding blocking temperature; as the strength of the interactions increases [53,54] the curve tends to be nearly constant. In the present case, exchange interactions are largely reduced due to the relatively large separation between the NiZn ferrite particles embedded in the silica matrix, as illustrated in the TEM micrograph of Fig.…”

A Simple and Scalable Method for the Preparation of Magnetite/Graphene Oxide Nanocomposites under Mild Conditions

“…NaNO 3 , KMnO 4 , the iron precursor salts, concentrated sulfuric acid, and 30 wt.% hydrogen peroxide solutions were purchased from Molar Chemicals Ltd., Hungary. NaCl, NaOH, and HCl solutions used for maintaining constant background salt concentrations and constant pHs were used in analytical purity (Reanal).…”

“…H 2 SO 4 was added. e suspension was stirred continuously with a magnetic stirrer, and 3 × 1 g of KMnO 4 was added in three portions hour by hour, upon which the thick slurry turned to green and became more viscous due to the swelling of the graphite structure and the formation of graphite bisulphate. It was then heated to 52 ± 3°C and kept at this temperature for 6 hours.…”

“…Functional magnetic nanocomposites have been the focus of recent research due to their envisioned applications in biomedical, pharmaceutical, environmental, or nanoelectronic fields [1][2][3][4][5]. e most efficient use of these systems inevitably requires the precise control over their chemical and nanostructure.…”