Hydrophobically Coated Superparamagnetic Iron Oxides Nanoparticles Incorporated into Polymer-Based Nanocapsules Dispersed in Water

Abstract

This paper reports the characterization of iron oxide magnetic nanoparticles obtained via the thermal decomposition of an organometallic precursor, which were then loaded into nanocapsules prepared via the emulsification process in the presence of an amphiphilic derivative of chitosan. The applied synthetic method led to the formation of a hydrophobic layer on the surface of nanoparticles that enabled their loading in the hydrophobic liquid inside of the polymer-based capsules. The average diameter of nanoparticles was determined to be equal to 15 nm, and they were thoroughly characterized using X-ray diffraction (XRD), magnetometry, and Mössbauer spectroscopy. A core-shell structure consisting of a wüstite core and maghemite-like shell was revealed, resulting in an exchange bias effect and a considerable magnetocrystalline anisotropy at low temperatures and a superparamagnetic behavior at room temperature. Importantly, superparamagnetic behavior was observed for the aqueous dispersion of the nanocapsules loaded with the superparamagnetic nanoparticles, and the dispersion was shown to be very stable (at least 48 weeks). The results were analyzed and discussed with respect to the potential future applications of these nanoparticles and nanocapsules based on biopolymers as platforms designed for the magnetically navigated transport of encapsulated hydrophobic substances.

Polymer Capsules with Hydrophobic Liquid Cores as Functional Nanocarriers

“…A simple, one-step method of encapsulation of magnetic emulsion without any additional organic solvents or low-molecular-weight surfactants was shown by Gumieniczek-Chłopek et al [ 179 ]. The thermal decomposition method was applied to obtain magnetic nanoparticles consisting of wüstite cores of 6 nm in diameter and maghemite shells of 4.4 nm thickness.…”

Nanostructured Assembly of Magnetic and Plasmonic Nanoparticles Transferred from AOT Winsor Phases to Oil‐in‐Water Functional Dispersions

“…Further experiments would provide additional information about their biocompatibility in biological systems. Other encapsulating nanostructures of similar functionalities have been previously reported, namely the incorporation of nanoparticles in liposomes and microcapsules [41,42] . In contrast to these associates, our proposed nanostructures are also compartmentalized, incorporating layer‐by‐layer sub‐domains of different solvent affinities as well as the combination of more than two types of nanoparticle compositions, which is of interest for targeted delivery.…”

“…Other encapsulating nanostructures of similar functionalities have been previously reported, namely the incorporation of nanoparticles in liposomes and microcapsules. [41,42] In contrast to these associates, our proposed nanostructures are also compartmentalized, incorporating layerby-layer sub-domains of different solvent affinities as well as the combination of more than two types of nanoparticle compositions, which is of interest for targeted delivery. Note that the polyethyleneimine-stabilized nanoparticles, originally dispersed in water phase, were embedded in a matrix-shell of oleyl-capped nanoparticles and oleic acid, and the whole structure is again dispersed in a continuous water phase, resulting in oil-in-water dispersions.…”

Giant Vertical Magnetization Shift Caused by Field-Induced Ferromagnetic Spin Reconfiguration in Ni50Mn36Ga14 Alloy

“…There are two main types of exchange bias effect research, the horizontal exchange bias effect (EB) and the vertical magnetization shift (VMS). EB is the offset of the hysteresis loop along the field axis, which is observed and studied in many materials [5][6][7][8][9][10][11][12]; VMS is the offset of the hysteresis loop along the magnetization axis, which is only found in a small number of systems [13][14][15][16][17][18]. M E denotes the shift of the center of gravity of the hysteresis loop along the magnetization axis.…”