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Superparamagnetism
About: Superparamagnetism is a research topic. Over the lifetime, 10264 publications have been published within this topic receiving 296477 citations.
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TL;DR: Magnetite nanoparticles coated with (3-aminopropyl)triethoxysilane, NH2(CH2)3Si(OC2H5)3 were prepared by silanization reaction and characterized by X-ray diffractometry, transmission electron microscopy, atomic force microscopy and Fourier transform infrared spectroscopy and magnetization measurements as mentioned in this paper.
727 citations
TL;DR: In this article, the grain size dependence of various mineral (rock) magnetic parameters has been determined, using a series of essentially pure, fine-grained (single domain, SD) and ultrafine-gained (superparamagnetic, SP) magnetites.
Abstract: The grain size dependence of various mineral (rock) magnetic parameters has been determined, using a series of essentially pure, fine-grained (single domain, SD) and ultrafine-grained (superparamagnetic, SP) magnetites. The parameters measured include low-field susceptibility, frequency-dependent susceptibility, saturation remanence (SIRM), anhysteretic susceptibility (XARM), and coercivity of remanence ((B0)CR). The magnetites were produced in experiments designed to simulate possible pedogenic and biogenic pathways of magnetite formation. Their mean grain sizes range from 0.012 um to 0.06 um, and hence span the SP/SD boundary. Isothermal magnetic measurements were performed on two separate subsets of differing packing densities. The response of the magnetic parameters is modified by interaction effects, but they display continuous variation across the entire grain size range, confirming their value for rapid magnetic granulometry. Within the fine and ultrafine end of the magnetite grain size spectrum, susceptibility, frequency dependent susceptibility and XARM are notably responsive to grain size change. In terms of magnetic response (and also possibly of grain size, shape and absence of cation substitution), these synhtetic magnetites represent close analogues of those found in some soils and sediments.
721 citations
TL;DR: In this article, the synthesis and coating of superparamagnetic monodispersed iron oxide nanoparticles was carried out by chemical solution method and controlled co-precipitation technique was used to prevent undesirable critical oxidation of Fe.
716 citations
TL;DR: Heterodimers of CdS and FePt with sizes of approximately 7 nm exhibit both superparamagnetism and fluorescence, indicating that the discrete properties of the individual parts of the dimers are preserved.
Abstract: Sequential addition of sulfur and Cd(acac)2 into the colloid solution of FePt nanoparticles (∼2.5 nm) under a reductive environment generates heterodimers of CdS and FePt with sizes of ∼7 nm. The heterodimers exhibit both superparamagnetism and fluorescence, indicating that the discrete properties of the individual parts of the dimers are preserved. This simple methodology may lead to the production of large quantities of various heterostructures with tailored properties on the nanoscale.
695 citations
TL;DR: This work provides a promising approach for the design and synthesis of multifunctional LDH microspheres, which can be used for the practical purification of recombinant proteins, as well as having other potential applications in a variety of biomedical fields including drug delivery and biosensors.
Abstract: Three-component microspheres containing an SiO2-coated Fe3O4 magnetite core and a layered double hydroxide (LDH) nanoplatelet shell have been synthesized via an in situ growth method. The resulting Fe3O4@SiO2@NiAl-LDH microspheres display three-dimensional core–shell architecture with flowerlike morphology, large surface area (83 m2/g), and uniform mesochannels (4.3 nm). The Ni2+ cations in the NiAl-LDH shell provide docking sites for histidine and the materials exhibit excellent performance in the separation of a histidine (His)-tagged green fluorescent protein, with a binding capacity as high as 239 μg/mg. The microspheres show highly selective adsorption of the His-tagged protein from Escherichia coli lysate, demonstrating their practical applicability. Moreover, the microspheres possess superparamagnetism and high saturation magnetization (36.8 emu/g), which allows them to be easily separated from solution by means of an external magnetic field and subsequently reused. The high stability and selectivi...
694 citations