Fabrication of spherical Fe3O4 particles with a solvothermal method and their magnetorheological characteristics

Iron oxides based nanozyme sensor arrays for the detection of active substances in licorice

With the increasing applications of traditional Chinese medicines worldwide, authenticity identification and quality control are significant for them to go global. Licorice is a kind of medicinal material with various functions and wide applications. In this work, colorimetric sensor arrays based on iron oxide nanozymes were constructed to discriminate active indicators in licorice. Fe₂O₃, Fe₃O₄, and His-Fe₃O₄ nanoparticles were synthesized by a hydrothermal method, possessing excellent peroxidase-like activity that can catalyze the oxidation of 3,3',5,5' -tetramethylbenzidine (TMB) in the presence of H₂O₂ to produce a blue product. When licorice active substances were introduced in the reaction system, they showed competitive effect on peroxidase-mimicking activity of nanozymes, resulting in inhibitory effect on the oxidation of TMB. Based on this principle, four licorice active substances including glycyrrhizic acid, liquiritin, licochalcone A, and isolicoflavonol with the concentration ranging from 1 μM to 200 μM were successfully discriminated by the proposed sensor arrays. This work supplies a low cost, rapid and accurate method for multiplex discrimination of active substances to guarantee the authenticity and quality of licorice, which is also expected to be applied to distinguish other substances.

Controlled Synthesis of Polymethyl Methacrylate Latex Particles Armored by Fe3O4 via Pickering Emulsion Polymerization and Its Emulsifying Properties

The fabrication of polymethyl methacrylate (PMMA) latexes armored with modified Fe₃O₄ (IO) nanoparticles by Pickering emulsion polymerization was described. Dynamic light scattering analyzed the IO/PMMA latex particle size. Thermogravimetric analysis evaluated the incorporation efficiency (IE) of IO nanoparticles and the surface coverage (Cov) of latex particles. Scanning electron microscopy confirmed the IO nanoparticles loaded on the latex surface. Both the original and dialyzed IO nanoparticles were used as stabilizers to discuss the influence of electrolytes in IO solution on the process of emulsion polymerization. In order to effectively control the IE, Cov, hydrophobic properties, and magnetization of latex particles, the kinds of monomers, pH, and solid content of dialyzed IO on the polymerization process were investigated. In addition, the conversion of monomers, the size, and the number of latex particles were learned deeply so as to reveal the key mechanism of the PMMA polymerization process in the absence of electrolytes. Moreover, IO/PMMA latex particles showed good magnetic properties and emulsifying ability. In view of these results, a simple and efficient method for preparing magnetic hybrid materials by Pickering emulsion polymerization was proposed.

Fe3O4@C Nanoparticles Synthesized by In Situ Solid-Phase Method for Removal of Methylene Blue

Fe3O4@C nanoparticles were prepared by an in situ, solid-phase reaction, without any precursor, using FeSO4, FeS2, and PVP K30 as raw materials. The nanoparticles were utilized to decolorize high concentrations methylene blue (MB). The results indicated that the maximum adsorption capacity of the Fe3O4@C nanoparticles was 18.52 mg/g, and that the adsorption process was exothermic. Additionally, by employing H2O2 as the initiator of a Fenton-like reaction, the removal efficiency of 100 mg/L MB reached ~99% with Fe3O4@C nanoparticles, while that of MB was only ~34% using pure Fe3O4 nanoparticles. The mechanism of H2O2 activated on the Fe3O4@C nanoparticles and the possible degradation pathways of MB are discussed. The Fe3O4@C nanoparticles retained high catalytic activity after five usage cycles. This work describes a facile method for producing Fe3O4@C nanoparticles with excellent catalytic reactivity, and therefore, represents a promising approach for the industrial production of Fe3O4@C nanoparticles for the treatment of high concentrations of dyes in wastewater.

Magnetorheology: a review

Magnetic Soft Matter is a rapidly evolving discipline with fundamental and practical interest. This is due to the fact that its physical properties can be easily controlled through external magnetic fields. In this review paper, we revisit the most recent progress in the field (since 2010) emphasizing the rheological properties of these fascinating materials. New formulations and flow kinematics are discussed. Also, new members are integrated into the long-lived magnetorheology family and suggestions are provided for future development.

Fabrication of spherical CoFe2O4 nanoparticles via sol–gel and hydrothermal methods and investigation of their magnetorheological characteristics

CoFe₂O₄ nanoparticles are synthesized through sol–gel and facile hydrothermal methods, and their magnetorheological (MR) characteristics are evaluated.