An eco-friendly route to magnetic silica microspheres and nanospheres

Metabolic fate and subchronic biological effects of core-shell structured Fe3O4@SiO2-NH2 nanoparticles

Core-shell structured Fe₃O₄@SiO₂-NH₂ nanoparticles (Fe@Si-NPs) demonstrated outstanding potentials in drug targeting and delivery and medical imaging. However, they have limited clinical applications due to unknown chronic bio-effects and potential bio-related risks. In this study, the subchronic biological effects and metabolic fate of 20 nm Fe@Si-NPs in Sprague-Dawley rats in 12 weeks were investigated by the biochemical assay and NMR-based metabonomic analysis using an intravenous model. Biofluids (plasma and urine) analysis provided the transportation, absorption, and excretion information of Fe@Si-NPs. Urine metabonome displayed a metabolic recovery while self-regulation of plasma metabonome leaded to the parallel metabolic trends between dosed and control groups in 12 weeks. And biological tissues (spleen, liver, kidney, and lung) analysis indicated liver and spleen are the targeted-organs of Fe@Si-NPs. The obvious metabolic variations responding to the biodistribution were induced by Fe@Si-NPs although no visible toxic effects were observed in these tissues. Besides the common energy metabolism response to the xenobiotics, Fe@Si-NPs also disturbed the metabolic pathways in glycerophospholipid and sphingolipid metabolism, metabolisms of purine, pyrimidine, and nicotinate. Our results provide preliminary validation for the potential use of Fe@Si-NPs in clinical medicine and give identifiable ground for the dose selection and bio-nanoagent optimization.

Mechanistic investigation of the influence of phosphoric and boric acids in the formation of homogeneous Ni-P/ZnO@SiO2 coatings

High agglomeration of the nanoparticles and low volume fraction of nanosized inert particles within the nanocomposite thin films are found as the practical problems. In our previous work, silica coated ZnO nanoparticles (ZnO@SiO2 NPs) were synthesized to prevent dissolution of the ZnO nanoparticles (ZnO NPs) in the electrolytic Ni bath. The high agglomeration of these core-shell particles led to an unequal particle distribution in the deposit matrix. In this work, we aimed to prepare a highly homogeneous nanocomposite coating by stabilizing the nanoparticles in the medium. Adding the buffering agents, including phosphoric and boric acids to the medium, disclosed their new aspect of these inorganic acids in the prevention of particle agglomeration. The corrosion study of the resulting well-dispersed Ni-P/Zn@SiO2 nanocomposite coating confirmed a significant increase in anticorrosion performance. This increase was about 2.3 times compared to the previously prepared coating. Moreover, the probable mechanisms of phosphoric and boric acids in particle stability through the steric or/and electrostatic repulsion at the interfaces between the colloidal nanoparticles (ZnO@SiO2 NPs) and the electrolyte solution were investigated in detail.

Synthesis, characterization and application of core–shell magnetic molecularly imprinted polymers for selective recognition of clozapine from human serum

In this article, a magnetic molecularly imprinted polymer (MMIPs) based on Fe₃O₄@SiO₂ has been synthesized for simply extraction of clozapine (CLZ) from human serum.

Preparation of highly anisotropic cobalt ferrite/silica microellipsoids using an external magnetic field

Magnetic cobalt ferrite/silica microparticles having both an original morphology and an anisotropic nanostructure are synthesized through the use of an external magnetic field and nanoparticles characterized by a high magnetic anisotropy. The association of these two factors implies that the ESE (emulsion and solvent evaporation) sol-gel method employed here allows the preparation of silica microellipsoids containing magnetic nanoparticles aggregated in large chains. It is clearly shown that without this combination, microspheres characterized by an isotropic distribution of the magnetic nanoparticles are obtained. While the chaining of the cobalt ferrite nanoparticles inside the silica matrix is related to the increase of their magnetic dipolar interactions, the ellipsoidal shape of the microparticles may be explained by the elongation of the sol droplets in the direction of the external magnetic field during the synthesis. Because of their highly anisotropic structure, these microparticles exhibit permanent magnetic moments, which are responsible, at a larger scale, for the existence of strong magnetic dipolar interactions. Therefore, when they are dispersed in water, the microellipsoids self-assemble into large and irregular chains. These interactions can be reinforced by the use of external magnetic field, allowing the preparation of very large permanent chains. This research illustrates how nanostructured particles exhibiting complex architectures can be elaborated through simple, fast, and low-cost methods, such as the use of external fields in combination with soft chemistry.

Adsorption of lanthanum (III) from aqueous solution using 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester-grafted magnetic silica nanocomposites

In view of increasing attention of magnetic materials in the field of separation science and technology, we provide an effective route for fabrication of a new magnetic material with high adsorption capacity and selectivity toward metal ions, excellent acid resistance property and long service life. Silica was firstly coated on the magnetic particles, and then silane-coupling agent (3-chloropropyltryethosysilane) was used for grating 2-ethylhexyl phosphonic acid mono-2-ethylhexyl (P507), an organophosphorous acid extractant, on the surface of magnetic silica nanocomposite. The amount of P507 anchored on the particle was estimated to be 0.43 mmol/g. The P507-grafted magnetic silica nanocomposite was stable over pH range of 0-14. The maximum adsorption capacity of La (III) was 55.9 mg/g at the optimized pH 5.5. The adsorption of La (III) on our nanocomposites was found to follow the second order kinetics equation and fit Langmuir isotherm model well. The PO functional groups took an important role in the coordination and adsorption mechanism, which was confirmed by FTIR and XPS techniques. After 10 adsorption/desorption cycles, no obvious decrease in adsorption capacity or obvious loss in saturation magnetization were observed.