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In this work, we describe the preparation and characterization of highly magnetizable chloromethylated polystyrene-based nanocomposite beads. For synthesis optimization, acid-resistant core-shelled maghemite (γ-Fe 2 O 3 ) nanoparticles are coated with sodium oleate and directly incorporated into the organic medium during a suspension polymerization process. A crosslinking agent, ethylene glycol dimethacrylate, is used for copolymerization with 4-vinylbenzyl chloride to increase the resistance of the microbeads against leaching. X-ray diffraction, inductively coupled plasma atomic emission spectroscopy, thermogravimetric analysis, scanning electron microscopy, transmission electron microscopy, and optical microscopy are used for bead characterization. The beads form a magnetic composite consisting of ∼500 nm-sized crosslinked polymeric microspheres, embedding ∼8 nm γ-Fe 2 O 3 nanoparticles. This nanocomposite shows large room temperature magnetization (∼24 emu/g) due to the high content of maghemite (∼45 wt %) and resistance against leaching even in acidic media. Moreover, the presence of superficial chloromethyl groups is probed by Fourier transform infrared and X-ray photoelectron spectroscopy. The nanocomposite beads displaying chloromethyl groups can be used to selectively remove aminated compounds that are adsorbed on the beads, as is shown here for the molecular separation of 4-aminobenzoic acid from a mixture with benzoic acid. The high magnetization of the composite beads makes them suitable for in situ molecular separations in environmental and biological applications., Competing Interests: The authors declare no competing financial interest.

Remotely assisted drug delivery by means of magnetic biopolymeric nanoplatforms has been utilized as an important tool to improve the delivery/release of hydrophobic drugs and to address their low cargo capacity. In this work, MnFe 2 O 4 magnetic nanoparticles (MNPs) were synthesized by thermal decomposition, coated with citrate and then functionalized with the layer-by-layer (LbL) assembly of polyelectrolyte multilayers, with chitosan as polycation and sodium alginate as polyanion. Simultaneous conductimetric and potentiometric titrations were employed to optimize the LbL deposition and to enhance the loading capacity of nanoplatforms for curcumin, a hydrophobic drug used in cancer treatment. ~200 nm sized biopolymer platforms with ~12 nm homogeneously embedded MNPs were obtained and characterized by means of XRD, HRTEM, DLS, TGA, FTIR, XPS and fluorescence spectroscopy techniques to access structural, morphological and surface properties, to probe biopolymer functionalization and to quantify drug-loading. Charge reversals (±30 mV) after each deposition confirmed polyelectrolyte adsorption and a stable LbL assembly. Magnetic interparticle interaction was reduced in the biopolymeric structure, hinting at an optimized performance in magnetic hyperthermia for magneto-assisted drug release applications. Curcumin was encapsulated, resulting in an enhanced payload (~100 μg/mg). Nanocytotoxicity assays showed that the biopolymer capping enhanced the biocompatibility of nanoplatforms, maintaining entrapped curcumin. Our results indicate the potential of synthesized nanoplatforms as an alternative way of remotely delivering/releasing curcumin for medical purposes, upon application of an alternating magnetic field, demonstrating improved efficiency and reduced toxicity., (Copyright © 2018 Elsevier B.V. All rights reserved.)

The effect of Fe ion concentration on the morphological, structural, and optical properties of TiO2 films supported on silica (SiO2) opals has been studied. TiO2:Fe2O3 films were prepared by the sol-gel method in combination with a vertical dip coating procedure; precursor solutions of Ti and Fe were deposited on a monolayer of SiO2 opals previously deposited on a glass substrate by the same procedure. After the dip coating process has been carried out, the samples were thermally treated to obtain the TiO2:Fe2O3/SiO2 composites at the Fe ion concentrations of 1, 3, and 5 wt%. Scanning electron microscopy (SEM) micrographs show the formation of colloidal silica microspheres of about 50 nm diameter autoensembled in a hexagonal close-packed fashion. Although the X-ray diffractograms show no significant effect of Fe ion concentration on the crystal structure of TiO2, the μ-Raman and reflectance spectra do show that the intensity of a phonon vibration mode and the energy bandgap of TiO2 decrease as the Fe(+3) ion concentration increases.