Ofloxacin Removal from Aqueous Media by Means of Magnetoactive Electrospun Fibrous Adsorbents.

Functionalized electrospun polymer microfibrous membranes were fabricated by electrospinning and further surface-functionalized with magnetic iron oxide (FexOy) nanoparticles to yield magnetoactive nanocomposite fibrous adsorbents. The latter were characterized in respect to their morphology, mechanical properties and magnetic properties while they were further evaluated as substrates for removing Ofloxacin (OFL) from synthetic aqueous media and secondary urban wastewater (UWW) under varying physicochemical parameters, including the concentration of the pharmaceutical pollutant, the solution pH and the membranes' magnetic content. The magnetic-functionalized fibrous adsorbents demonstrated significantly enhanced adsorption efficacy in comparison to their non-functionalized fibrous analogues while their magnetic properties enabled their magnetic recovery and regeneration.

Fabrication, characterization, and evaluation in drug release properties of magnetoactive poly(ethylene oxide)-poly(L-lactide) electrospun membranes.

The fabrication of electrospun magnetoactive fibrous nanocomposite membranes based on the water-soluble and biocompatible poly(ethylene oxide) (PEO), the biocompatible and biodegradable poly(L-lactide) (PLLA) and preformed oleic acid-coated magnetite nanoparticles (OA.Fe3O4) is reported. Visualization of the membranes by electron microscopy techniques reveals the presence of continuous fibers of approximately 2 µm in diameter, with the magnetic nanoparticles being evenly distributed within the fibers, retaining at the same time their nanosized diameters (≈ 5 nm). Thermal gravimetric analysis measurements suggest that the magnetic nanoparticles embedded within the polymer fibers affect favorably the thermal stability of the membranes. Moreover, assessment of their magnetic characteristics by vibrating sample magnetometry discloses tunable superparamagnetic behavior at ambient temperature. For the first time, the biocompatibility and biodegradability of PEO/PLLA and the tunable magnetic activity of the OA.Fe3O4 are combined in the same drug delivery system, with N-acetyl-p-aminophenol (acetaminophen) as a proof-of-concept pharmaceutical. Furthermore, their heating ability under alternating current (AC) magnetic field conditions is evaluated using frequency of 110 kHz and corresponding magnetic field strength of 25 mT (19.9 kA/m). Consequently, these magnetoactive fibrous nanocomposites exhibit promising characteristics for future exploitation in magnetothermally triggered drug delivery.

Multiresponsive polymer conetworks capable of responding to changes in pH, temperature, and magnetic field: synthesis, characterization, and evaluation of their ability for controlled uptake and release of solutes.

This study deals with the preparation of novel multiresponsive (magnetoresponsive, thermoresponsive and pH-responsive) nanocomposite conetworks consisting of oleic acid-coated magnetite nanoparticles (OA·Fe(3)O(4)), hydrophilic/thermoresponsive hexa(ethylene glycol) methyl ether methacrylate (HEGMA), hydrophobic/metal binding 2-(acetoacetoxy)ethyl methacrylate (AEMA), and pH-responsive/thermoresponsive N-diethylaminoethyl methacrylate (DEAEMA) and 2-(dimethylamino)ethyl methacrylate (DMAEMA) moieties. Conventional free radical copolymerization was employed for the synthesis of random conetworks in the absence and presence of preformed OA·Fe(3)O(4). Further, in characterization of these materials in regards to their swelling behavior in organic and aqueous solvents, thermal/thermoresponsive properties, and composition, assessment of their magnetic characteristics disclosed tunable superparamagnetic behavior. These systems were also evaluated toward their ability to adsorb and release a solute (benzoic acid) in a controlled manner upon varying the pH.

The influence of particle clustering on the rheological properties of highly concentrated magnetic nanofluids.

In this paper the particle volume fraction and temperature dependence of the dynamic viscosity of highly concentrated transformer oil based magnetic nanofluids was investigated in the absence of an external magnetic field. The solid particle volume fraction dependence of the relative viscosity was found to be very well fitted by the Krieger-Dougherty formula, whence the mean ellipticity of the colloidal particles and the effective surfactant layer thickness were obtained. Using the information on the particles' size and shape statistics obtained from TEM, DLS and magnetogranulometry investigations, it was concluded that the magnetite nanoparticles agglomerate in small clusters of about 1.3 particles/cluster, due to the van der Waals interactions. The effective thickness of the oleic acid surfactant layer was estimated as about 1.4 nm, in very good agreement with the value resulted from previous SANS investigations.

Structure and in vitro biological testing of water-based ferrofluids stabilized by monocarboxylic acids.

Water-based ferrofluids (magnetic fluids) with double-layer steric stabilization by short monocarboxylic acids (lauric and myristic acids) are considered to be a potential source of magnetic nanoparticles in brain cancer (glioblastoma) treatment. Structure characterization in the absence of an external magnetic field is performed, including transmission electron microscopy, magnetization analysis, and small-angle neutron scattering with contrast variation. It is shown that despite the good stability of the systems a significant part of the magnetite nanoparticles are in aggregates, whose inner structure depends on the stabilizer used. In particular, an incomplete coating of magnetite particles is concluded in the case of myristic acid stabilization. The ferrofluids keep their structure unchanged when added to the cancer cell medium. The intracellular accumulations of magnetite from the ferrofluids added to cancer cell cultures as well as its cytotoxicity with respect to human brain cells are investigated.