Vlad Socoliuc

Magnetic iron oxide nanoparticles: Recent trends in design and synthesis of magnetoresponsive nanosystems.

Recent developments in nanotechnology and application of magnetic nanoparticles, in particular in magnetic iron oxide nanosystems, offer exciting possibilities for nanomedicine. Facile and precise synthesis procedures, high magnetic response, tunable morphologies and multiple bio-functionalities of single- and multi-core magnetic particles designed for nanomedicine applications are thoroughly appraised. This review focuses on the structural and magnetic characterization of the cores, the synthesis of single- and multicore iron oxide NPs, especially the design of the latter, as well as their protection, stabilization and functionalization by desired coating in order to protect against the corrosion of core, to prevent non-specific protein adsorption and particle aggregation in biological media, and to provide binding sites for targeting and therapeutic agents.

Magnetically induced phase condensation in an aqueous dispersion of magnetic nanogels

The applicability of aqueous magnetic colloids depends on their colloidal stability under the influence of various factors like external magnetic field and temperature. The magnetically induced phase condensation of magnetic colloids leads to the formation of spindle-like condensed phase drops of highly packed magnetic colloidal particles. The condensed phase drops are aligned parallel to the external magnetic field and may grow up to several microns thickness and tens or even hundreds of microns length. Thus, the magnetically induced phase condensation could be an advantage in magnetic separation applications, whereas in magnetic drug targeting applications it could lead to blood vessel clogging as well as to a significant decrease of the specific surface. We present the results of an experimental study regarding the influence of the external magnetic field and temperature on the magnetically induced phase condensation in an aqueous dispersion of pNIPA magnetic nanogels. A theoretical model was developed for the analysis of the data from forward light scattering experiments. It was found that the volume weight of the condensed phase increases with passing time, with increasing field intensity and temperature decrease. Using the proposed model, the magnetic field intensity dependence of the initial supersaturation of the sample was calculated.

Synthesis of Magnetic Nanoparticles and Magnetic Fluids for Biomedical Applications

Chemical coprecipitation and gas-phase laser pyrolysis procedures were applied to obtain various iron-based magnetic nanoparticles (magnetite, maghemite, and carbon layer-coated iron) in the size range of 3–15 nm used as basic building blocks for functionalized core-shell particles, magnetic nanofluids, as well as multifunctional hybrid nanostructures based on stimuli-responsive biocompatible polymers and block copolymers. The particle size distribution, magnetostatic properties, surface coating efficiency, and embedding/encapsulation mechanisms of magnetic nanoparticles and particle clusters in various biocompatible polymer matrices (core-shell nanostructures, microgels, and micelles) were examined by TEM/HRTEM, vibrational sample magnetometry, dynamic light scattering, Fourier transform infrared spectroscopy, and small-angle neutron scattering. The novel magnetic hybrid nanostructured materials envisaged for MRI contrast agents, magnetic carriers in bioseparation equipment, or magnetothermally triggered drug delivery systems have superparamagnetic behavior and exhibit magneto- and thermoresponsive properties, high stability, and in vitro biocompatibility.

Clustering in Water Based Magnetic Nanofluids: Investigations by Light Scattering Methods

Nanosized magnetite particles, with mean physical diameter of about 7 nm, obtained by chemical coprecipitation procedure were dispersed in water carrier by applying sterical stabilization of particles in order to prevent their aggregation and to ensure colloidal stability of the systems. Different chain length (C12, C14, C18) carboxylic acids (lauric (LA), myristic (MA) and oleic (OA)) were used for double layer coating of magnetite nanoparticles. Structural and magnetic properties were investigated by electron microscopy (TEM), dynamical and static light scattering (DLS, SLS) and magnetometry (VSM) to evaluate the role of chain length and of the saturated/unsaturated nature of surfactant layers. Also investigated were two water based magnetic nanocomposites obtained by encapsulating the magnetic nanoparticles in polymers with different functional properties.

Chapter 4:Iron-oxide Nanoparticle-based Contrast Agents

This chapter discusses the synthesis, functionalization, characterization, and imaging applications of iron-oxide-nanoparticle-based contrast agents. By reducing the size from bulk to the nanometer scale (<20 nm), ferrimagnetic iron oxide acquires a magnetic property called superparamagnetism, which is key to the potential of these particles as MRI contrast agents. This chapter describes the theory governing the relaxivity of nanoparticle-based contrast agents. The different syntheses, coatings, and functionalization approaches are then discussed, including how these syntheses affect the properties of the nanomaterial. Different techniques for the characterization of the cores and coatings of nanoparticles, including their size and composition, are then discussed. Particular attention is given to characterization of the magnetic properties of iron oxide nanoparticles. Finally, the acquisition of MRI phantoms is presented.

Superparamagnetic Composites Based on Ionic Resin Beads/CaCO3/Magnetite

The preparation of superparamagnetic composites obtained by CaCO3 mineralization from supersaturate aqueous solutions is presented. The preparation was conducted in the presence of oleic acid stabilized magnetite nanoparticles as a water-based magnetic fluid and insoluble templates as gel-like cross-linked polymeric beads. The presence of the magnetic particles in the composites provides a facile way for external manipulation using a permanent magnet, thus allowing the separation and extraction of magnetically modified materials. Two ion exchangers based on divinylbenzene/ethyl acrylate/acrylonitrile cross-linked copolymer-a cation ion exchanger (CIE) and an amphoteric ion exchanger (AIE)-were used, as well as different addition orders of magnetite and CaCO3 crystals growth precursors. The morphology of the composites was investigated by SEM, the polymorphs content by X-ray diffraction, and the thermal stability by thermogravimetric analysis. Polymer, CaCO3 , and magnetite in the composite particles were shown to be present by energy dispersive X-ray (EDX), XPS, and TEM. The sorption capacity for CuII ions was tested, as compared to samples prepared without magnetite.